In my blog yesterday I mentioned how a carbohydrate-rich diet can drive some people to overeat. High-carb foods tend to disrupt blood sugar levels in a way that can lead to episodes of low blood sugar that itself can trigger cravings for further carb-rich fare. Also, carbohydrate has relatively limited capacity to sate the appetite compared to, say, protein. Try as some people might, they can find it virtually impossible to control their food intake if their diet is stuffed full of carbohydrates rich in sugar and/or starch.
Appetite is something that is at least partly under the control of hormones including ghrelin (which stimulates appetite) and leptin (which suppresses appetite). There secretion of these hormones is a complex affair, no doubt, but one thing we know can influence this is sleep. Research has found that sleep restriction has the capacity to stimulate ghrelin secretion and/or suppress leptin secretion. In other words, sleep restriction has the capacity to alter hormones in a way that can stimulate appetite. That’s not good if someone is struggling to eat enough food, but not too much.
Back in May one of my blog posts focused on a piece of research which restricted sleep in study participants, and found that this led to an increase in the amount they ate. Unlike other studies, this found no significant change in the levels of ghrelin or leptin. Nevertheless, the increase in eating was significant.
Yesterday, another relevant study appeared in the American Journal of Clinical Nutrition . In it, young men were given access to set foods after being allowed to sleep for about 8 hours (normal sleep) on one occasion, and 4 hours (sleep restriction) on another. In reality, individuals slept for an average of about 3 hrs 45 mins and 7 hours 15 mins respectively. Hormone levels were not monitored, but food intake was.
After the night of sleep restriction, caloric intake was an average of about 560 calories (22 per cent) higher.
This was a small study and only tested the effect of one night of quite extreme sleep deprivation. However, it is possible that milder forms of sleep deprivation in the long term may also stimulate appetite in a way that could encourage overeating. As this study points out, several studies have found a link between shorter sleep time and higher body mass index in Spain , France , Japan  and the USA [5-7].
1. Brondel L, et al. Acute partial sleep deprivations increases food intake in healthy men. Am J Clin Nutri 31 March 2010 [epub ahead of print].
2. Vioque J, et al. Time spent watching, sleep duration and obesity in adults living in Valencia, Spain. Int J Obes Relat Metab Disord 2000;24:1683-8
3. Cournot M, et al. Environmental factors associated with body mass index in a population of Southern France. Eur J Cardiovasc prev Rehabil 2004;11:291-7
4. Shigeta H, et al. Lifestyle, obesity and insulin resistance. Diabetes Care 2001:24;608
5. Vorona RD, et al. Overweight and obese patients in a primary care population report less sleep than patients with normal body mass index. Arch Int Med 2005;165:25-30
6. Singh M, et al. The association between obesity and short sleep duration: a population-based study. J Clin Sleep Med 2005;1:357-63
7. Gangwisch JE, et al. Inadequate sleep is a risk factor for obesity: analyses of the NHANES 1. Sleep 2005;28:1289-96
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