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Melatonin
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In one pass Melatonin is not a sleeping pill that knocks you out. Not this — 5-10 mg melatonin helps you sleep — A physiological dose of 0.3 mg works as well; 5-10 mg overloads the receptors, bringing next-day grogginess and a disrupted body clock.
Educational content, not medical advice — consult a clinician.
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Chapter 1
How the body makes it at night
Melatonin is not a sleeping pill that knocks you out. It is a message: it is dark now, time to get ready for sleep. About two hours before your usual bedtime, a pea-sized gland deep in the brain, the pineal gland, starts releasing it into the blood.
How does it know it is dark? Through a small group of cells in the eye that do nothing but measure brightness: intrinsically photosensitive retinal ganglion cells (ipRGCs). They carry a light-sensitive pigment called melanopsin that responds most to blue light around 480 nm, and they report light and dark straight to the brain's master clock, the suprachiasmatic nucleus (). While there is light, the SCN holds melatonin down; once it is dark, the SCN lets go and melatonin climbs. Staring at a bright screen at night tells the SCN it is still daytime.
So taking melatonin mainly changes when you start to feel sleepy; its direct sleep-inducing effect is small. It suits situations where the body clock is out of step, such as jet lag. If you have young children, store it like a medicine, gummies above all: if a child who swallowed some is too drowsy to wake or is breathing abnormally, call emergency services now.
How does it know it is dark? Through a small group of cells in the eye that do nothing but measure brightness: intrinsically photosensitive retinal ganglion cells (ipRGCs). They carry a light-sensitive pigment called melanopsin that responds most to blue light around 480 nm, and they report light and dark straight to the brain's master clock, the suprachiasmatic nucleus (). While there is light, the SCN holds melatonin down; once it is dark, the SCN lets go and melatonin climbs. Staring at a bright screen at night tells the SCN it is still daytime.
So taking melatonin mainly changes when you start to feel sleepy; its direct sleep-inducing effect is small. It suits situations where the body clock is out of step, such as jet lag. If you have young children, store it like a medicine, gummies above all: if a child who swallowed some is too drowsy to wake or is breathing abnormally, call emergency services now.
Mechanism · How it weakens the wake drive
What it really does in sleepMelatonin does not put you to sleep directly. It is the signal that tells the body it is night. Sleep itself is driven by several forces together: the sleep pressure that builds the longer you stay awake (adenosine accumulating in the brain), plus the body clock reaching its hour. Melatonin does three things: it shifts the phase of the body clock (which is why it is also called a phase shifter), it helps core body temperature drift down a little, and it weakens the wake drive.
Weakens the wake drive is the phrase most easily skimmed past, yet the whole weight of the conclusion it is a phase shifter, not a sedative rests on it. Taken apart, it is three steps. First, a word on the level of evidence: most of the receptor roles below come from animal experiments and human pharmacology studies; they have not been directly observed in a living human brain.
Step 1 · Where it lands
Melatonin travels everywhere in the bloodstream, but it only acts where the matching socket is installed. That socket is the melatonin receptor, which comes in two main types, MT1 and MT2, both members of the G-protein-coupled receptor (GPCR) family. Think of a door handle on the outside of the cell membrane: once the molecule docks, a signaling chain inside the cell is set moving.
In the brain, these two receptors are densest in exactly two places that have to do with being awake:
The suprachiasmatic nucleus (), the master clock itself. In the daytime it fires at a high rate on its own, and that firing is one source of the stay awake commandThe preoptic area, at the front of the hypothalamus, which helps start sleep and also holds the body's temperature set point
Step 2 · What happens once it docks
When melatonin docks on MT1 on SCN neurons, an excitatory messenger inside the cell is turned down and the neurons' firing rate falls with it. The SCN's daytime stay awake command weakens as a result. Notice the direction: nobody pressed a sleep switch; the wake command itself got smaller. That is the literal meaning of weakens the wake drive, and it is the deepest line between melatonin and a sleeping pill: a sleeping pill adds force to the brake (it boosts inhibitory signals), while melatonin only eases off the accelerator a little. Easing off the accelerator does not stop the car at once, which is exactly why so many people complain that they "took it and felt nothing". What they were expecting was the brake.
The share that docks on MT2 is mainly in charge of moving the clock: it changes the phase of the rhythm cells inside the SCN, sliding the whole timetable earlier or later. The same tablet, taken at different times, can move the clock in opposite directions; the chapter on jet lag and shift work explains how.
Step 3 · Why body temperature drops with it
The small blood vessels in the skin of the hands and feet also carry melatonin receptors. When melatonin docks, those vessels relax and widen, blood flow to the hands and feet rises, and heat leaves through the skin of the limbs. This is precisely how the body's core cools, by giving heat away. Warm hands and feet when you are sleepy are no coincidence: that is the core temperature falling. At the same time the temperature set point in the preoptic area is nudged down a little, so the body actively helps the drop along.
A falling core temperature is itself one of the conditions for falling asleep: while temperature is on its downslope, the threshold for sleep is at its lowest. So some researchers think a large part of the helps you fall asleep feeling from melatonin runs through temperature, rather than acting directly on consciousness.
These three steps explain three things you would otherwise have to memorize
Why it is most useful for jet lag: jet lag is at heart a phase mismatch, and the MT2 route is exactly the one that shifts phaseWhy ordinary immediate-release melatonin does little for waking again and again in the night: that is not a phase problem, and moving the clock cannot reach itWhy cooling the bedroom also helps you fall asleep: it lands at the same endpoint as melatonin, sending core temperature down. One takes heat away from outside; the other lets the body release heat from inside
Numbers · The daily melatonin curve and age
The typical rhythm across a dayDaytime plasma level < 10 pg/mLThe rise starts around 9–10 pm. That starting point is called dim light melatonin onset (DLMO): the moment melatonin secretion is first detected under dim lightThe peak comes between 2–4 am. How high it runs varies widely between people (roughly tens to a little over a hundred picograms per milliliter; higher in children, markedly lower in older people)Back to baseline by 6–7 am
How to read this curve
What matters is not the absolute value at any one moment but when the rise happens. The DLMO turning point is the starting gun for the whole body's timetable: move it a few hours later and everything hanging downstream of it (when core temperature starts to fall, when deep sleep appears, when next-day cortisol starts to rise) moves later with it. So not being able to get up after a late night is not only a matter of willpower: the starting gun itself went off late, and the body is simply following the new timetable.
And because what you read is the turning point, not the total, a low peak in old age does not automatically mean you should take it. Someone with a low peak but an on-time turning point has the right timetable; a young adult with a normal peak whose screens push it two hours later every night is the one whose timetable is off.
What age and modern life do to it
After 30 the peak falls with age, and in old age it is markedly lower than in the young. But the size of the drop differs too widely between published studies, so this page gives a direction, not a percentage. Evening screen light pushes the same way: in a controlled trial, reading a light-emitting e-reader for 4 hours a night on 5 consecutive nights suppressed evening melatonin by about 55% on the fifth night and delayed its onset (details on the page about screen light). By mechanism, everyday evening screen use is a weaker version of the same effect; how much blue-light glasses or a phone's night mode help in daily life is a question that trial did not answer.
A common misconception: more serotonin means better sleep is only half right. Serotonin is the raw material for melatonin, but supplementing serotonin or tryptophan on its own is generally thought not to raise melatonin output noticeably, because the pace of synthesis is set at other steps.
The route from raw material to melatonin is: tryptophan → 5-hydroxytryptophan () → serotonin () → N-acetylserotonin → melatonin. The rate-limiting enzyme on this line is aralkylamine N-acetyltransferase (AANAT), and it too takes orders from the body clock: the holds it down by day and releases it after dark, and only when its activity rises can melatonin climb.
