Researchers from King’s College London found that people who slept less than 7-hours per night were prone to eat the equivalent of four extra slices of toast or 385 calories per day and were less active throughout the day than those who slept for longer.
Previous studies demonstrated how sleep deprivation affected certain areas of the brain that could trigger a feeling of reward when exposed to high fat, low protein food sources. This could lead to obesity, diabetes, and cardiovascular disease.
This new research included the combined results of 11 studies and a total of 172 participants and was published in the European Journal of Clinical Nutrition.
How does sleep deprivation affect appetite?
Body clock and natural sleep cycle disruptions affect the hormones known as ghrelin and leptin, which are responsible for regulating appetite and triggering a feeling of fullness after a meal.
Researchers compared the results of a partial sleep restriction intervention with an unrestricted sleep control and then measured the energy intake of the participants over 24 hours.
Control subjects spent 7 to 12 hours per night in bed and the sleep-restricted participants got 3.5 to 5.5 hours of sleep per night.
What were the results?
It was found that the participants who got the least sleep expended less energy in the day than those who got sufficient rest, which suggested that they spent their day sitting, lying on the sofa or eating snacks. 
The participants who got more than 8 hours of sleep per night were found to consume an average of 385 calories less than those who were sleep-deprived and were found to also expended more energy throughout the day, leading to better overall health.
Dr. Gerda Pot from the Vrije Universiteit in Amsterdam and King’s College London, said: “The main cause of obesity is an imbalance between calorie intake and expenditure and this study adds to accumulating evidence that sleep deprivation could contribute to this imbalance. If long-term sleep deprivation continues to result in an increased calorie intake of this magnitude, it may contribute to weight gain.”
Any other health risks?
Dr. Pot says that sleep-deprivation is one of the most common and potentially modifiable health risks and that chronic sleep loss is becoming more common in today’s society.
“There might be some truth in saying ‘early to bed, early to rise, makes a man healthy and wise’”, she said.
Researchers have called for further studies to be carried out over longer periods in real-life cases because the current evidence is based on short studies that were carried out in the laboratory.
“More research is needed to investigate the importance of long-term, partial sleep deprivation as a risk factor for obesity and whether sleep extension could play a role in obesity prevention,” they said.
So far, the results have proven that just one week of an average of less than 6-hours of sleep per night could change the way that more than 710 types of genes function. It leads to anxiety, exhaustion, impulsive behavior, weight gain, hypertension, anger, and a lower immunity.
Studies have also shown that sleep deprivation affects attention, performance, and long-term memory, which encourages substance abuse and mental health disorders.
Sources:
https://psycnet.apa.org/psycinfo/1997-07865-006
https://science.sciencemag.org/content/221/4606/182
https://europepmc.org/abstract/med/16459757
https://www.sciencedirect.com/science/article/pii/S1087079207000202
https://www.sciencedirect.com/science/article/pii/S1389945708700133
