How poor sleep shifts hormones toward overeating.
What the evidence says
- Under controlled intake, sleep restriction increases ghrelin (hunger) and decreases leptin (satiety) — the condition governs the direction: `csh03` fixed food and activity, so nobody could overeat. When intake is free the hormones read the opposite way — see the paradox below before citing this bullet[1]
- The exposure that produced these shifts was 2 days at 4 hours against 2 days at 10 hours (the 4-hour and 10-hour figures are not in `csh03`’s held abstract, which says only ”2 days of sleep restriction and 2 days of sleep extension”; full text is not held) — this bullet read ”even mild sleep debt… within days” until 2026-09-02, which generalises both the dose and the duration beyond what was tested[1]
- In that same controlled protocol, appetite increases specifically for high-carb, calorie-dense foods[1]
- Under CONTROLLED intake, poor sleep produces a hormonal environment favouring overeating — but see the paradox below: when intake is free, the overeating happens anyway and the hormones read the opposite way[1]
- *The authors’ own stated limitation, held for the first time on 2026-09-02 and carried by no file until now: ”The study included only 12 young men and did not measure energy expenditure.” So `csh03` cannot speak to energy balance. It measured hormones and subjective ratings of hunger and appetite — not intake, not expenditure, not weight. A page may say sleep restriction shifted appetite hormones and self-reported hunger in these twelve men. It may not say sleep loss makes people gain weight on this citation*[1]
- Sleep-deprived individuals consume 42% more calories as after-dinner snacks, with after-dinner carbohydrate at 118.4 ± 60.0 g on 5h sleep against 75.2 ± 43.6 g on 9h (P = 0.001) — the paper reports those two figures and no percentage between them; the ~57% rise is arithmetic on them, not a result it states[2]
- Five days of insufficient sleep produced 0.82 ± 0.47 kg of weight gain[2]
- The hormonal paradox, and it is the file’s most important finding: in that same study leptin rose 22% (P < 0.05), ghrelin FELL 30% (P < 0.001) and peptide YY rose 32% (P < 0.01) — every signal reading energy surplus — and participants overate regardless[2]
- Sex difference: women maintained weight on adequate sleep but gained on insufficient sleep, and insufficient sleep reduced dietary restraint more in women[2]
- Increased snack consumption occurs particularly in evening hours (7pm-7am)[3]
- Neural mechanism: sleep deprivation impairs frontal cortex evaluation regions while amplifying amygdala reactivity to food — “double hit” of increased desire + decreased control[4]
- The effect is not hunger-driven: hunger levels don’t differ between sleep-deprived and rested conditions (p=0.28) — it’s a neural bias, not metabolic[4]
- Sleep restriction over 5 nights selectively increases brain response to unhealthy foods without affecting response to healthy foods[5]
- ”eat more” is `csh06` — 42% more calories as after-dinner snacks, and after-dinner carbohydrate at 118.4 ± 60.0 g on 5h against 75.2 ± 43.6 g on 9h (P = 0.001), under free eating. Do not write a percentage for the carbohydrate rise: the paper states neither one.
- ”without feeling hungrier” is `csh07` — hunger ratings that ”did not differ statistically (p=0.28) between sleep deprived (47.7 ± 25.53 mm) and rested (39.7 ± 24.0 mm)”. Those ratings were taken preceding an fMRI scan, under a standardized eating schedule, in a study of food-desirability ratings rather than of intake.