Sleep and Metabolism: Leptin, Ghrelin, and Appetite Dysregulation
One week of 5h/night sleep reduces leptin 18% and increases ghrelin 28%, creating a 24% increase in hunger; subjects preferentially craved high-carbohydrate, calorie-dense foods.
| Measure | Value | Unit | Notes |
|---|---|---|---|
| Leptin reduction after sleep restriction | 18 | % decrease | 5h/night for 6 nights (Spiegel 2004); leptin = satiety signal from adipose tissue |
| Ghrelin increase after sleep restriction | 28 | % increase | Ghrelin = hunger hormone from stomach; stimulates appetite and fat storage |
| Subjective hunger increase | 24 | % increase | Subjects reported significantly higher appetite for calorie-dense foods |
| Caloric intake when sleep-deprived | +250–500 | kcal/day | Multiple studies; caloric increase exceeds any energy expenditure from extended waking |
| Obesity risk at <6h sleep | 1.55× | higher risk | Meta-analysis Cappuccio 2008; 15 prospective studies, n=244,000+ participants |
The Leptin-Ghrelin Axis
Two hormones play central roles in appetite regulation and are directly affected by sleep:
Leptin: secreted by adipose (fat) tissue, leptin signals satiety to the hypothalamus. High leptin = feeling full; low leptin = hunger drive. Leptin secretion follows a circadian rhythm with peak levels during nocturnal sleep.
Ghrelin: produced primarily by the stomach, ghrelin is the primary hunger-stimulating hormone. It rises before meals and falls after eating. Like leptin, it has circadian rhythm components.
Spiegel et al. (2004) restricted 12 healthy young men to 5 hours of sleep per night for 6 nights. The results were striking:
| Hormone | Change |
|---|---|
| Leptin | −18% |
| Ghrelin | +28% |
| Subjective hunger | +24% |
| Appetite for calorie-dense food | +34% |
Subjects specifically craved high-carbohydrate and sweet foods — consistent with the brain seeking quick energy to compensate for perceived energy shortage signals.
The Obesity Connection
Taheri et al. (2004) analyzed data from 1,024 participants in the Wisconsin Sleep Cohort and found a dose-response relationship between shorter sleep duration and higher BMI:
- 8h sleep: average BMI ~25
- 7h sleep: BMI slightly higher
- 6h sleep: ~24% higher odds of obesity
- 5h sleep: ~50% higher odds of obesity
This relationship held after controlling for physical activity, diet reporting, and other confounders. The hormonal mechanism (lower leptin, higher ghrelin in short sleepers) was directly measured and correlated with BMI.
Sleep Restriction Undermines Dieting
Nedeltcheva et al. (2010) conducted a crossover intervention study of critical importance for weight management: subjects attempting caloric restriction lost 55% less fat when sleep-restricted (5.5h/night) compared to when allowed adequate sleep (8.5h/night) — despite eating the same calories. The restricted sleep group lost primarily lean muscle mass instead.
This suggests that sleep quality is as important as caloric restriction for body composition outcomes — inadequate sleep may paradoxically preserve fat stores while sacrificing lean tissue.
Insulin Resistance
Sleep restriction also rapidly induces insulin resistance. Van Cauter’s group demonstrated that restricting sleep to 4 hours for 6 nights reduced insulin sensitivity by 30% — comparable to gaining 10kg of body weight. This effect is independent of caloric intake and exercise and can manifest within days of sleep restriction.
Related Pages
Sources
- Spiegel K et al. — Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger. Ann Intern Med (2004)
- Taheri S et al. — Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index. PLoS Med (2004)
- Nedeltcheva AV et al. — Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med (2010)
- Cappuccio FP et al. — Meta-analysis of short sleep duration and obesity in children and adults. Sleep (2008)
Frequently Asked Questions
Why does sleep deprivation cause weight gain?
Sleep restriction disrupts appetite hormones: leptin (satiety signal) falls and ghrelin (hunger signal) rises, creating a state of increased hunger for calorie-dense foods. Additionally, the extra awake hours provide more time and opportunity to eat, and sleep-deprived individuals show reduced prefrontal control over food choices (impulsivity increases). The metabolic cost of being awake is insufficient to offset these overconsumption effects.
Can losing weight improve sleep?
Yes, particularly for obese individuals with obstructive sleep apnea (OSA), where excess tissue around the throat collapses the airway during sleep. Weight loss of 10–15% significantly reduces apnea severity (AHI). Even in people without OSA, improved metabolic health from weight loss may improve sleep architecture. The relationship is bidirectional: better sleep also makes weight management easier.