Adolescents With Higher Adiposity More Vulnerable to Cognitive Impairments From Poor Sleep
Key Clinical Points:
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In contrast, adolescents with lower body fat did not experience a decline in performance following the same sleep restriction.
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Improved sleep hygiene and duration in this group may positively impact their cognitive health.
Adolescents with higher levels of adiposity may be more susceptible to the cognitive effects of sleep restriction than those with lower adiposity, according to a recent single-blind randomized crossover trial published in JAMA Neurology.
“Most studies…use BMI as the only indicator of adiposity. This may affect outcomes, as BMI does not differentiate between adipose tissue and muscle mass,” authors wrote in the study. “To our knowledge, only 1 study has investigated sleep in this way, and that study only used 1 performance-based cognitive measure.”
Conducted from September 2020 to October 2022, researchers assessed 61 adolescents aged 14-19 years, dividing them into 2 groups: “healthy weight” (BMI greater than or equal to the 5th percentile and below the 85th percentile) and overweight or obesity.
Following a 2-day washout period of adequate sleep, participants completed 2 sleep conditions: adequate sleep (mean duration of 8 hours, 54 minutes) and restricted sleep (mean duration of 4 hours, 12 minutes). Global and fluid cognition, cognitive flexibility, working and episodic memory, attention, and processing speed were assessed using The National Institutes of Health Cognitive Toolbox. The Stroop task assessed inhibition.
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The study found that adolescents classified as overweight or obese had significantly poorer cognitive outcomes following restricted sleep. Global cognition scores in that group dropped from a mean of 103.2 with adequate sleep to 98.0 with restricted sleep. Adolescents who were overweight or obese also had poorer attention scores (mean [SD], 80.0 [2.3]) compared to adolescents with healthy weight (mean [SD], 88.4 [SD, 2.3]) following restricted sleep. However, adolescents with a healthy weight did not show any differences in these areas when their sleep was restricted.
Findings showed similar results for total body fat percentage (TBF%). Adolescents with TBF% above 42 had poorer processing speed with restricted sleep. Yet, the relationship between sleep and attention was consistent regardless of TBF%.
The cutoffs for TBF% associated with significant differences in cognitive function were high—42%, 55%, and 42%--indicating differences for approximately 14.75% of the total study sample. “Thus, the TBF% analyses highlight increased risk of sleep-related cognitive impairment only for adolescents with obesity or severe obesity compared to all adolescents with overweight or obesity,” researchers said in the study. “This highlights a reason for caution in using BMI groupings in research, as those with overweight may be incorrectly identified as having greater risk for negative health outcomes when their risk is more similar to that of adolescents with healthy weight.”
“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,” researchers concluded.
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