Not getting enough sleep may impact people’s weight loss goals, stopping them from keeping the weight off once it is lost, new research suggests.
A study performed at the University of Copenhagen has found that not getting enough sleep can hinder attempts to maintain weight loss after dieting, discovering that two hours of vigorous exercise per week can help sustain a better quality sleep schedule.
Adrian F. Bogh, a medical student at the University of Copenhagen, commented: “It was surprising to see how losing weight in adults with obesity improved sleep duration and quality in such a short time, and how exercising while attempting to keep the weight off preserved improvements in sleep quality. Also, it was intriguing that adults who aren’t sleeping enough or getting poor quality sleep after weight loss appear less successful at maintaining weight loss than those with sufficient sleep.”
Impacts of not getting enough sleep
Research shows that over a third of adults in the UK and US are not getting enough sleep on a regular basis – between six and seven hours per night. A range of factors influences this, such as stress, computers and smartphone use, and poor work life balance.
Additionally, not getting enough sleep or only getting poor quality sleep can enhance the risk of high blood pressure, high cholesterol, and atherosclerosis. Poor sleep is also associated with diabetes, inflammation, and obesity, all of which exacerbate the cardiovascular disease. Previous research has found that getting too much or too little sleep can increase the risk of stroke, heart attack and death, and poor sleep habits also contribute to weight gain after weight loss.
Understanding sleep and weight loss
To analyse the relationship between poor sleep duration and quality and weight loss maintenance, the team utilised data from the S-LiTE randomised placebo-controlled trial. The trial included 195 adults aged between 18 and 65 with obesity, defined as a body mass index (BMI) of 32 to 43 kg/m2. The participants followed a very low-calorie diet of 800 calories per day for eight weeks, losing an average of 12% of their body weight.
The team randomly assigned the individuals to four strategies for one year of weight loss maintenance. 49 of the participants had a daily injection placebo, 49 had a 3mg injection of the weight-loss drug liraglutide daily, 48 performed four exercise sessions per week, and 49 had a combination of both treatments. People in the exercise group were encouraged to participate in two supervised 45-minute exercise sessions per week consisting of spinning and circuit training and an additional two unsupervised session of 30 minutes.
The team analysed sleep duration using data from accelerometers that the participants wore before and after the low-calorie diet and after weeks 13, 26, and 52 of weight loss maintenance. The team used a self-rated questionnaire called the Pittsburgh Sleep Quality Index (PSQI) to measure sleep quality subjectively. Low scores indicate a better quality of sleep, with 0 representing optimal sleep and 21 the worst possible sleep – a score over five is considered poor quality sleep.
The association between sleep and weight gain was quantified by grouping the participants according to their average sleep duration (below/above six hrs/night) or sleep quality (below/above a PSQI score of five) after the low-calorie diet.
The team identified that sleep quality and duration improved in all of the participants following the eight-week low-calorie diet. After one year of weight maintenance, the exercise group maintained self-report improvements in sleep quality from the diet, whereas the groups that did not exercise relapsed and were now not getting enough sleep. The group receiving the weight-loss drug had no significant change in sleep quality or duration compared to the placebo group.
The analysis also demonstrated that those who were not getting enough sleep at the start of the study – averaging under six hours per night – increased their BMI by 1.3 kg/m2 during the year of weight maintenance compared to the good sleepers. Moreover, the poor sleepers at the start of the study, with a PSQI score of five or higher – increased their BMI by 1.2 kg/m2 during the weight maintenance phase compared to good sleepers with a PSQI score of less than five.
Professor Signe S. Torekov of the University of Copenhagen concluded: “The fact that sleep health was so strongly related to weight loss maintenance is important since many of us don’t get the recommended amount of sleep needed for optimal health and functioning. Future research examining possible ways of improving sleep in adults with obesity will be an important next step to limiting weight regain. Weight loss maintained with exercise seems promising in improving sleep.”
The researchers explained that due to the study being observational, they could not ensure that poor sleep contributes to weight changes but said it is likely to contribute.