Mechanism · How screen light delays melatonin
Screens disturb sleep not because of tired eyes but because light sends the body clock the wrong signal.The retina holds a small group of special ganglion cells that contain melanopsin, called intrinsically photosensitive retinal ganglion cells (ipRGCs). They make up only 1–2% of these cells and respond most to blue light at 460–480 nm. They do not help form images; instead they send brightness information straight to the and a few other brain areas that handle rhythm and pupil size. That is the route by which light sets the body clock.
The blue-light signature of modern screens:
Phone and tablet displays: a blue peak around 450 nm, close to the band melanopsin is most sensitive toCool-white office LED lighting is similarLooking at a screen at night, the SCN receives an it is still daytime signal, holds AANAT down, and the melatonin rise is delayed
Chang 2015 (PNAS) is the most-cited controlled trial on this: 12 healthy young adults lived in a laboratory in a randomized crossover design. In one round they read on a light-emitting e-reader in a very dim room, in the other they read printed books, for about 4 hours a night on 5 consecutive nights. In the e-reader round, evening melatonin on the fifth night was suppressed by about 55%, melatonin onset came more than 1.5 hours later than in the print round, falling asleep took longer, and the next morning they were less alert.
Know its limits: this was in an almost dark room, for 4 hours a night, 5 nights running. With the lights on and half an hour of scrolling, the mechanism predicts a smaller effect; how much smaller, the trial did not measure.
What you can do (all inferred from this mechanism; none has been compared on its own in a large trial):
1. Put screens down 1–2 hours before bed
2. Turn on a screen's night mode (Night Shift, f.lux and the like) to cut some of the blue light
3. Blue-blocking glasses (orange-tinted lenses): they have to actually block light around 480 nm; a slight yellow tint does nothing
4. In the evening, use warm indoor light (2700–3000 K) instead of cool white
5. Get 10 minutes of bright light after you get up in the morning. It is the opposite of the evening case and helps the SCN anchor daytime
Dimming a screen cuts the total amount of light; warming its color cuts the band of blue light the eye is most sensitive to. Both push in the same direction.
Children and screens: children are generally thought to be more sensitive to evening light. The American Academy of Pediatrics (AAP) advises that very young children avoid screens apart from video chat, and that school-age children stop using screens for a while before bed. Short sleep in children and teenagers is consistently associated with using phones and tablets at bedtime (Carter 2016, a in JAMA Pediatrics). But all 20 studies it pooled were cross-sectional surveys: they can show that the two travel together, not which causes which. It is also possible that children who already sleep badly are more likely to pick up a screen at night. The Chang trial above is the evidence for the causal direction, and what it measured was melatonin under laboratory conditions, not insomnia rates in the population.
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Chapter 2
Why small doses are enough
Melatonin is the clearest counter-example to a bigger dose works better. Taking 0.1 mg by mouth is already enough to raise blood melatonin into the normal nighttime range (Dollins 1994: 20 healthy men, dosed at noon); the 3–10 mg products common on the shelf are tens of times to a hundred times that amount.
The extra dose does not buy better sleep. In a crossover trial in people over 50 (Zhdanova 2001), those whose sleep efficiency had fallen recovered on 0.3 mg; 3.0 mg also improved sleep but lowered body temperature and left melatonin in the blood until after daybreak; and people who already slept well did not change on any dose.
So if you take it, start at the lowest step. If a few weeks of trying still does nothing, stop and look for the cause instead of raising the dose.
The extra dose does not buy better sleep. In a crossover trial in people over 50 (Zhdanova 2001), those whose sleep efficiency had fallen recovered on 0.3 mg; 3.0 mg also improved sleep but lowered body temperature and left melatonin in the blood until after daybreak; and people who already slept well did not change on any dose.
So if you take it, start at the lowest step. If a few weeks of trying still does nothing, stop and look for the cause instead of raising the dose.
Numbers · How many milligrams is enough
The physiological peak comes between 2–4 am, but how high it runs varies widely between people, so using it as the denominator for how many times too much is unreliable. There is a firmer ruler: 0.1 mg by mouth is already enough to raise plasma melatonin into the normal nighttime range. Dollins 1994 (PNAS) gave 20 healthy men 0.1, 0.3, 1.0 or 10 mg at noon: from 0.1 mg upward, daytime blood melatonin entered the nighttime range and they fell asleep faster; the larger doses brought no extra benefit. Divide the shelf doses by 0.1 mg and the mismatch is plain.0.1–0.5 mg: Zhdanova 2001 (JCEM) ran a randomized, double-blind, placebo-controlled crossover trial in people over 50: 15 whose reduced sleep efficiency was confirmed by wrist activity monitoring, plus 15 normal sleepers as controls. Each took placebo and 0.1 / 0.3 / 3.0 mg in turn, a week each. 0.3 mg restored sleep efficiency in the poor-sleeping group; in the normal sleepers, no dose changed their sleep. That second half is the most direct evidence that people who already sleep well get nothing from it3 mg: roughly 30 times the dose needed to bring plasma back into the nighttime range. In the same trial, 3.0 mg also improved sleep but caused a drop in body temperature below normal and kept blood melatonin high into the daytime5–10 mg: roughly 50–100 times. In the jet-lag studies, doses above 5 mg were no better (the Cochrane review). Next-day grogginess and headache are commonly mentioned side effects, but there are no reliable figures here for how often they occur at each dose
Why are most shelf products 3–10 mg? The usual explanations are below; none has been checked directly by research:
1. Early products in the 1990s were dosed by the habits of ordinary tablets, not by the dose studies that came later
2. Consumers assume a bit more is safer
3. Melatonin is a natural molecule, so makers set themselves apart mainly by dose and packaging
4. Stronger action marketing, which the dose studies above do not support
Why a large dose may actually be worse:
Too high a blood level leaves some behind the next day, showing up as grogginess and headache, the so-called melatonin hangover. What Zhdanova 2001 saw in the 3.0 mg arm was exactly this: blood levels dragging on into the daytime. By contrast, the earlier Zhdanova 1995 gave healthy volunteers 0.3 or 1.0 mg in the evening and found no hangover effect on mood and performance tests the next morningReceptors bathed in high melatonin for a long time become less sensitive; this is seen in cell and animal experiments. Whether people on large doses for a long time become tolerant because of it has not been measured directlyMelatonin is linked to the reproductive hormone axis of (LH) and (FSH), mostly on animal evidence, so some worry that large doses could affect puberty or menstruation. Human data are scarce; this is a concern, not a proven harmThere are also reports of vivid dreams and brief mood swings
How to pick a dose:
Jet lag: in the Cochrane review 0.5–5 mg worked about equally well, with people falling asleep a little faster on 5 mg; take it close to bedtime at the destinationOlder and struggling to fall asleep: you can start from the 0.3 mg step (the Zhdanova 2001 population was over 50)Children: only under a doctor's guidance, with the dose set by the doctor, and not as an everyday supplementSpecial cases (blind people, severe circadian rhythm disorders): prescription doses with medical supervision, possibly higher
A cautious 4-week trial (laid out from the dose ladder above; not a protocol tested in a trial):
1. 0.3 mg taken 30 minutes before bed, for 1 week
2. No effect: raise to 0.5 mg, for another week
3. Still no effect: raise to 1 mg, for another week
4. If 1 mg still does nothing, the problem is not the dose; it lies outside what melatonin can reach. See a doctor instead of going higher
zhdanova-1995-csaspt
Evidence · What the dose trials and reviews say
Put the key studies side by side and the picture is clear.Zhdanova 2001 (JCEM), a dose trial for age-related insomnia: people over 50, a randomized, double-blind, placebo-controlled crossover design, N=30, of whom 15 had reduced sleep efficiency confirmed by wrist activity monitoring and 15 slept normally as controls. Each took placebo and 0.1 / 0.3 / 3.0 mg in turn, 30 minutes before bed, a week each. 0.3 mg restored sleep efficiency in the poor-sleeping group and brought their nighttime blood melatonin back to normal. 0.1 mg and 3.0 mg also improved sleep, but 3.0 mg caused a drop in body temperature below normal and kept blood melatonin high into the daytime. And in the 15 who already slept normally, no dose changed their sleep. Give that half the same weight as the first: it is the evidence for if you sleep well, do not take it inside the same paper. This was a small trial of 30 people; within it, 0.3 mg struck the best balance between effect and side effects, and it still needs to be repeated in a larger trial.
