Anyone who has reached for something sugary after a bad night’s sleep has felt this connection firsthand. It turns out there’s a fairly well-studied hormonal reason behind it.
The hunger-hormone link
Sleep researchers have repeatedly found that short sleep duration is associated with higher levels of ghrelin, a hormone that stimulates appetite, and lower levels of leptin, a hormone that signals fullness. In controlled sleep-restriction studies, participants who slept around four to five hours a night reported measurably higher hunger and stronger cravings for high-calorie, high-carbohydrate foods the next day compared with participants who slept seven to nine hours.
Energy, not just appetite
Poor sleep also affects insulin sensitivity. Some studies have found that even a single night of restricted sleep can temporarily reduce how efficiently the body clears glucose from the bloodstream. Over time, chronic short sleep has been associated in observational research with a higher risk of metabolic issues, though this research shows association, not that poor sleep alone causes those outcomes for any given individual.
Habits that support better sleep
- Keep a consistent sleep and wake time, including weekends.
- Limit bright light and screens in the hour before bed.
- Avoid large meals, alcohol, and caffeine close to bedtime.
- Keep the bedroom cool, dark, and quiet.
- Get daylight exposure earlier in the day, which supports the sleep-wake cycle at night.
Sleep needs vary by individual, and persistent sleep problems — trouble falling asleep, frequent waking, snoring, or ongoing daytime fatigue — are worth discussing with a healthcare provider, since they can have underlying causes (like sleep apnea) that home habits alone won’t fix.