National Sleep Foundation

Chapter 1: Normal Sleep

The Physiology of Sleep – Obesity & Weight

Lack of sleep is associated with an increased risk of obesity: the shorter length of time a person sleeps, the greater their risk of being obese, based on the Body Mass Index (BMI).

Adults who sleep less than 7.7 hours a night are more likely to have a high BMI. One longitudinal study of 500 adults found that, by age 27, those who slept less than 6 hours per night were 7.5 times more likely to have a higher BMI (the researchers controlled for family history, physical activity, and demographic factors)73.

This association seems to be caused by a lack of sleep decreasing a person’s levels of leptin (a hormone that suppresses appetite), and increasing levels of ghrelin (a peptide that stimulates appetite). These are influenced by orexin and may be altered by changes in sleep and circadian processes. Hence, lack of sleep appears to result in lower leptin and higher ghrelin levels, both of which make you eat more and gain weight.73

Obesity is also a risk factor for obstructive sleep apnea (OSA) in middle-aged adults, perhaps because one’s airways become more fleshy and narrower as one gains weight74. (OSA also occurs in individuals who are not overweight, and is more common as we age75.) Obesity can lead to OSA, and it can result from OSA. The two conditions reinforce and compound each other: obesity can lead to OSA, which results in excessive sleepiness and fatigue, which inhibits the person from exercising, which further contributes to obesity.

References

72. Institute of Medicine (IOM) Committee on Sleep Medicine and Research, Colten HR and Altevogt BM (ed.), Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem, Washington, DC:

73. Institute of Medicine (IOM) Committee on Sleep Medicine and Research, Colten HR and Altevogt BM (ed.), Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem, Washington, DC: National Academy of Sciences, 2006.

74. Institute of Medicine (IOM) Committee on Sleep Medicine and Research, Colten HR and Altevogt BM (ed.), Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem, Washington, DC: National Academy of Sciences, 2006.

75. Endeshaw, Yohannes, “Clinical Characteristics of Obstructive Sleep Apnea in Community-Dwelling Older Adults,“ JAGS 2006: 54:1740-1744..