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Obesity is often thought of as a disorder affecting those who overeat and under exercise, and yet even with optimal diets and workout routines, many still struggle to lose the extra weight. This suggests that there are other causes contributing to the increase in metabolic disorders that have continued to increase in prevalence in the last few decades. One such factor may actually be something we do every day without much thought: sleep.

Even though sleep is essential for optimal health and current guidelines recommend 7-9 hours of sleep a night, about one third of the US population is not getting the recommended amount of sleep. This means millions of people are at risk for adverse health consequences such as heart disease, high blood pressure, mental health disorders and diabetes.

“…shorter duration of sleep [is] associated with an increased risk for obesity”

Recent evidence has also suggested a link between sleep and obesity, with shorter duration of sleep associated with an increased risk for obesity. A February 2022 study in JAMA Internal Medicine aimed to discover if extending sleep duration could mitigate the risk for developing obesity, and the results were astonishing.

The study, titled “Effect of Sleep Extension on Objectively Assessed Energy IntakeAmong Adults With Overweight in Real-life Settings” consisted of a randomized clinical trial with 80 participants (49% women) ranging from 21-40 years of age. All participants were classified as being overweight based on BMI and typically slept for less than 6.5 hours a night based on self-report.

Researchers randomly assigned these participants to either a sleep extension group or a control group. The sleep extension group was given individualized sleep hygiene counseling sessions that were intended to extend their bedtime to 8.5 hours while the control group was instructed to continue their habitual sleep. In order to minimize the impact of other factors, participants were instructed to continue daily routine activities at home without any changes in diet or physical activity.

“the sleep extension group showed a significant decrease in energy intake compared with the control group from an added 1.2 hours of sleep per night”

After two weeks, participants in the sleep extension group showed a significant reduction of energy intake, by approximately 270 kcal, compared with the control group from an added 1.2 hours of sleep per night on average. In short, sleeping for a longer period of time each night decreased an individual’s energy intake, or number of calories consumed, the following day.

Additionally, energy expenditure did not change, resulting in a negative energy balance. Consequently, a modest reduction in weight after sleep extension was observed. If these findings can be replicated in more long-term studies, one could hypothesize an approximate 26 lb weight loss over 3 years without any other changes to diet or exercise habits.

“More energy […] may motivate someone to exercise more frequently and stay active throughout the day”

Participants in the sleep extension group also reported more daytime energy and alertness as well as better overall mood. These benefits on their own are notable for their potential to improve general wellbeing, and they may impact future behaviors in a positive manner as well. More energy, for instance, may motivate someone to exercise more frequently and stay active throughout the day. Additionally, better mood may lead someone to choose healthier meal options since low mood is associated with unhealthier food choices, which can in turn lead to multiple healthier lifestyle decisions as a domino effect.

The study concludes that “improving and maintaining healthy sleep duration over longer periods could be part of obesity prevention and weight loss programs,” adding to evidence that diet and exercise are not the only factors that influence obesity. Further research is needed, however, for a better understanding of how lengthening sleep duration would impact energy balance long term as well as the likelihood of maintaining these new sleep habits long term.

“…prioritizing 7-9 hours of sleep each night should be commonplace among all populations regardless of weight and risk factors.”

As increasing obesity rates continue to be a major component of the current chronic disease epidemic, public health education must take a more holistic approach to handling and mitigating this epidemic as current methods have seemingly been ineffective. Sleep should be considered as an intervention for prevention and treatment of obesity given that it is a no-cost option that has no negative side effects unlike weight loss medications and surgical interventions. And because the benefits of sleep go far beyond the treatment of obesity, prioritizing 7-9 hours of sleep each night should be commonplace among all populations regardless of weight and risk factors.