Poor Sleep Tied to Worse Cognition in Youth Classified as Overweight, Obese

Adolescents who are classified overweight or obese vs those with a healthy weight have worse cognitive outcomes following poor sleep, according to study results published in JAMA Neurology.

Previous research suggests that sleep mediates some of the relationship between adiposity and cognitive function. As poor sleep and obesity are both common among adolescents, researchers of the current study decided to evaluate the effect adiposity has on sleep and cognitive function.

The researchers conducted a single-blind, randomized, crossover trial (ClinicalTrials.gov Identifier: NCT04346433) and recruited adolescents aged 14 to 19 between 2020 and 2022 in Birmingham, Alabama. The participants (N=61) and their caregivers completed a survey about demographic information, the Food Questionnaire, and Childhood Eating Behaviors Questionnaire and were instructed to sleep with an actigraphy for 9 hours or 4 hours in a random order with 2 normal nights of sleep in between. The morning after a sleep study night, the participants attended a laboratory visit the next morning and completed the National Institutes of Health Cognitive Toolbox and Stroop task inhibition assessments.

The effects of adequate and restricted sleep on cognitive outcomes were compared between adolescents classified as a healthy weight (n=31) and overweight or obese (n=30) status.

The healthy and overweight or obese groups comprised 16 (mean age, 16.1; Black, 41.9%; weekday sleep duration, 7 hr 6 mins; sleep typical weekday time, 23:39:47) and 19 (mean age, 16.6; Black, 63.30%; weekday sleep duration, 7 hr 26 mins; sleep typical weekday time, 23:35:09) girls.

In general, the researchers found worse scores in adolescents who were overweight or obese vs adolescents who were a healthy weight for the outcomes of cognitive flexibility (mean difference [MD], 12.52; P =.01), fluid cognition (MD, 9.9; P =.03), and attention (MD, 8.32; P =.01).

A significant interaction between BMI and sleep condition was observed on cognitive flexibility (F_[1,56], 10.94; P =.002), fluid cognition (F_[1,56], 8.54; P =.005), global cognition (F_[1,56], 6.49; P =.01), and attention (F_[1,56], 5.50; P =.02) outcomes.

Following sleep restriction, adolescents who were overweight or obese vs those who were a healthy weight had worse cognitive flexibility (MD, 8.00; P<.001), fluid cognition (MD, 7.49; P <.001), and global cognition (MD, 5.18; P=.003) scores.

A moderation analysis found that 1 night of poor sleep associated with worse processing speed (F_[1,58], 7.49; P =.008) and fluid cognition (F_[1,57], 5.50; P =.02) for the adolescent with a total body fat percentage (TBF%) greater than 42% and with worse cognitive flexibility (F_[1,59], 4.74; P =.03) for those with a TBF% greater than 55%.

The order that the participants completed the sleep conditions affected global cognition, fluid cognition, working memory, and processing speed outcomes (all P ≤.02).

This study may have been limited by using an at-home sleep intervention, which introduced variability in sleep duration and environment.

“Future research should identify novel pathways through which to support adolescents with overweight or obesity, promote improved health outcomes, and investigate the role of other behavioral and biological (ie, dim light melatonin onset) factors within these relationships,” the researchers concluded.