A by Brzezinski 2005 (Sleep Medicine Reviews) (17 studies, 284 people):
Time taken to fall asleep shortened by about 4 minutesTotal sleep time rose by about 12–13 minutesSleep efficiency improved by about 2–3%The effect is real but small. The studies differed widely in population, dose and route, and this pooled analysis did not compare melatonin with sleeping pills directly
The American Academy of Sleep Medicine (AASM) 2015 guideline (Auger 2015) covers disorders where the body's own rhythm goes wrong; jet lag and shift work are outside it. It recommends strategically timed melatonin in three situations, all at the second tier (a weak recommendation): delayed sleep-wake phase disorder, non-24-hour rhythm disorder in blind adults, and children and adolescents with an irregular sleep-wake pattern and a neurological disorder. For older people with dementia, it advises against melatonin. The guideline gives no general-purpose dose; the timing has to be set by the diagnosis and the person's own rhythm. Ordinary insomnia in adults is a different matter: the American College of Physicians (ACP) 2016 guideline makes cognitive behavioral therapy for insomnia () the first choice for chronic insomnia.
Herxheimer 2002, a Cochrane review (jet lag): of 10 randomized trials, 9 found that melatonin taken close to bedtime at the destination (about 10 pm to midnight) eased jet lag from flights crossing five or more time zones. The (NNT) was 2: for every 2 people who take it, one more benefits than with placebo. Doses between 0.5 and 5 mg worked about equally well, except that people fell asleep faster and slept better on 5 mg than on 0.5 mg; above 5 mg was no better; and a 2 mg slow-release form did relatively poorly, suggesting that a short, high peak works better. The review is stricter about timing than about dose: taken too early, in the daytime, it causes sleepiness and delays adaptation. The benefit is greater flying east and the more time zones are crossed. The reviewers concluded that it is remarkably effective for jet lag and that occasional short-term use appears to be safe.
Children:
Children and adolescents with a neurological disorder and irregular sleep: a weak recommendation from AASM 2015, to be used under a doctor's guidanceHealthy children with trouble falling asleep: start with routine and behavior, not with gummiesUS poison control centers received 260,435 reports of children ingesting melatonin between 2012 and 2021, and the yearly number rose 530%; the rise in hospital stays and serious outcomes came mainly from accidental ingestion by children aged 5 and under. In the same report, 5 children needed mechanical ventilation and 2 died (CDC 2022 MMWR). The report links this to rising sales and availability of melatonin over those years; candy-like gummies also make it easier for a child to eat many at once. If a child who swallowed some is too drowsy to wake or is breathing abnormally, call emergency services now; even without symptoms, call poison control or an emergency department for advice
Taken together:
A bigger dose works better is wrong: from 0.1 mg upward, blood levels already reach the nighttime range, and in the jet-lag studies doses above 5 mg were no betterOne tablet every night as insurance has no evidence behind it, and data on long-term effects are scarceFor jet lag and a few diagnosed rhythm disorders it helps, but only with the right dose at the right time
Chapter 3
Using it for jet lag and shift work
Melatonin's best-supported use is jet lag. It is a signal that moves the body clock, not a sleeping pill, so when you take it matters more than how much.
The randomized trials pooled in a Cochrane review show that on flights crossing five or more time zones, 0.5–5 mg taken after arrival close to local bedtime (about 10 pm to midnight) eases jet lag, and the benefit is greater flying east and the more time zones are crossed. The same review warns that taken too early, in the daytime, it makes you sleepy during the day and actually slows adaptation. Going outdoors into light on the mornings after arrival pushes in the same direction as the evening melatonin.
Starting to move the clock earlier a few days before you leave is a separate pre-adjustment plan (going to bed a little earlier each day and getting bright morning light), and it lies outside that review. In shift work it helps only a little, and ordinary insomnia is not its strength either.
The randomized trials pooled in a Cochrane review show that on flights crossing five or more time zones, 0.5–5 mg taken after arrival close to local bedtime (about 10 pm to midnight) eases jet lag, and the benefit is greater flying east and the more time zones are crossed. The same review warns that taken too early, in the daytime, it makes you sleepy during the day and actually slows adaptation. Going outdoors into light on the mornings after arrival pushes in the same direction as the evening melatonin.
Starting to move the clock earlier a few days before you leave is a separate pre-adjustment plan (going to bed a little earlier each day and getting bright morning light), and it lies outside that review. In shift work it helps only a little, and ordinary insomnia is not its strength either.
Clinical · Where jet lag, shifts and insomnia differ
Why taking it at the wrong time backfires, instead of just doing nothingFirst hold on to two directions: advancing the clock suits flying east (for example London → Beijing, where you need to sleep and wake earlier); delaying it suits flying west (for example Beijing → London, where you need to sleep and wake later). The Cochrane review found less benefit on westward flights, since pushing the clock later is easier to begin with.
Shifting phase has a direction. Lewy 1998 found that melatonin's phase response curve runs about 12 hours out of step with the one for light: a dose that lands on the evening side of your clock moves it earlier, and one that lands on the early-morning side moves it later. So taking it at the wrong hour is not a wasted tablet. You have pushed your own clock one notch in the direction you did not want. That is a failure a sleep aid simply cannot have, and it is the costliest practical consequence of melatonin is a phase shifter, not a sedative. By this curve, an early-morning dose can push the clock later, but that use lacks good trials, easily causes daytime sleepiness, and is not routine practice.
Herxheimer 2002, the Cochrane review: across five or more time zones, the (NNT) was 2, meaning that for every 2 people who take it, one more benefits than with placebo. People crossing 2–4 time zones can also use it if they need to.
Shift work
This is a complicated and punishing situation, and melatonin can help only so much:
Sleeping in the day after a night shift: a small dose on getting home in the morning (about 6–7 am), before going to sleep, is a common use. But the American Academy of Sleep Medicine's evidence review (Sack 2007) pooled studies using 0.5–10 mg and concluded that the evidence of benefit is mixed; even when the daytime sleep is somewhat better, that may come from its sleep-inducing effect rather than from actually moving the clock. Do not take it before driving or operating machineryNote that these are two different uses; do not mix them up. The dose above signals the that your night is starting. To move the whole clock earlier (changing shift direction, or delayed sleep-wake phase disorder), a small dose is taken well ahead, about 4–6 hours before the target sleep time, based on Lewy's phase response curve above. The exact hour is best set by a doctor from your own rhythmSwitching back to a day schedule at the weekend: the transition is messy; melatonin is only a helper, and managing light does most of the workFixed night shifts versus rotating night shifts: rotating ones are harder to adjust toIf you have a choice, aim for longer stretches on a fixed shift; the more often shifts change, the less the clock can keep up
Why shift work is much harder than jet lag
Jet lag only needs the clock moved once, as a whole; after that, the local sun holds it in place for you. Light and your new schedule agree, and the clock anchors itself. Shift work has no such help: you ask the body to sleep when it is light and wake when it is dark, while the sun outside pulls the other way every day. The strongest signal the SCN receives is always light; melatonin can only push quietly from the side.
