Sleep restriction promotes weight gain in high-risk adults 

1. In this pooled analysis of randomized crossover trials, chronic mild sleep restriction was associated with modest increases in body weight, waist circumference, and whole-body volume.

2. Although sleep restriction increased sedentary time, it did not alter time spent engaging in moderate-to-vigorous physical activity (MVPA) or total daily energy expenditure.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Insufficient sleep is consistently associated with an increased risk of obesity and poorer weight loss outcomes. However, most research examining the relationship between sleep and obesity has focused on severe sleep restriction (4–5 hours per night) over short durations (2 weeks or less), rather than the more common pattern of chronic mild sleep restriction (approximately 6 hours per night). This study aimed to evaluate the effects of “real-world” chronic short sleep on body weight regulation in adults. Participants completed two 6-week intervention periods in a randomized crossover design: one in which they delayed bedtime by 1.5 hours each night, resulting in chronic sleep restriction, and another in which they maintained at least 7 hours of sleep per night. Compared with adequate sleep, chronic sleep restriction was associated with increases in body weight, waist circumference, and whole-body volume. Participants also spent more time engaging in sedentary behaviour during the sleep-restricted period, although time spent performing moderate-to-vigorous physical activity (MVPA) remained similar between the two conditions. Several limitations should be considered when interpreting these findings, including the small sample size, relatively short intervention duration, limited statistical power to detect differences by sex and menopausal status, and modest effect sizes. Despite these limitations, the study provides valuable evidence that even modest, chronic sleep restriction may contribute to weight gain and adverse changes in body composition. These findings reinforce the importance of obtaining sufficient sleep as part of a comprehensive approach to weight management and the prevention of cardiometabolic disease.

Click to read this study in AIM

Relevant Reading: Short sleep duration is associated with higher risk of central obesity in adults: A systematic review and meta-analysis of prospective cohort studies

In-Depth [randomized controlled trial]: This pooled analysis combined data from two randomized crossover trials conducted between 2016 and 2023 to examine the effects of chronic mild sleep restriction on body weight regulation. In both studies, participants completed two 6-week outpatient interventions in random order: a sleep restriction condition, in which bedtime was delayed by 1.5 hours each night, and an adequate sleep condition, during which participants maintained their habitual sleep duration of at least 7 hours per night. The intervention periods were separated by a 4- to 6-week washout period. Both trials enrolled adults aged 20 years or older from the New York City area. Trial 1 included women with a body mass index (BMI) of 18.5–34.9 kg/m², while Trial 2 enrolled both women and men with a BMI of 20-33.5 kg/m² who also had one parent with type 2 diabetes, hyperlipidemia, or cardiovascular disease. Participants with cardiovascular, metabolic, neurologic, psychiatric, or sleep disorders, recent weight change, medications affecting sleep or appetite, shift work, or other factors likely to influence sleep or metabolism were excluded. Following a 2-week screening period, only participants who slept at least 7 hours on at least 70% of nights were eligible. Overall, 95 participants were randomized, including 72 women (76%), 15 of whom were postmenopausal. Compared with adequate sleep, chronic sleep restriction was associated with a mean increase in body weight of 0.45 kg (95% confidence interval [CI], 0.33-0.57 kg), waist circumference of 0.52 cm (95% CI, 0.25-0.79 cm), and whole-body volume of 0.56 L (95% CI, 0.19-0.93 L). However, the percentage of whole-body volume composed of adipose or skeletal muscle tissue did not differ between conditions. Fasting leptin concentrations increased and circulating ghrelin concentrations decreased during sleep restriction, but neither difference reached statistical significance, while fasting glucagon-like peptide-1 (GLP-1) levels were unchanged. Sleep restriction significantly increased sedentary time but had no effect on MVPA or free-living total daily energy expenditure. Overall, sleeping 1.5 fewer hours per night for 6 weeks resulted in modest but measurable increases in body weight, waist circumference, and whole-body volume compared with adequate sleep.

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