Association between Chronotype, Blue-Light Emitting Media Use, and Sleep in Adolescents
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Many adolescents are chronically sleep deprived due to biological delays in sleep that occur with the onset of puberty. This deprivation heightens risk for psychiatric symptoms, cognitive deficits, and lower academic functioning. Recent rises in electronic media use increases blue wavelength light exposure, which may contribute to sleep deprivation through suppressing melatonin release, further delaying sleep. This study investigated the influence of blue light exposure one hour before bedtime on the relationship between circadian preference (chronotype; i.e., being a “morning type” or “evening type”) and sleep outcomes. Fifty-one participants (63.3% female; 55.1% Caucasian), aged 13-17 years (M=15.14, SD=1.23) were included for analyses. Chronotype was determined via self-report; sleep and blue light exposure during the one hour before bedtime was measured over 7-11 days (Median=8days) using actigraphy. Sleep outcomes included Total Sleep Time (TST), Wake after Sleep Onset (WASO), Sleep Onset Latency (SOL), and Sleep Onset Time (SOT). When controlling for pubertal status and participation time (school vs. holidays), a greater preference for eveningness predicted a later SOT (AdjustedR2=.53, p<.001, β=-.62, p<.001) and marginally predicted a shorter SOL (AdjustedR2=.15, p=.09, β=.36, p=.08) but not TST or WASO. Blue light exposure did not moderate the relationship between chronotype and sleep outcomes. These findings suggest that although media use before bedtime is prevalent in adolescents (M=7.18flux, SD=6.45), sleep interventions focusing on structural (e.g., adjusting school start times) rather than behavioral (e.g., limiting media use) changes may be beneficial, as biologically determined chronotype robustly influences sleep outcomes even in the presence of blue light.