Chronically Short Sleep May Lead to Weight Gain in Adults With Heart Risks

Key Takeaways - For adults with elevated cardiometabolic risk who usually slept for at least 7 hours per night, body weight increased by 1 lb over 6 weeks when they lost 1.5 hours of sleep each night, an analysis of two trials showed. - Sleep reduction also increased sedentary time (difference of 17.2 minutes per day) after adjustment for time spent in bed. - These findings expand the evidence for a causal link between sleep and weight, and also support discussing sleep duration with patients to help weight management and obesity prevention across the lifespan. Shorter periods of sleep over the long term may lead to weight gain in adults at increased risk for cardiometabolic disease, a pooled analysis of two randomized trials suggested. For adults with elevated cardiometabolic risk who usually slept for at least 7 hours per night, body weight increased by 0.45 kg (1 lb; 95% CI 0.33-0.57) over 6 weeks when they lost 1.5 hours of sleep each night, while waist circumference and whole-body volume increased by 0.52 cm (95% CI 0.25-0.79) and 0.56 L (95% CI 0.19-0.93), respectively. "The magnitude of change mirrors population trends in annual weight gain during early and middle adulthood and may contribute to increased risk for obesity and cardiometabolic disorders over time," wrote Marie-Pierre St-Onge, PhD, of Columbia University Irving Medical Center in New York City, and colleagues in the Annals of Internal Medicine. Sleep reduction also increased sedentary time (difference of 17.2 minutes per day, 95% CI 11.7-22.7) after adjustment for time spent in bed. "If replicated, this finding can have important clinical relevance, as greater time spent sedentary may contribute to adiposity gains and predicts elevated risk for cardiometabolic diseases and mortality," the researchers noted. These findings expand the evidence for a causal link between sleep and obesity, with prior research showing a positive energy balance from more severe sleep restriction over short periods in inpatient experiments. The sleep restriction studied here is a "real-world" version of sleep loss, as 78% of adults that report sleeping less than 7 hours a night get 6 hours of sleep, St-Onge and team explained. "These findings highlight the importance of discussing sleep duration at healthcare encounters and support guidance to maintain adequate sleep duration to improve weight management and obesity prevention across the lifespan," they concluded. The two randomized crossover trials included a total of 95 adults ages 20 and older who habitually slept 7 or more hours per night (confirmed by wrist actigraphy). They were randomized to either maintain their usual bed and wake times for a total of at least 7 hours of sleep or to reduce their nightly sleep by about 1.5 hours by delaying their bedtime for 6 weeks. After a multi-week washout period, participants crossed over to the other study arm. One trial included women and was primarily focused on cardiometabolic risk factors; the other recruited both men and women and primarily focused on measures of energy balance regulation. Adherence monitored by wrist actigraphy and nightly sleep diaries showed that sleep duration differed by 78.4 minutes between groups, with a similar magnitude of difference in the two arms between trials. Mechanistic analysis showed elevated leptin levels -- a marker of energy stores -- with sleep reduction (difference of 2.03 ng/mL, 95% CI 0.38-3.68). "Although a topic of debate, one potential explanation for this effect [increased energy intake with less sleep] is dysregulation of hormonal control of appetite," St-Onge and team noted. They didn't find differences in ghrelin or GLP-1 levels between groups. The small sample size despite pooling across two trials limited the generalizability of the findings, as well as the ability to formally test treatment effect differences by gender and menopausal status, according to the researchers. The study also measured metabolic characteristics only in a morning fasted state, precluding observations about metabolites known to fluctuate with circadian rhythmicity, like ghrelin. "In addition, although this study reflects a long intervention period for the field, the 6-week duration of [sleep restriction] may have been too short to observe substantial changes in body tissue distribution," St-Onge and colleagues wrote.