Less physical activity and more varied and disrupted sleep is associated with a less favorable metabolic profile in adolescents

BackgroundSleep and physical activity are modifiable behaviors that play an important role in preventing overweight, obesity, and metabolic health problems. Studies of the association between concurrent objective measures of sleep, physical activity, and metabolic risk factors among adolescents are limited. ObjectiveThe aim of the study was to examine the association between metabolic risk factors and objectively measured school day physical activity and sleep duration, quality, onset, and variability in adolescents. Materials and MethodsWe measured one school week of free-living sleep and physical activity with wrist actigraphy in 252 adolescents (146 girls), aged 15.8{+/-}0.3 years. Metabolic risk factors included body mass index, waist circumference, total body and trunk fat percentage, resting blood pressure, and fasting glucose and insulin levels. Multiple linear regression adjusted for sex, parental education, and day length was used to assess associations between metabolic risk factors and sleep and activity parameters. ResultsOn average, participants went to bed at 00:22{+/-}0.88 hours and slept 6.2{+/-}0.7 hours/night, with 0.83{+/-}0.36 hours of awakenings/night. However, night-to-night variability in sleep duration (0.87{+/-}0.57 hours) and bedtime (0.79{+/-}0.58 hours) was considerable. Neither average sleep duration nor mean bedtime was associated with any metabolic risk factors. However, greater night-to-night variability in sleep duration was associated with higher total body ({beta}=1.9{+/-}0.9 %/h, p=0.03) and trunk fat percentage ({beta}=1.6{+/-}0.7 %/h, p=0.02), poorer sleep quality (more hours of awakening) was associated with higher systolic blood pressure ({beta}=4.9{+/-}2.2 mmHg/h, p=0.03), and less physical activity was associated with higher trunk fat percentage (p=0.04) and insulin levels (p=0.01). ConclusionGreater nightly variation in sleep, lower sleep quality, and less physical activity was associated with a less favorable metabolic profile in adolescents. These findings support the idea that, along with an adequate amount of sleep and physical activity, a regular sleep schedule is important to the metabolic health of adolescents.