So in shift work the real work is done by blocking light (making the bedroom into night while you sleep in the day) and timed bright light (using strong light before the shift to prop up the wake side). Melatonin only helps line up the start of that sleep. Rotating shifts are the hardest because they do not even have one stable target hour: each move of the clock takes several days to complete, and the roster changes faster than that.
Ordinary insomnia is not jet lag or shift work
The first choice for chronic insomnia is cognitive behavioral therapy for insomnia (). Many randomized trials support it, and guidelines from the American College of Physicians (ACP) and the American Academy of Sleep Medicine (AASM) both make it first-line; unlike sleeping pills, its effect lasts after treatment ends. Melatonin has a small effect on ordinary insomnia and is not a first choice. Broken down into three types:
Trouble falling asleep: this may be delayed sleep-wake phase disorder (DSPD), where the whole timetable runs late. AASM 2015 gives timed melatonin a weak recommendation for it, but it needs a diagnosis firstWaking too early: this may be the advanced type (ASPD), where the whole timetable runs early. For it, AASM 2015 recommends evening light, not melatoninWaking several times in the night: ordinary immediate-release melatonin does little; causes such as sleep apnea, anxiety and needing to urinate at night should be looked into
Why these three types get three different answers
Put them back onto the receptor mechanism and it is clear: all melatonin can do is slide the whole timetable earlier or later, plus press the wake drive down a little.
Trouble falling asleep (the whole timetable runs late) is exactly its shape: slide the timetable back and the problem is solvedWaking too early (the whole timetable runs early) needs a later shift. By the phase response curve an early-morning dose pushes later, but that use lacks trials, and the guideline's tool is evening lightWaking again and again at night is not a timetable problem at all: the timetable is on time, and something else is breaking up sleep in the night (the gasping awake of apnea, the jolt awake of anxiety, the bladder). Moving the timetable cannot remove something that knocks every night, so raising the dose does not help either
If it did not work, take more is a trap for exactly this reason: it assumes all insomnia is one illness and merely under-dosed, while the third type is not even within this tool's range.
So people who casually pop a melatonin tablet are mostly using it in the wrong place. Jet lag and a few specific rhythm disorders are its strengths; ordinary insomnia is its weakness.
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In practice · The six parts of CBT-I
Why do most doctors not reach for melatonin first? Because there is a stronger option: cognitive behavioral therapy for insomnia (). It has six parts.① Sleep restriction, the most counterintuitive part and considered the most powerful:
Cut the time spent in bed down to the time actually spent asleep, which raises sleep efficiencyExample: into bed at 11, asleep at 1, up at 6: 5 hours of sleep, but 7 hours in bedPrescription: time in bed = 5 hours, into bed at 1 am, up at 6 amKeep it up for 1–2 weeks: sleep pressure builds, you fall asleep faster, and efficiency risesThen extend it by 15 minutes a week until you find the length that suits you
② Stimulus control:
The bed is for sleep and sex only: no phone, work or TV in bedIf you are not asleep after 20 minutes, get up, go somewhere else, do something boring, and come back when sleepyThis rebuilds the conditioned link between bed and sleep
③ Sleep hygiene: a room at 18–20°C; a bedroom as dark and quiet as you can make it; the same time up and to bed every day, even after a bad night; caffeine stopped at least 6 hours before bed (in Drake 2013, 400 mg of caffeine taken 6 hours before bed still disrupted sleep; if you usually go to bed at 22–23, stop after 2 pm); less alcohol (it breaks up the second half of the night); screens put down 1–2 hours before bed.
④ Cognitive restructuring: the thought "I must get 8 hours tonight" is one of the strongest accelerants of insomnia. Rewriting it as "a bad night does not mean I cannot work tomorrow" breaks the vicious circle of worrying about sleep and sleeping worse for it.
⑤ Relaxation training: progressive muscle relaxation, mindfulness meditation, 4-7-8 breathing. The goal is not just relaxing before bed but reducing hyperarousal during the day.
⑥ Paradoxical intention (an advanced technique): deliberately trying to stay awake, which takes away the pressure of having to fall asleep.
Evidence: many randomized trials and the that pool them support CBT-I, and an evidence review (Morin 2006) shows its improvements hold at follow-up. Few trials compare it head to head with sleeping pills: in the short term they are roughly similar, and in the long term CBT-I holds up better. Guidelines from the American Academy of Sleep Medicine (AASM 2021) and the American College of Physicians (ACP 2016) both make it first-line treatment for chronic insomnia. The regulatory status of the digital versions differs and should not be flattened into approved: Somryst is a prescription digital therapeutic cleared by the US FDA (the commercial successor to the SHUTi program used in the research; SHUTi itself was never approved), Sleepio went the route of a UK NICE / NHS recommendation, and CBT-I Coach is a free app from the US Department of Veterans Affairs.
So treating chronic insomnia with melatonin before trying CBT-I means skipping the stronger option. The reasonable path is CBT-I first, with melatonin as a short-term helper if needed.
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Chapter 4
Labels often get the dose wrong
The milligrams printed on a melatonin bottle often do not match what is inside. In a Canadian sampling study, more than seven in ten products were more than 10% off their label, and the same product could differ several-fold from one batch to the next; in a US test of gummies, one product contained no melatonin at all.
The errors showed no link to brand or product type, so picking a brand cannot solve it. The root is regulation: in the United States it is sold as a dietary supplement, and its content does not need FDA review before it goes on sale.
One hard rule: people taking the antidepressant fluvoxamine should not combine the two, because fluvoxamine raises melatonin exposure in the blood about tenfold.
The errors showed no link to brand or product type, so picking a brand cannot solve it. The root is regulation: in the United States it is sold as a dietary supplement, and its content does not need FDA review before it goes on sale.
One hard rule: people taking the antidepressant fluvoxamine should not combine the two, because fluvoxamine raises melatonin exposure in the blood about tenfold.
Safety · Content, child ingestions, interactions
Erland 2017 (Journal of Clinical Sleep Medicine) tested 31 melatonin products sold in Canada (where they are registered as natural health products):Measured content versus label: -83% to +478%More than 71% of products fell outside ±10% of the labeled amountBetween batches of the same product, content differed by as much as 465%. Even if you always buy the same bottle, you cannot know whether this batch delivers the same amount as the lastThese errors showed no link to manufacturer or product typeEight products (about 26%) contained serotonin () that was not on the label, at 1 to 75 μg
Do not skip that μg: it decides how this risk should be read. 1–75 μg is a microgram-level amount, and a microgram is a thousandth of a milligram, which is very small; serotonin taken by mouth is poorly absorbed and does not cross the blood-brain barrier. So the paper's point is not that these products cause serotonin syndrome (an emergency caused by too much serotonin activity), but that an active molecule not listed on the label turned up in the bottle. For someone taking an antidepressant such as an or an , the real problem is not knowing what you swallowed, not this particular amount.
Children's gummies were measured by a different study: Cohen 2023 (JAMA) analyzed 25 melatonin gummy products sold in the US. One contained no melatonin at all, and the rest measured 74% to 347% of the labeled amount. A gummy labeled 1 mg may turn out to be 0.74 mg, or 3.5 mg.
Rules differ from place to place:
United States: a dietary supplement, with no FDA approval needed before sale; content and purity are left to the manufacturerCanada: a natural health product that must be registered. Erland tested exactly these Canadian products, which shows that registration does not mean each batch is checkedMuch of the EU, the UK and Australia: mainly a prescription medicine, though some countries also allow low-dose products to be sold as food supplementsJapan: it cannot be sold as a supplementChina: regulated as a health food
So the same 3 mg melatonin capsule bought in a US supermarket and in a European pharmacy may not be the same product at all: purity, dose, other ingredients and whether a doctor is involved all differ.
