woman yawning contagious
A lack of sleep tends to make people consume excess calories. istock

Sleep deprivation has a significant effect in increasing appetite, research published in the European Journal of Clinical Nutrition has found. A bad night's sleep also makes people tend to choose different foods, seeking out high-fat and high-protein foods.

Gerda Pot, a nutrition scientist at King's College London in the UK and Vrije Universiteit Amsterdam in the Netherlands and author of the study, analysed 11 studies with a total of 172 participants to see how they ate after short-term sleep deprivation.

She found that people ate significantly more after a restricted length of sleep: 385 calories more, or the equivalent of about four and a half slices of bread.

Unfortunately, study participants didn't burn any more energy after sleep deprivation than people who had had a good night's sleep. The extra energy that they consumed after little sleep would contribute to weight gain, the research suggests.

"Not having enough sleep has a big impact on your biological clock and therefore your metabolism," Pot told IBTimes UK. "I'm really interested in the timing of eating – what people eat and when people eat. That brought me into working to the biological clock, which is closely related to sleep. It seems that if people don't have enough sleep it has a big effect on their diet."

People seek out high-fat and high-protein foods after little sleep. Pan Pacific / Flickr

"Our results highlight sleep as a potential third factor, in addition to diet and exercise, to target weight gain more effectively," says Haya Al Khatib, lead author of the study and a PhD student at King's College London.

The next step in this research is to do a randomised controlled trial in people who habitually sleep very little, to see whether there is a relationship between little sleep and weight gain. Pot and her colleagues are also going to look into whether the increased appetite after sleep deprivation has a hormonal or primarily neurological basis.

The National Sleep Foundation recommends about seven to nine hours' sleep a night for adults, and say that less than six hours a night may compromise health and well-being.