Insufficient sleep can reduce mood, cause mood swings, reduce cognitive function, increase risk of numerous diseases and even increase mortality rate in certain populations. But, as is the case with typical illogical human thought, most deny mood swings, care little about cognitive function and see death or disease as something to worry about as and when it happens… When it comes to weight gain however, everyone seems to sit up and pay attention. So sit up, and pay attention!

The worldwide obesity epidemic is worsening, the media is focusing and individuals are becoming increasingly aware that something is wrong. Poor lifestyle choices, increasingly sedentary jobs, technological advancement and consumption of poor quality, easily accessible foods are all arguably to blame. Whilst these are all problems for the most, for certain subsets of our population, the increased energy intake and reduced expenditure associated with weight gain may well be attributed to other factors. It appears that those busy individuals restricting sleep may well be doing their appetite a disservice.

To clarify, long term weight gain is caused by consuming more energy (calories) than is burned. Ultimately an individual gaining weight is one that is eating more than their body needs to maintain its internal environment, complete bodily processes and engage in required physical activity. In order to reduce an energy surplus (consuming more than burning) an individual can look to eat less, or move more. In a healthy adult maintaining their weight, appetite (hunger) usually regulates energy consume to ensure maintenance of body mass.

Sleep deprivation has numerous implications on the energy balance. Individuals in a sleep deprived state are more likely to buy high calorie foods (Chapman et al, 2013) even after controlling for financial expenditure. In accordance with an increased desire for food even short term sleep deprivation of as little as four hours below baseline may increase energy intake (Brondel et al, 2010). Increased hunger is thought to be caused by depressed leptin and increased ghrelin levels (hormones controlling appetite), this is evident in sleep deprived individuals who experience greater hunger levels than those getting recommended sleep duration (Taheri et al, 2004; Schmid et al, 2008). This contributes to an energy surplus leading to weight gain. (Markwald et al, 2013).

So what does all this mean? Well based upon an initial analysis of current literature sleep deprivation makes people hungrier, eat more and gain weight. In fact one may argue that increasing pressure on individuals to restrict sleep may contribute to the increasing prevalence of obesity worldwide, although there are certainly more influential factors present.

In terms of recommendations it seems below six hours seems to have the most profound effect, similar to other implications noted on performance and cognitive function. Therefore sticking to recommended guidelines of between 7 and 8 high quality hours of sleep per night seems adequate. However obviously these recommendations will differ between individuals.

Jack Barton (Researcher, Rescon Ltd)

References
Brondel, L., Romer, M. A., Nougues, P. M., Touyarou, P., & Davenne, D. (2010). Acute partial sleep deprivation increases food intake in healthy men.The American Journal of Clinical Nutrition, 91(6), 1550-1559.
Chapman, C. D., Nilsson, E. K., Nilsson, V. C., Cedernaes, J., Rångtell, F. H., et al. (2013). Acute sleep deprivation increases food purchasing in men. Obesity, 21(12), E555-E560.
Markwald, R. R., Melanson, E. L., Smith, M. R., Higgins, J., Perreault, L., et al. (2013). Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain. Proceedings of the National Academy of Sciences, 110(14), 5695-5700.
Schmid, S. M., Hallschmid, M., Jauch‐Chara, K., Born, J., & Schultes, B. (2008). A single night of sleep deprivation increases ghrelin levels and feelings of hunger in normal‐weight healthy men. Journal of Sleep Research,17(3), 331-334.
Taheri, S., Lin, L., Austin, D., Young, T., & Mignot, E. (2004). Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index. PLoS Medicine, 1(3), e62.