The surge in US child ingestions: what CDC 2022 MMWR counted was reports to poison control centers of children ingesting melatonin, 260,435 between 2012 and 2021, with the yearly number rising 530%; the rise in hospital stays and serious outcomes came mainly from accidental ingestion by children aged 5 and under. The report links this to rising melatonin sales and availability; candy-like gummies with a high dose per piece also make it easier for a child to eat many at once. Most children were fine, but in the same report 5 children needed mechanical ventilation and 2 died. Those two figures are the real weight of this issue, and most were fine should not cover them up. If a child who swallowed some is too drowsy to wake or is breathing abnormally, call emergency services now; even without symptoms, call poison control or an emergency department for advice.
What is still unknown about long-term use:
Randomized trial data beyond 12 weeks are scarceThe effect of long-term use in children on puberty and sexual development is unclear; the concern comes from melatonin's links to the reproductive hormone axisTolerance: some users say they need more and more, and trials have reached no consistent conclusionDependence and rebound on stopping: some worry about it, but data are scarce
Where "safe" ends:
Healthy adults, occasional use, < 5 mg a dose, for no more than 2 weeks: almost no serious side effects in short-term trials5 mg or more every night, long term: the boundary is unclear, and the concern outweighs the evidenceChildren, pregnant women and teenagers: only under a doctor's guidance, short term, and when neededAnyone taking fluvoxamine: do not combine them. Melatonin is broken down mainly by the liver enzyme CYP1A2, and fluvoxamine is one of its strongest inhibitors: the same tablet produces about an order of magnitude more exposure in the blood, and the European label for prescription melatonin says outright that the combination should be avoided. By the same metabolic route, other strong CYP1A2 inhibitors (such as ciprofloxacin and other quinolone antibiotics) also call for caution. This is the only interaction on this list with a hard number behind itPeople taking anticoagulants (such as warfarin), blood-pressure drugs, immunosuppressants or antiepileptic drugs should be careful, but to be clear, these rest only on case reports or theory (the Cochrane jet-lag review mentions case reports involving warfarin and epilepsy), and they carry far less weight than the line above
In practice · If you buy it, how to choose
If you must buy it, there are 4 criteria for choosing.1. Dose ≤ 1 mg: start at 0.3–0.5 mg and avoid products labeled 5–10 mg or high strength. If those are hard to find, cutting a 1 mg tablet into quarters gives about 0.25 mg, a workable compromise.
2. Third-party certification (USP / NSF / ConsumerLab): a USP Verified mark means the measured content matches the label, there are no heavy metals, and it meets GMP (good manufacturing practice); ConsumerLab.com needs a paid subscription, but its testing is credible; NSF Certified for Sport is the athlete-grade tier. Products without certification are likely to have the kinds of problems the Erland 2017 testing found.
3. A clean ingredient list:
What you want: melatonin plus a small amount of inactive ingredients (cellulose, magnesium stearate)What to avoid: sleep blends that mix several sleep substances (gamma-aminobutyric acid, ; 5-hydroxytryptophan, , a serotonin precursor; passionflower; valerian and so on). Their combined effect has not been tested, while the side-effect risks add upAbove all, avoid sleep blend formulas containing 5-HTP. The unlabeled serotonin in the Erland testing makes the same point: the more complex the formula, the fewer ingredients you can confirm. (That study did not trace the serotonin to 5-HTP as a raw material; these are two examples of one principle.)
4. Form and timing:
Sublingual tablets or sprays: absorbed quickly, suited to trouble falling asleepProlonged-release tablets: designed to keep blood levels up through the night, and prescribed in Europe for older people with insomnia; but they do nothing about apnea, anxiety or needing to urinate at night, the causes that break sleep upGummies: high doses and easy to eat too many; the Cohen 2023 testing measured gummies at 74%–347% of the labeled amount (with one product containing none at all), so the format itself is the least accurate tier. Keep them where children cannot reach themTiming: 30–60 minutes before bed, not right at bedtime, because it needs time to work
No brand list here, only criteria. No measured data on this site can support brand X is better quality: neither the Erland nor the Cohen testing ranked products by brand. More to the point, the CDC report above has just shown child ingestions rising sharply, and naming a children's product right after it would contradict that.
So take these three to the shelf. They work in another country, or another year:
1. Third-party certification such as USP / NSF, meaning measured content matches the label, no heavy metals, and GMP compliance
2. A clean ingredient list: pure melatonin plus a little inactive filler, no sleep blend
3. A dose of ≤ 1 mg per unit
A product that meets all three is more reliable than any brand's reputation, whatever it is called. Where melatonin is prescription-only (much of the EU, the UK, Australia), going through a doctor meets the first two for you.
The long-term goal is not to depend on it: reset the body clock with light, a fixed schedule and , and move melatonin back to emergency use.
Chapter 5
Stronger interventions than melatonin
To sleep better, the strongest evidence, ahead of every supplement, is for a behavioral treatment: cognitive behavioral therapy for insomnia (). The main guidelines all make it the first step for chronic insomnia.
A few other things (getting up at the same time every day, going outdoors into morning light, cooling the bedroom, and no caffeine for at least 6 hours before bed) have not been tested much on their own, but they make sense by mechanism: they change the input signals, telling the what time it is and letting core temperature fall when it should. Melatonin is just one molecule released at the end of that chain.
A supplement moves one variable at a time, while trouble sleeping usually means several things are off at once: rhythm, environment, mind. So first check which link you are stuck on, then decide whether to go looking for a bottle on the shelf.
A few other things (getting up at the same time every day, going outdoors into morning light, cooling the bedroom, and no caffeine for at least 6 hours before bed) have not been tested much on their own, but they make sense by mechanism: they change the input signals, telling the what time it is and letting core temperature fall when it should. Melatonin is just one molecule released at the end of that chain.
A supplement moves one variable at a time, while trouble sleeping usually means several things are off at once: rhythm, environment, mind. So first check which link you are stuck on, then decide whether to go looking for a bottle on the shelf.
Evidence · CBT-I and four basics
The one with the strongest evidence, and four basics that make sense by mechanism1. Behavioral therapy (): the best-supported option, far ahead of any supplement. Trauer 2015 (Annals of Internal Medicine) pooled 20 randomized trials: compared with control groups, the time taken to fall asleep shortened by about 19 minutes, time awake after first falling asleep fell by about 26 minutes, and sleep efficiency rose by about 10 percentage points; total sleep time rose by only 7.6 minutes, which was not statistically significant. An evidence review (Morin 2006) shows the improvement holds at follow-up, the opposite of sleeping pills. Digital versions (Sleepio, SHUTi) also work.
2. A fixed wake time (anchoring the body clock): sleep doctors generally hold that it matters more than a fixed bedtime. Get up at the same time every day, keep weekend drift under 1 hour, and sleep pressure and the body clock line up, so the time you fall asleep adjusts on its own.
3. 10–30 minutes of bright light after getting up: outdoors beats indoors (10000+ lux versus about 500). The anchors morning, and by normal physiology melatonin starts to rise about 14–16 hours after you get up. In a northern winter, or if you spend the whole day indoors, a light-therapy lamp (10000 lux for 30 minutes) can stand in.
4. A bedroom at 18–20°C: core temperature has to fall for sleep to come easily, and a room that is too warm is an often-overlooked link. A cooler mattress, a fan, or air conditioning set to 18–19°C all help with this step.
5. Caffeine stopped at least 6 hours before bed: Drake 2013 gave 12 normal sleepers 400 mg of caffeine at 0, 3 or 6 hours before bed, and at all three times they slept worse than on placebo; by the monitor, even the dose taken 6 hours before bed cut sleep by more than 1 hour. The authors' advice is to avoid it for at least 6 hours before bed. If you usually go to bed at 22–23, stop after 2 pm. Caffeine's half-life averages about 4–5 hours, and runs much longer in people whose liver enzyme for breaking it down (CYP1A2) is naturally slow: for a slow metabolizer at 7 hours, coffee drunk at 4 pm still leaves half its caffeine in the blood at 11 pm. I can drink coffee and still fall asleep is not the same as sleeping well.
