Adolescent Sleep Variability May Impair Brain Development

VBCN - July 2015 Volume 2, No 2

Researchers have confirmed that sleep is imperative for brain development in adolescents, but little is known about how insufficient sleep may alter their brain development. In the first longitudinal study examining the relationship between white matter integrity and sleep during adolescence, researchers have concluded that adolescents with erratic sleep patterns may experience long-term effects on their developing brains.

Because the structure of white matter normally increases in adolescence, sleep variability during that time may lead to impaired brain development, according to the study led by Eva H. Telzer, PhD, Assistant Professor, Department of Psychology, University of Illinois, Urbana-Champaign (Telzer EH, et al. Dev Cogn Neurosci. 2015;14:16-22).

Dr Telzer and colleagues examined the association between sleep and the developing brain by having 48 adolescents complete daily diary checklists for 2 weeks, and then measuring fractional anisotropy via a diffusion tensor imaging (DTI) scan. Daily diary checklists were completed on 2 occasions (wave 1 and wave 2), and were completed 1 year apart. The participants underwent DTI scans a few months after the second wave of daily diary checklists was complete.

“By measuring sleep at 2 time points, once a few months prior to the DTI scan and once 1.5 years prior to the scan, we were able to test whether sleep problems have more immediate or long-term effects on brain development,” the authors explained. “Sleep problems may take time to impact the development of the brain, as alterations in myelination may not occur immediately.”

In wave 1, the adolescents reported an average of 8.3 hours of sleep nightly and had an average sleep duration variability of 93 minutes. In wave 2, the participants reported an average of 8.2 hours of sleep nightly and had an average sleep duration variability of 95 minutes.

The results showed that greater variability in sleep duration 1.5 years before the DTI scan was associated with lower fractional anisotropy in the frontocortical and frontostriatal tracts, association tracts, projection tracts, and in the interhemispheric tract, which undergo significant development during adolescence and are essential for cognitive and executive functioning and emotional regulation.

Sleep duration variability a few months before the DTI scan, however, was not associated with fractional anisotropy, suggesting that regardless of bedtimes or total amount of sleep, variability in teenagers’ sleep durations may have long-term effects on the developing brain.

The researchers therefore suggest that long-term high variability in sleep duration among adolescents may damage their cognitive and socioemotional well-being by altering the development of white matter in the brain.

Further research is needed at the neural and behavioral levels to determine how sleep and changes in white matter are associated with the developmental aspects of affect, cognition, and behavior in adolescents.

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