A healthy diet, regular exercise, and stress management — these are well-established factors that promote weight control. But emerging evidence suggests that sleep also plays a powerful role in obesity and related conditions, which is one reason the American Heart Association added sleep to its list of “life’s essentials,” and most recently published a scientific statement on sleep health and its implications for cardiometabolic health.
Getting insufficient sleep, in particular, has been associated with obesity in epidemiological studies for more than two decades. The connection was highlighted in an article several years ago that noted, “The detrimental effects of inadequate sleep on health and public safety drive an explosion of sleep research.” That research has confirmed the relationship between inadequate sleep and obesity, as well as a range of related disorders including diabetes, cardiovascular disease, and hypertension.
In addition, a recent cross-sectional study found a sleep duration of less than 7 hours increased the overweight and obesity rate nearly twofold compared with sleeping 7-9 hours, while a recent randomized controlled trial found that insufficient sleep predicted poor weight-loss maintenance with liraglutide.
“I strongly believe that getting enough sleep could help tackle our society’s obesity epidemic,” Esra Tasali, MD, director, UChicago Sleep Center, Chicago, told Medscape Medical News. “Remarkably more than one third of US adults are not getting enough sleep on a regular basis, which strongly increases their risk for chronic conditions,” including obesity.
How Does Poor Sleep Drive Obesity?
A strong link exists between sleep and obesity, and it seems to be a bidirectional association, Christopher E. Kline, PhD, coordinator, Exercise Physiology PhD program and faculty member of the Center for Sleep and Circadian Science at the University of Pittsburgh, Pittsburgh, told Medscape Medical News. “Poor sleep predisposes one to obesity and weight gain, while obesity promotes poor sleep.”
Poor sleep may cause obesity via several pathways, he explained. “Poor sleep could lead to altered substrate utilization — for instance, it’s well documented that poor sleep reduces insulin sensitivity.”
Appetite regulation is another possible pathway. “There’s some evidence (though not as compelling as initially thought) that poor sleep causes increases in ghrelin and decreases in leptin, two potent appetite-regulating hormones,” he said.
In addition, people with overweight/obesity and poor sleep often have a reduced inability to resist calorie-dense foods — findings showed in both feeding and brain imaging studies. For example, a study by Kline and colleagues showed that poor sleep leads to lower adherence to lifestyle modifications during attempted weight loss — specifically, lower adherence to caloric intake goals and physical activity.
Less physical activity means more sedentary behavior, “which results in reduced energy expenditure and, if caloric intake stays the same, altered energy balance,” Kline said.
Sleep disorders such as sleep apnea can also sabotage weight-loss efforts, he added. His group found that in the context of a 12-month behavioral weight-loss intervention focusing on dietary modification and physical activity, adults with sleep apnea lost less weight than those who didn’t have sleep apnea.
“Curtailed sleep also significantly slows resting metabolic rate and increases risk of sarcopenic obesity,” noted Janelle Wilder Coughlin, PhD, director of the Obesity Behavioral Medicine Program and associate director of the Center for Behavior and Health at the Johns Hopkins School of Medicine in Baltimore.
“Furthermore,” she told Medscape Medical News, “studies conducted in experimental laboratories found that sleep restriction results in increased hunger, calorie consumption, snacking, and loss of control eating in comparison to individuals with normal sleep.”
Does Improving Sleep Improve Weight Loss?
Right now, there is little evidence to show that improving sleep will boost weight loss, according to Kline. For example, studies that treat patients with sleep apnea with continuous positive airway pressure have not shown better weight loss.
Nevertheless, emerging evidence suggests that some interventions might be helpful. For example, Tasali led a single-center randomized controlled study on the effect of sleep extension on energy intake among adults with overweight. Participants were randomly assigned to an individualized sleep hygiene counseling session that aimed to extend their bedtime to about 8.5 hours or to continuation of habitual sleep pattern. They did not change their diet or physical activity regimen.
The intervention increased sleep duration by approximately 1.2 hours per night, and the sleep-extension group had a significant decrease (-270 calories) in energy intake and weight reduction compared with the control group, with no effect on energy expenditure.
More recent research suggests that additional dimensions of sleep — beyond insufficient time — can interfere with weight loss, Kline said. In an analysis of data from adults participating in a year-long behavioral weight-loss intervention, “we documented that individuals with poor ‘sleep health’ — eg, those with significant variability in their sleep, poor satisfaction, late timing, and/or low efficiency — lost less weight.”
Coughlin added, “Several studies have shown that poor baseline sleep predicts a less favorable response to weight-loss treatment, including less fat mass loss and less weight-loss maintenance. While randomized trials are limited,” she told Medscape Medical News, “these data suggest that addressing patients’ sleep disturbances before or during a weight-loss attempt may be important.”
How to Help Patients Sleep Better
While research continues to emerge, clinicians can take steps now to help their patients sleep better, the experts agreed. “The general ‘sleep hygiene’ tips are a great start,” Kline said. “This includes keeping a consistent sleep schedule, keeping the bedroom dark and cool, having a wind-down routine in the evening leading to bed, prioritizing light exposure during the day (especially upon awakening) and minimizing light exposure in the hours leading to bedtime, and exercising and being active during the day.”
“More than anything, though, individuals need to prioritize getting sufficient sleep on a nightly basis and should not rely on daytime naps or sleeping in on the weekend,” he cautioned. “While those can help minimize sleep loss, it’s ideal to get sufficient sleep on a consistent basis.”
Tasali noted that blue light exposure from electronic devices can reduce the hormone melatonin, which helps to initiate and maintain sleep, so electronics use should be limited close to bedtime. This means avoiding excessive use of social media, phone scrolling, texting, gaming, and binge-watching shows on television.
In contrast, a good sleep routine — including a warm bath, reading, or listening to soft music — can be helpful, she said.
While getting up in the middle of the night to eat should be discouraged, “Waking up hungry may drive early-day overeating, often with high-calorie, low-nutrient foods, reinforcing metabolic dysfunction and weight gain,” said Peter Goulden, MD, chief, Division of Endocrinology, Diabetes and Bone Diseases, at Mount Sinai Morningside and Mount Sinai West in New York City. “It may also reflect poor sleep quality, which is independently associated with cardiometabolic risk.”
“Look for signs of nocturnal eating or nighttime hypoglycemia in patients with diabetes,” he told Medscape Medical News. “Also, assess for mood or stress-related eating patterns, which often manifest during the night or early morning hours.”
Tasali pointed out that despite the growing interest in the positive effects of weight-loss medications, “there is still a lot of uncertainty about their long-term biological effects and how they will ultimately change people’s eating habits and lifestyle behaviors. We also know that when you stop these drugs, you rapidly regain weight.”
In light of this, she said, “clinicians should consider ‘adequate sleep’ as a third pillar of healthy lifestyle behavior alongside diet and exercise for healthy weight maintenance and prevention of weight gain. Healthier sleep can help people eat healthier food — among many other benefits to overall health and well-being — and therefore help reduce weight gain and other cardio-metabolic conditions.”
Kline added, “It’s important to ask patients about their sleep — especially if the clinician wants the patient to alter their lifestyle habits. For some individuals, poor sleep could be an important factor that gets in the way of attempted behavior modification!”
Kline, Coughlin, Tasali, and Goulden reported no conflicts of interest.
Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.