Full mechanism, in text

Why insomnia keeps going

1 · Hyperarousal model · insomnia is not just low sleep

People with insomnia stay hyperaroused around the clock, with raised cognitive and physiological arousal, and cannot relax enough to sleep.The core of insomnia is not 'insufficient sleep' but hyperarousal — 24-hour elevated cognitive and physiological arousal:

Cognitive: rumination, preoccupation with sleep, catastrophizing about not sleepingCortical: EEG shows more beta/gamma waves at sleep onset (more wake-like), reduced slow-wave sleepPhysiological: reduced (sympathetic dominance), disrupted cortisol rhythm, elevated core temperatureMetabolic: PET shows higher glucose metabolism during NREM in insomniacs (brain doesn't 'shut down')
Insomniacs don't 'can't sleep'; they can't relax enough to sleep. This is why hypnotics (increase sleep quantity but don't reduce arousal) underperform long-term — they treat the symptom, not the mechanism.

2 · 3P model · predisposing/precipitating/perpetuating

In the 3P model, once the trigger has passed, habits adopted to cope, such as going to bed early, sleeping in and napping, keep insomnia going on its own.Spielman's 3P model explains how acute insomnia becomes chronic:

1. Predisposing: genetics (high arousal trait), personality (neuroticism/perfectionism), family history
2. Precipitating: triggering event — stress, illness, bereavement, shift work, increased caffeine. Acute insomnia begins
3. Perpetuating: this is 's target — behaviors adopted to cope: spending more time in bed 'catching up', sleeping in, napping, using alcohol to sleep, working/phone in bed

Key insight: the precipitating event may be long gone, but perpetuating factors keep insomnia self-sustaining. You go to bed early because of insomnia, spend more time awake in bed, bed becomes conditioned to wakefulness, and insomnia becomes chronic.

3 · Stimulus control · bed = sleep

Stimulus control re-establishes the conditioned link between bed and sleep by cutting time awake in bed, such as getting up after 20 minutes awake.Stimulus control therapy (Bootzin 1972) is a core technique, aiming to re-establish the 'bed = sleep' conditioned association:

1. Go to bed only when sleepy (not because 'it's time')
2. Use bed only for sleep (no work, phone, TV in bed)
3. If awake for 20 minutes, get up — go to another room, do a quiet activity (dim light reading), return when sleepy
4. Wake at a fixed time regardless of sleep duration (including weekends!)
5. No daytime naps (or limit to 20 min, before 3pm)

Principle: repeated 'bed-awake' pairings weaken the sleep conditioned response. By reducing time awake in bed, you re-establish 'get in bed → fall asleep quickly'.

It's hard. It works.

4 · Sleep restriction · build sleep drive

Sleep restriction cuts time in bed down to actual sleep time, which increases sleep drive and sleep efficiency and consolidates sleep.Sleep restriction therapy (Spielman) is counterintuitive but most effective:

1. Calculate your actual average sleep time (not time in bed)
2. Limit time in bed to this number (but no less than 5.5 hours)
3. Fixed wake time; bedtime = wake time − restricted window
4. Weekly adjust based on sleep efficiency (actual sleep/time in bed): >85% → add 15 min; <80% → subtract 15 min

Principle: insomniacs spend too much time in bed 'trying to sleep', causing fragmented shallow sleep. Restricting time in bed increases sleep drive (adenosine accumulation) and sleep efficiency, consolidating sleep.

First 1-2 weeks feel sleepier (normal), but sleep quality and efficiency improve significantly. : 70-80% of insomniacs show clinical improvement, effects persist >1 year, superior to long-term hypnotic use.

Full mechanism, in text

1 · Hyperarousal model · insomnia is not just low sleep

2 · 3P model · predisposing/precipitating/perpetuating

3 · Stimulus control · bed = sleep

4 · Sleep restriction · build sleep drive

CBT-I · 3P model & hyperarousal

Full mechanism, in text

1 · Hyperarousal model · insomnia is not just low sleep

2 · 3P model · predisposing/precipitating/perpetuating

3 · Stimulus control · bed = sleep

4 · Sleep restriction · build sleep drive

CBT-I · 3P model & hyperarousal