Why exactly these five
Set them against the chain on the page about melatonin's receptor mechanism, and each blocks a different link, with almost no overlap:
A fixed wake time plus morning light act on the most upstream link: the ipRGCs report it is daybreak to the SCN, and the SCN sets that day's starting gun from it. Morning light and evening blue light use the same pathway in opposite directions, so these are not a vague more sun is good for you tip; they set the clock directlyCooling the bedroom acts on the most downstream link: melatonin relaxes the skin's blood vessels so heat can leave and core temperature can fall. When the room is too hot, the heat cannot leave and this step jams. However much melatonin you take, the signal arrives but cannot be carried outA caffeine cut-off acts on a completely separate line: adenosine. Adenosine is the sleep pressure line; caffeine occupies adenosine's seat, so the pressure has built up but the body never gets the notice. This line runs in parallel with melatonin, and neither can stand in for the otherCBT-I acts on the wake drive itself: daytime hyperarousal and anxiety about not sleeping both add weight to the wake side. Melatonin can only press the wake drive down a little; CBT-I takes away the hand that keeps adding weight
So these five are not pick one of five. They are five different blockages along the chain. Fix the link where you are stuck, which is also why a single tablet rarely covers it: it matches only one of the links.
trauer-2015-anninternmed-cbtimorin-2006-cbt-i-meta
Evidence · Other habits and the supplement shelf
Lifestyle habits with some research behind them6. Regular aerobic exercise: 30 minutes or more a day, but not within 2–3 hours of bedtime. In Kredlow 2015's , a single bout of exercise brought only small improvements, while regular exercise did more, mainly by helping people fall asleep faster; very late, high-intensity exercise can disturb sleep instead.
7. Drinking less alcohol: alcohol helps you fall asleep faster and sleep deeply in the first half of the night, but the second half is broken up, the first period of rapid eye movement () sleep is delayed, and at moderate or higher amounts REM across the whole night falls (Ebrahim 2013, a review).
8. Finish dinner 3 hours before bed, and do not drink large amounts of water before sleep: a stomach still digesting affects sleep, and getting up to urinate breaks up the night.
9. A dark, quiet bedroom: light in the bedroom also suppresses melatonin, and the brighter it is, the more it does. Earplugs, an eye mask and blackout curtains all help.
Supplements with limited evidence
Magnesium (glycinate or citrate, 200–400 mg): a few small randomized trials with mixed results; a meta-analysis of trials in older adults (Mah 2021) rated the evidence low to very low. Also, magnesium from supplements above 350 mg a day exceeds the tolerable upper intake level () and should be used under a doctor's guidanceGlycine (3 g before bed): one small trial (Yamadera 2007) found better subjective sleep quality; it still needs to be repeatedTheanine (L-theanine, 200 mg): mostly small trials; a subjective sense of relaxed but not drowsy, worth trying for people anxious at bedtimeValerian: mixed data, with a traditional history of use in EuropeMelatonin (0.3–1 mg): good evidence for jet lag, weak guideline recommendations for a few rhythm disorders, and a small effect on ordinary insomnia
Expensive and popular, but with weak or no support:
Cannabidiol (CBD): weak randomized-trial data5-hydroxytryptophan (, the precursor of serotonin): taken with antidepressants it carries a risk of serotonin syndrome; do not take it on your ownGamma-aminobutyric acid () supplements: GABA hardly crosses the blood-brain barrier, so taking it by mouth does almost nothingSleep blend supplements: several ingredients mixed together, with side-effect risks adding up
Why oral GABA does almost nothing: this one deserves a closer look
It is the easiest claim on the whole shelf to see through, and one of the most often sold. Gamma-aminobutyric acid (GABA) really is the brain's main inhibitory signal, and saying it calms the nerves is not wrong. The problem is that it never reaches the scene. The cells lining the brain's blood vessels are joined extremely tightly, with a layer of glial-cell feet wrapped around the outside. This wall, the blood-brain barrier, lets only two kinds of things through: those fat-soluble enough to dissolve straight through cell membranes, and those met by a dedicated transporter protein. GABA qualifies for neither: it is charged and water-soluble, and the brain side has no machine to haul it from the blood into the brain (the traffic runs the other way; the brain's GABA is made on site).
So the GABA you swallow stays in the blood and is eventually broken down, while the level on the brain side barely moves. The relaxed feeling a few people report may come from an effect on nerve endings in the gut plus expectation, rather than from topping up the brain.
This reasoning is worth keeping not because of GABA itself, but because it gives you a ruler you can reuse: whenever you see a claim to directly supplement a neurotransmitter, ask first, can this thing cross the blood-brain barrier? The same ruler measures serotonin too: on the page about how melatonin is made, the synthesis chain shows that supplying a raw material is not the same as supplying the finished product.
Most sleep problems come from habits of modern life that fight the body clock. Fixing behavior and environment first does far more than any supplement, melatonin included.
kredlow-2015-exercise-sleep-metaebrahim-2013-alcohol-sleepmah-2021-magnesium-insomnia-older-adultsyamadera-2007-glycine-sleep
In practice · A 3-day reset without supplements
If your sleep is bad, here is a 3-day reset that does not rely on supplements.Day 1 · Screens off, wake time anchored
After 8 pm, no bright overhead lights; use a table lamp with a warm bulb instead9 pm: TV off, phone put away10 pm: set the bedroom to 18–19°CDo not check the time; turn the alarm clock to face away from youTomorrow's wake time = your weekday wake time, weekends included
Day 2 · Morning light, no catch-up sleep
Within 30 minutes of getting up, get 10–20 minutes of outdoor light (even on an overcast day it is > 1000 lux outdoors)No catch-up sleep, however badly you slept the night beforeDaytime naps < 30 minutes and no later than 2 pmNo caffeine after 2 pm (with a usual bedtime of 22–23, that leaves at least 6 hours before sleep)Dinner at 6–7 pm, then water onlyScreens down by 9 pmInto bed at 10:30
Day 3 · Consolidate and assess
Repeat Day 2In the evening, note three things: what time you fell asleep, how many times you woke, and how you felt in the morningAn improvement of ≥ 30%: you have found the right lever, so run the pattern for another 2 weeks. There is no what percentage of people get better figure here, because no source on this site supports oneNo improvement: it may be worth checking for obstructive sleep apnea (, where the airway repeatedly collapses during sleep and you wake gasping, often with snoring and daytime tiredness), or seeing a doctor about or a psychiatric assessment
Key principles:
No reliance on supplements or drugsBehavior first, not a pill at nightMorning light is the most important item hereA fixed wake time matters more than a fixed bedtime
Why do these first and consider 5 mg of melatonin only afterward? Because melatonin adjusts one variable (the signal), while insomnia usually involves several at once: rhythm, sleep habits, environment and mind. One pill cannot adjust that many variables.
Chapter 6
Should you take it, and how
Melatonin is not a sleep hormone supplement; it is a signal that moves the body clock. In the right situation, at a small dose and the right time, it does help; treated as an all-purpose sleep aid, it will mostly disappoint.
The best evidence is for jet lag across several time zones; a few rhythm disorders diagnosed by a doctor (such as the delayed type, where the whole timetable runs late) have weak guideline recommendations. Taking it for chronic insomnia before trying cognitive behavioral therapy for insomnia () skips the more effective option.
Two things to remember: people taking the antidepressant fluvoxamine should not combine the two, and if there are children at home, store it like a medicine.
