Youth with higher adiposity may be more susceptible to cognitive effects of poor sleep

Key takeaways:

• After one night of restricted sleep, youth with greater adiposity had poorer cognition scores vs. those with lower adiposity.
• The findings highlight the importance of promoting healthy sleep, an expert said.

Insufficient sleep was tied to poorer cognition and attention in adolescents who were classified as having overweight or obesity based on their BMI compared with those with normal weight, according to a recent study in JAMA Neurology.

“Research has shown a relationship between weight status and cognitive function,” Lindsay M. Stager, MA, a PhD candidate at the University of Alabama at Birmingham and the lead study author, told Healio. “We wanted to better understand why that relationship exists and assess the impact of sleep within this relationship given the impact sleep has on both weight and cognitive function.”

Stager and colleagues conducted a single-blind, randomized, crossover trial from September 2020 to October 2022 to evaluate the relationship between poor sleep, cognitive function and adiposity using both BMI and total body fat percentage as measures.

The final analysis included 61 adolescents (mean age, 16 years; 57.4% girls) who were assigned to either a restricted sleep period of 4 hours or an adequate sleep period of 8 hours following a 2-day period of adequate sleep.

The researchers measured cognitive function with NIH Cognitive Toolbox composite scores, which reflected global and fluid cognition and subscales that assessed attention, cognitive flexibility and processing speed.

Following restricted sleep, compared with adolescents with healthy weight, those with overweight or obesity based on BMI had poorer mean:

• global cognition scores (103.2 vs. 98);
• fluid cognition scores (102 vs. 94.5);
• cognitive flexibility scores (92.8 vs. 84.8); and
• attention scores (88.4 vs. 80).

The effects on cognition were similar when total body fat percentage was used to measure adiposity, according to the researchers.

However, the total body fat percentage cutoffs that demonstrated significant differences in fluid cognition, cognitive flexibility and processing speed were higher than the pediatric cutoffs used for overweight and obesity, the researchers noted. As a result, the total body fat percentage analyses “highlight increased risk for sleep-related cognitive impairment only for adolescents with obesity or severe obesity compared to all adolescents with overweight or obesity,” they wrote.

Aaron D. Fobian, PhD, an associate professor of psychiatry and behavioral neurobiology at the University of Alabama at Birmingham and the study’s corresponding author, said it was interesting to find that just one night of sleep restriction impacted cognition in adolescents with higher adiposity.

“It is very common for adolescents to experience at least one night of sleep restriction, and given the shift in their circadian rhythm at this age makes them more likely to go to bed later, they are often not obtaining enough sleep on school days,” she told Healio. “It is also notable that there were no differences in cognition between adolescents with healthy weight and those with overweight or obesity when they were adequately rested, which is inconsistent with some past research.”

Stager underlined the importance of promoting healthy sleep durations for adolescents with greater adiposity because they “may be more vulnerable to the negative effects of insufficient sleep.”

“It is also important to advocate for societal changes that allow adolescents to achieve healthy sleep durations (ie, later school start times),” she said.

For more information:

Aaron D. Fobian, PhD, can be reached at afobian@uabmc.edu.