Short or Long Sleep Duration Linked to Weight Gain 

Patients who slept for short or long durations experienced an increase in weight compared with those who slept for an average duration of 7 to 9 hours, according to the results of a longitudinal study.

"Individual and environmental factors that have an influence on energy balance are not fully understood," write Jean-Philippe Chaput, MSc, from Laval University in Quebec City, Quebec, Canada, and colleagues. "Current treatments for obesity have been largely unsuccessful in maintaining long-term weight loss, suggesting the need for new insight into the mechanisms that result in altered metabolism and behavior and may lead to obesity."

To determine the relationship between sleep duration and subsequent body weight and fat gain, the investigators evaluated body composition measurements and self-reported sleep duration in 276 adults aged 21 to 64 years who were enrolled in the Quebec Family Study, a 6-year longitudinal study in a community setting. More than half of the sample was drawn from families in which at least 1 parent and 1 offspring had a body mass index (BMI) of 32 kg/m2 or higher. The investigators compared changes in adiposity indices among groups determined by sleep duration: short (5 – 6 hours), average (7 – 8 hours), and long (9 – 10 hours).

Compared with average-duration sleepers, short-duration sleepers gained 1.98 kg more in a 6-year period (95% confidence interval [CI], 1.16 – 2.82), and long-duration sleepers gained 1.58 kg more (95% CI, 1.02 – 2.56) after adjustment for age, sex, and baseline BMI. At 6 years, short-duration and long-duration sleepers were 35% and 25% more likely to experience a 5-kg weight gain, respectively, vs average-duration sleepers.

Compared with average-duration sleepers, short-duration sleepers had a 27% increased risk for the development of obesity, and long-duration sleepers had a 21% increase in risk. Adjustment for energy intake and physical activity participation did not affect these associations, which remained significant after inclusion of important covariates.

"This study provides evidence that both short and long sleeping times predict an increased risk of future body weight and fat gain in adults," the study authors write. "Hence, these results emphasize the need to add sleep duration to the panel of determinants that contribute to weight gain and obesity."
Practice Pearls:

• After adjustment for age, sex, and baseline BMI in a 6-year period, short-duration sleepers gained 88% more weight vs average-duration sleepers, on average, and increase in waist circumference and percentage of body fat was 58% and 124% higher, respectively. During 6 years, short-duration sleepers were 35% more likely to experience a 5-kg weight gain vs average-duration sleepers, and they had a 27% increased risk for obesity.
• After adjustment, long-duration sleepers also had a significantly higher increase in body weight (71%), waist circumference (47%), and percentage of body fat (94%) vs the increase seen in average-duration sleepers. During 6 years, long-duration sleepers were 25% more likely to experience a 5-kg weight gain vs average-duration sleepers, and they had a 21% increase in the risk for the development of obesity.

Sleep. 2008;31:517-523.