Sleeping the Pounds Away By: Kelly Skretta, Dietetic Intern

Sleep is often the first thing we sacrifice when days get busy. A good night’s sleep is particularly hard to fit in when we’re trying to prepare healthy meals and squeeze in the proper amount of physical activity each day. But recent studies show that enough sleep might help us in other ways than just staying refreshed, making it worth our time to consider our sleeping habits. Scientists have recently linked the amount of sleep people get to hormone levels in the body. Specifically, sleep is associated with levels of ghrelin and leptin hormones1. Ghrelin lets us know when we’re hungry; its counterpart, leptin, tells us when we’re full. This communication system works best when hormone levels are appropriate and in correct proportion in the body. Research has shown that short sleep duration (generally less than seven hours a night) causes an imbalance in these hormone levels, which causes our bodies to receive inaccurate messages. For example, when ghrelin levels are high and leptin levels are low, we might have insatiable appetites despite having plenty to eat or drink. In turn, this can cause our daily caloric intake to increase and lead to weight gain over time. An important study conducted by Taheri et. al in 2004 linked short sleep duration (less than eight hours) to reduced leptin, elevated ghrelin, and increased body mass index (BMI) among its subjects2. This prompted similar studies conducted across different population groups, age groups, and countries3-7. The results are consistent, making a convincing link between shorter sleep duration and obesity. The specifics of how this occurs in the body are still being researched, however, as well as potentially significant trends related to specific food cravings and choices that come with increased appetite. Besides the connection between short sleep duration and increased weight, getting inadequate sleep has been noted as a risk factor for hypertension and insulin sensitivity. Bjorvatn et. al studied the association between sleep duration and metabolic measures and concluded that in addition to increased BMI and elevated lipid panel measures, patients with short sleep duration had elevated systolic and diastolic blood pressures8. Spiegal et. al reviewed the research covering sleep duration and insulin resistance risk, and concluded that many studies showed glucose metabolism (the regulation of glucose in the blood) changed in adult subjects with restricted sleeping9. They also reaffirmed studies that showed sleep loss alters hormone regulation, leading to increased appetite. Therefore, they concluded that chronic sleep loss may be a risk factor for insulin resistance, type-2 diabetes and weight gain. The connection between sleep duration, weight, and other metabolic disorders being analyzed in current research provides a promising insight into a potential prevention and treatment method of obesity. We’ve determined short sleep duration to be detrimental to our health, so how much sleep is enough to stay healthy? According to the National Heart Lung and Blood Institute’s Healthy Sleep Guide, sleep needs vary among individuals and lifestyles10. On average, adults need at least seven hours of

sleep a night, with many adults needing nine or more hours. By contrast, children need between ten and twelve hours each night and adolescents need at least nine hours a night. These recommendations may seem extreme if we’re accustomed to getting five hours or less of sleep each night. With recent studies showing the risks of not getting enough sleep, though, we might just find the motivation to reschedule our days so we can prevent obesity and other disease risks. References 1

Kondracki, Nancy. 2008. Professional Dialogue: The Sleep / Weight Connection. RD411. http://www.rd411.com/

2

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. Public Library of Science, 1(3), e62.

6

3

Gangwisch, J. E., Malaspina, D., Boden-Albala, B., & Heymsfield, S. B. (2005). Inadequate sleep as a risk factor for obesity: Analyses of the NHANES I. Sleep, 28(10), 1289-1296.

4

Chaput, J. P., Despres, J. P., Bouchard, C., & Tremblay, A. (2007). Short sleep duration is associated with reduced leptin levels and increased adiposity: Results from the Quebec family study. Obesity, 15(1), 253-261.

5

Lumeng, J. C., Somashekar, D., Appugliese, D., Kaciroti, N., Corwyn, R. F., & Bradley, R. H. (2007). Shorter sleep duration is associated with increased risk for being overweight at ages 9 to 12 years. Pediatrics, 120(5), 1020-1029.

Park, Y. J., Lee, W. C., Yim, H. W., & Park, Y. M. (2007). The association between sleep and obesity in Korean adults. Journal of Preventive Medicine & Public Health / Yebang Uihakhoe Chi, 40(6), 454-460. 7

Rontoyanni, V. G., Baic, S., & Cooper, A. R. (2007). Association between nocturnal sleep duration, body fatness, and dietary intake in Greek women. Nutrition, 23(1112), 773-777.

8

Bjorvatn, B., Sagen, I. M., Oyane, N., Waage, S., Fetveit, A., Pallesen, S., et al. (2007). The association between sleep duration, body mass index and metabolic measures in the Hordaland health study. Journal of Sleep Research, 16(1), 66-76.

9

Spiegel, K., Knutson, K., Leproult, R., Tasali, E., & Van Cauter, E. (2005). Sleep loss: A novel risk factor for insulin resistance and type 2 diabetes. Journal of Applied Physiology, 99(5), 2008-2019.

10

U.S. Department of Health & Human Services. National Heart Lung & Blood Institute. 2006. Your Guide to Healthy Sleep, 13-21. http://www.nhlbi.nih.gov/health/public/sleep/healthy_sleep.pdf