Articles · Habits
Short nights, big appetite: how sleep shapes what you eat
Why a few short nights leave you hungrier, especially for sweet and starchy food, what the studies found, and simple ways to protect your sleep.
· 4 min read
You slept badly, and by eleven o'clock you're circling the biscuit tin. Coincidence? Probably not. Researchers have found that short sleep changes the hormones that steer appetite, and nudges us towards the foods we're trying to eat less of. How does that work, and what can you do about it?
Two hormones, out of balance
Appetite is steered partly by two hormones:
- Leptin, made by fat tissue, tells the brain that the body has enough energy stored.
- Ghrelin, made mostly in the stomach, makes you feel hungry.
In a well-known experiment, healthy young men slept four hours a night for two nights, then ten hours a night for two nights. After the short nights, their leptin was 18% lower, their ghrelin 28% higher, and they felt 24% hungrier. Their appetite for calorie-dense, starchy and sweet foods rose by a third or more.
That was a small study, but larger ones point the same way. A review of studies that cut people's sleep short found that they ate on average about 385 kcal more, while burning no more energy.
Think about it: Think of your last short night. What did you eat the next day that you wouldn't normally?
Why sweet and starchy?
A tired brain wants quick energy, and it's also worse at saying no. In a brain-scan study, after a night without sleep, activity fell in the frontal areas that weigh up food choices and rose in the amygdala, a more impulsive, reward-driven region, and people wanted high-calorie foods more. Long evenings awake also simply give more time to snack.
Noon – Rest from Work (after Millet), Vincent van Gogh, 1890, Musée d'Orsay, Paris. Two farm workers asleep in the hay at midday, sickles and shoes set aside. Van Gogh painted it in 1890, after a drawing by Millet. Their sleep was earned in the fields; ours is often lost to screens. Public domain · Wikimedia CommonsHow much sleep is enough?
Sleep experts advise adults to sleep at least seven hours a night regularly. Children and teenagers need more. Needs vary from person to person, but if you rely on an alarm, lie in for hours at weekends, or feel sleepy during the day, you're probably not getting enough.
Habits that help
- Keep regular times, even at weekends: the body clock likes routine.
- Get daylight in the morning, and dim the lights in the evening.
- Stop caffeine by early afternoon. It stays in the body for hours.
- Go easy on alcohol. It helps you fall asleep but makes sleep lighter and more broken later in the night.
- Don't go to bed very full or very hungry: a light snack is fine, a big late meal isn't.
- Put the phone out of reach, and keep the bedroom cool, dark and quiet.
Try this: If you're short on sleep, plan for it: keep fruit, yogurt or nuts handy for the next day, so that the snack you reach for is a good one.
Think about it: What's the one thing that most often keeps you up later than you meant to?
Quick quiz
Which hormone makes you feel hungry, and which tells your brain you have enough energy?
Ghrelin makes you hungry; leptin signals that the body has enough energy stored. Short sleep pushes ghrelin up and leptin down.
In a review of studies that cut sleep short, how much more did people eat?
About 385 kcal more on average, without burning more energy.
How many hours of sleep do experts advise for adults?
At least seven hours a night, regularly.
Sources
- Spiegel K, et al. Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Annals of Internal Medicine, 2004.
- Al Khatib HK, et al. The effects of partial sleep deprivation on energy balance: a systematic review and meta-analysis. European Journal of Clinical Nutrition, 2017.
- Greer SM, Goldstein AN, Walker MP. The impact of sleep deprivation on food desire in the human brain. Nature Communications, 2013.
- Watson NF, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep, 2015.
General information, not medical advice. If you have a health condition, are pregnant or take medication, ask a doctor or dietitian what is right for you.