The best evidence is for jet lag across several time zones; a few rhythm disorders diagnosed by a doctor (such as the delayed type, where the whole timetable runs late) have weak guideline recommendations. Taking it for chronic insomnia before trying cognitive behavioral therapy for insomnia () skips the more effective option.
Two things to remember: people taking the antidepressant fluvoxamine should not combine the two, and if there are children at home, store it like a medicine.
In practice · Who it suits, dose and timing
A practical decision checklist for melatonin.People who might consider it (usually starting at 0.3–1 mg, 30–60 minutes before bed):
Jet lag across five or more time zones: the best-supported use (the Cochrane review)Long-term shift work: limited help and mixed study results (Sack 2007); use it together with light managementDelayed sleep-wake phase disorder (DSPD) diagnosed by a doctor: a weak recommendation from AASM 2015, taken at set times under a doctor's guidanceNon-24-hour rhythm disorder in blind people: also a weak recommendation from AASM 2015. Two things need keeping apart here: what the FDA approved is tasimelteon (brand name Hetlioz), an MT1/MT2 receptor agonist; it is not melatonin. Melatonin itself is used off-label here and needs specialist supervision. Do not read this line as melatonin is FDA-approved: the point this story keeps making is that in the US melatonin is classed as a dietary supplement, which the FDA neither approves nor overseesOlder people who struggle to fall asleep: a small dose is worth trying (in Zhdanova 2001, in people over 50, 0.3 mg restored sleep efficiency)Children and adolescents with a neurological disorder and irregular sleep: a weak recommendation from AASM 2015, used under a doctor's guidance
People it does not suit:
Healthy adults taking one every night as insurance: no evidence, and possible tolerance or dependenceChronic insomnia without having tried : this skips the stronger optionHealthy children with trouble falling asleep: behavioral approaches, not gummiesOlder people with dementia: AASM 2015 advises against itPregnancy and breastfeeding: not enough safety data; use with cautionAnyone taking fluvoxamine or another strong CYP1A2 inhibitor (ciprofloxacin and other quinolones): do not combine them. Melatonin is cleared mainly by CYP1A2, and the combination raises blood exposure by an order of magnitude; the European label for prescription melatonin says exactly that the combination should be avoidedPeople taking anticoagulants, blood-pressure drugs, antiepileptic drugs or immunosuppressants: a risk of interaction (these rest only on case reports or theory, and are softer than the line above)Insomnia that mixes trouble falling asleep, early waking and repeated waking: ordinary immediate-release melatonin does little; look for the causeA diagnosed depression or anxiety disorder in which insomnia is one symptom: treat the underlying condition rather than taking melatonin
Dose principles:
Start with 0.3–0.5 mg (a sensible low dose)1 mg if neededRarely any need to go above 3 mg (beyond that, a higher dose no longer brings more effect)Do not take 5–10 mg "strong" products every night for long periods (no extra benefit, more side effects). The one exception is jet lag: in the Cochrane data 0.5–5 mg worked about equally well, so a short trip on 5 mg is not out of bounds, but that is a few nights, not every night
Timing:
Most situations: 30–60 minutes before going to sleepJet lag: after arrival, close to local bedtime (about 10 pm to midnight); do not move it up to early eveningDelayed-type rhythm disorder or changing shift direction (moving the clock earlier): about 4–6 hours before the target sleep time, based on Lewy 1998's phase response curve; the exact hour is best set by a doctor from your melatonin onset (DLMO)Daytime sleep after a night shift: a small dose on getting home (about 6–7 am); results are mixed, and do not take it if you have to drive
How it fits with other steps: a bright screen at night pushes melatonin's onset later, so rather than taking a tablet to cancel it out, put the screen down first. Morning light with a fixed wake time, and a suitable bedroom, are more basic steps than melatonin. The first choice for chronic insomnia remains a 6–8 week course of CBT-I.
Handling long-term use (a cautious approach, not figures from trials):
After 2–4 weeks, reassess whether you still need itAt 3 months, reassess again; most people should move to a behavioral planTrial data on taking it every night for more than 6 months are scarce, so it is best not to take it that long
lewy-1998-phase-response
In practice · Is it actually working for you
How can you tell whether melatonin really works for you?A more objective marker: taking < 30 minutes to fall asleep (compared with before)How you feel: alert in the morning, not groggyLasting more than 1 week, not a single night of falling asleep because I was in a good mood
What a placebo effect looks like: expecting tonight I will definitely sleep eases anxiety a little, and so you fall asleep. Taking anything can bring a spell of subjective improvement, but it does not last; once the novelty wears off, so does the effect.
Signs that it is more likely really working:
Crossing time zones (the situation the mechanism explains best)A specific rhythm disorder, with the dose taken at the right timeOlder age, with naturally low melatoninSteady improvement lasting 4 weeks or moreSymptoms coming back after stopping (not withdrawal, but the original problem still being there)
A few questions to ask yourself:
1. Is it trouble falling asleep, or waking several times in the night? For trouble falling asleep melatonin may help; for repeated waking, ordinary immediate-release melatonin does little.
2. Is it sleeping late and waking late, or tired however long you sleep? Sleeping and waking late (the delayed type) can try melatonin plus morning light; being tired all day calls for checking for obstructive sleep apnea (), an underactive thyroid, depression, iron deficiency and vitamin B12 deficiency.
3. Do you sleep 5–6 hours and not feel tired? A few people naturally need only about 6 hours (natural short sleepers, who are rare). That is not an illness and needs no treatment.
Clear signals to stop taking melatonin:
4 weeks of use with no change in how you feelStill no effect after going up to 3 mg or moreNext-day grogginess, headache or low moodClearly more nightmaresA racing heart or palpitationsA clash with a medicine you must take (such as warfarin)
When you find it does not work, do not keep raising the dose. Go back to the behavioral basics and look for the real reason you are sleeping badly. One pill cannot fix a disorder that runs through environment, rhythm, mind and body all at once.
