Shift Work · Circadian Misalignment

regulates · 5

• →Heart

  Shift work is IARC 2A and long-term CHD ↑19% (Vetter 2016 JAMA) — circadian misalignment stacks sympathetic surge + inflammation + MetSyn.

  RCT · B

• →Melatonin

  The core problem in shift work is not less sleep but an internal clock out of phase with the light outside: the SCN resets on light and melatonin is the darkness signal it sends. IARC classes circadian disruption as probably carcinogenic (2A), alongside red meat — a biological limit, not a matter of toughness.

  GUIDE · AREVIEW · A

• ↔Fasting & TRE

  Time-restricted eating depends on where the window sits in the body clock: an early window (7 AM-3 PM) shows the strongest metabolic effect, and shift work decouples that window from the light-dark cycle.

  RCT · BCOHORT · B

• ←Menstrual Cycle

  The HPO axis hangs off the body clock, so time-zone shifts and rotating shifts disturb the cycle — the same family of causes as stress, energy shortfall and rapid weight change: all of them telling the hypothalamus that now is a bad time.

  REVIEW · A

• →Caffeine + L-Theanine

  Caffeine is a timing input too: it does more than keep you awake, it signals the SCN. For shift workers the hour matters more than the dose — keep it to the front of the shift so it does not push an already-shifted clock further.

  COHORT · BREVIEW · A