References · 15
- Brzezinski, A., et al. (2005). Effects of exogenous melatonin on sleep: a meta-analysis. Sleep Medicine Reviews, 9(1), 41–50. 17 studies, 284 subjects: melatonin reduced sleep onset latency by 4.0 min (95% CI 2.5-5.4), increased sleep efficiency by 2.2% (0.2-4.2) and total sleep by 12.8 min (2.9-22.8); in the 15 studies of healthy people or people with insomnia only: 3.9 min, 3.1% and 13.7 min (abstract, PMID 15649737). 10.1016/j.smrv.2004.06.004
- Cajochen, C., Kräuchi, K., & Wirz-Justice, A. (2003). Role of melatonin in the regulation of human circadian rhythms and sleep. Journal of Neuroendocrinology, 15(4), 432-437. Review of endogenous melatonin as the internal signal of biological night: secretion is driven by the suprachiasmatic nucleus and suppressed by light, and the hormone feeds back on the SCN through MT1 and MT2 receptors, with sleep-promoting effects that track its thermoregulatory action rather than a hypnotic one. 10.1046/j.1365-2826.2003.00989.x
- Chang, A. M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceedings of the National Academy of Sciences, 112(4), 1232-1237. In a controlled in-laboratory crossover, reading from a light-emitting eReader for four hours before bed across five consecutive evenings suppressed evening melatonin, delayed circadian timing and sleep onset, reduced REM sleep, and left participants less alert the next morning, compared with reading a printed book. Full text: 12 healthy young adults (6 women), 14-day inpatient randomized crossover; about 4 h of reading before bedtime in otherwise very dim room light on 5 consecutive evenings per condition (the eReader held at 30-50 photopic lux in the angle of gaze; the printed book reflected about 0.9 lux). On night 5 the eReader suppressed evening melatonin by 55.12 ± 20.12% (print book: none); dim-light melatonin onset was more than 1.5 h later (22:31 vs 21:01); sleep latency was nearly 10 min longer (25.65 vs 15.75 min); total sleep time and sleep efficiency did not differ (full text, PMC4313820; abstract, PMID 25535358). 10.1073/pnas.1418490112
- Lelak, K., Vohra, V., Neuman, M. I., Toce, M. S., & Sethuraman, U. (2022). Pediatric melatonin ingestions — United States, 2012–2021. MMWR Morbidity and Mortality Weekly Report, 71(22), 725–729. National Poison Data System 2012-2021, ages 19 and under: 260,435 pediatric melatonin ingestions, the annual number up 530%; 4.9% of all pediatric ingestions reported in 2021 vs 0.6% in 2012; hospitalizations and serious outcomes rose, mainly from unintentional ingestions in children aged 5 or under; 5 children needed mechanical ventilation and 2 died. US over-the-counter melatonin sales rose from $285 million (2016) to $821 million (2020) (abstract, PMID 35653284). 10.15585/mmwr.mm7122a1
- Auger, R. R., et al. (2015). Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders. Journal of Clinical Sleep Medicine, 11(10), 1199–1236. Scope: intrinsic circadian rhythm sleep-wake disorders only (advanced and delayed sleep-wake phase disorder, non-24-hour and irregular sleep-wake rhythm disorder); jet lag and shift work are not among them. Strategically timed melatonin is endorsed only at the second-tier degree of confidence, for delayed sleep-wake phase disorder, blind adults with non-24 and children/adolescents with irregular rhythm plus neurological disorders; recommendations AGAINST melatonin (second tier) and sleep-promoting drugs (first tier) in demented elderly patients. The abstract gives no melatonin dose (abstract, PMID 26414986). 10.5664/jcsm.5100
- Zhdanova, I. V., Wurtman, R. J., Regan, M. M., Taylor, J. A., Shi, J. P., & Leclair, O. U. (2001). Melatonin treatment for age-related insomnia. The Journal of Clinical Endocrinology & Metabolism, 86(10), 4727–4730. Double-blind, placebo-controlled crossover in people over 50: 15 normal sleepers and 15 with actigraphically confirmed low sleep efficiency each received placebo and melatonin 0.1, 0.3 and 3.0 mg 30 min before bedtime for a week, with 1-week washouts; polysomnography on the last 3 nights. 0.3 mg restored sleep efficiency (P < 0.0001) and brought plasma melatonin to normal; 3.0 mg (like 0.1 mg) also improved sleep but induced hypothermia and left plasma melatonin elevated into the daylight hours; normal sleepers were unaffected by any dose (abstract, PMID 11600532). 10.1210/jcem.86.10.7901
- Dollins, A. B., Zhdanova, I. V., Wurtman, R. J., Lynch, H. J., & Deng, M. H. (1994). Effect of inducing nocturnal serum melatonin concentrations in daytime on sleep, mood, body temperature, and performance. Proceedings of the National Academy of Sciences, 91(5), 1824-1828. Twenty healthy men received 0.1, 0.3, 1.0 or 10 mg of oral melatonin at noon. Doses from 0.1 mg upward raised daytime serum melatonin into the normal nocturnal range and shortened sleep latency; the authors found no dose-response advantage to the larger doses. 10.1073/pnas.91.5.1824
- Herxheimer, A., & Petrie, K. J. (2002). Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews, (2), CD001520. 10 trials in airline passengers, staff or military personnel (all vs placebo, one also vs zolpidem): 9 of 10 found that melatonin taken close to target bedtime at the destination (10 pm to midnight) decreased jet lag from flights crossing 5 or more time zones. Daily doses of 0.5-5 mg were similarly effective (5 mg gives faster, better sleep than 0.5 mg); above 5 mg no more effective; 2 mg slow-release was relatively ineffective. NNT 2. Benefit is likely greater the more zones crossed and less for westward flights; taken early in the day it can cause sleepiness and delay adaptation; case reports suggest harm in people with epilepsy and those on warfarin (abstract, PMID 12076414). 10.1002/14651858.CD001520
- Sack, R. L., Auckley, D., Auger, R. R., Carskadon, M. A., Wright, K. P., Jr., Vitiello, M. V., & Zhdanova, I. V. (2007). Circadian rhythm sleep disorders: part I, basic principles, shift work and jet lag disorders. An American Academy of Sleep Medicine review. Sleep, 30(11), 1460-1483. Evidence review for the AASM; treatments fall into prescribed sleep scheduling, circadian phase shifting, and symptomatic hypnotics or stimulants. On melatonin before daytime sleep in night workers (full text, section 6.4.2.2): two shift-work simulation studies and several field studies at 0.5-10 mg, none in workers formally diagnosed with shift work disorder; its conclusion is that the evidence of benefit is mixed, that variable schedules, doses and timing make firm conclusions difficult, and that any improvement in day sleep may be a hypnotic as well as a phase-shifting effect (abstract, PMID 18041480; full text, PMC2082105). 10.1093/sleep/30.11.1460
- Erland, L. A. E., & Saxena, P. K. (2017). Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content. Journal of Clinical Sleep Medicine, 13(2), 275–281. 10.5664/jcsm.6462
- Cohen, P. A., Avula, B., Wang, Y. H., Katragunta, K., & Khan, I. (2023). Quantity of melatonin and CBD in melatonin gummies sold in the US. JAMA, 329(16), 1401-1402. Chemical analysis of 25 melatonin gummy products: one contained no melatonin at all, and the quantity of melatonin in the rest ranged from 74% to 347% of the labelled amount. 10.1001/jama.2023.2296
- Härtter, S., Grözinger, M., Weigmann, H., Röschke, J., & Hiemke, C. (2000). Increased bioavailability of oral melatonin after fluvoxamine coadministration. Clinical Pharmacology and Therapeutics, 67(1), 1-6. Coadministration of fluvoxamine, a strong CYP1A2 inhibitor, raised oral melatonin exposure by roughly an order of magnitude. Melatonin is cleared mainly by CYP1A2, so the interaction extends in principle to other strong inhibitors of that enzyme. 10.1067/mcp.2000.104071
- Qaseem, A., Kansagara, D., Forciea, M. A., Cooke, M., & Denberg, T. D., for the Clinical Guidelines Committee of the American College of Physicians. (2016). Management of chronic insomnia disorder in adults: a clinical practice guideline from the American College of Physicians. Annals of Internal Medicine, 165(2), 125-133. ACP recommends CBT-I as the first-line treatment for chronic insomnia in adults. 10.7326/M15-2175
- Edinger, J. D., Arnedt, J. T., Bertisch, S. M., et al. (2021). Behavioral and psychological treatments for chronic insomnia disorder in adults: an American Academy of Sleep Medicine clinical practice guideline. Journal of Clinical Sleep Medicine, 17(2), 255-262. 10.5664/jcsm.8986
- Drake, C., Roehrs, T., Shambroom, J., & Roth, T. (2013). Caffeine effects on sleep taken 0, 3 or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 9(11), 1195-1200. Randomized, double-blind, placebo-controlled Latin-square crossover in 12 healthy normal sleepers: one fixed 400 mg dose of caffeine (the authors call it moderate) at 0, 3 or 6 h before habitual bedtime vs placebo, sleep measured at home by diary and a portable monitor. All three timings disrupted sleep vs placebo (P < 0.05). By the objective monitor, even at 6 h caffeine reduced sleep by more than 1 hour; by diary, the 6-h reduction in total sleep time (41 min) only approached significance (p = 0.08). The authors conclude that substantial caffeine should be avoided for a minimum of 6 hours before bedtime, and that afternoon caffeine should at least be restricted to before 17:00 (abstract, PMID 24235903; full text, PMC3805807). 10.5664/jcsm.3170