Caffeine use is ubiquitous among adolescents and may be harmful to sleep, with downstream implications for health and development. Research has been limited by self-reported and/or aggregated measures of sleep and caffeine collected at a single time point. This study examines bidirectional associations between daily caffeine consumption and electroencephalogram-measured sleep among adolescents and explores whether these relationships depend on timing of caffeine use.
Ninety-eight adolescents aged 11-17 (M=14.38, SD=1.77; 50% female) participated in 7 consecutive nights of at-home sleep electroencephalography and completed a daily diary querying morning, afternoon, and evening caffeine use. Linear mixed effects regressions examined relationships between caffeine consumption and total sleep time, sleep-onset latency, sleep efficiency, wake after sleep onset, and time spent in sleep stages. Impact of sleep indices on next-day caffeine use was also examined.
Increased total caffeine consumption was associated was increased sleep-onset latency (β=.13; 95% CI=.06,.21; p<.001) and reduced total sleep time (β=-.17; 95% CI=-.31,-.02; p=.02), sleep efficiency (β=-1.59; 95% CI=-2.51,-.67, p<.001), and rapid-eye movement sleep (β=-.12; 95% CI=-.19,-.05; p<.001). Findings were driven by afternoon and evening caffeine consumption. Reduced sleep efficiency was associated with increased afternoon caffeine intake the following day (β=-.006; 95% CI=-.012,-.001; p=.01).
Caffeine consumption, especially afternoon and evening use, impacts several aspects of adolescent sleep health. In contrast, most sleep indicators did not affect next-day caffeine use, suggesting multiple drivers of adolescent caffeine consumption. Federal mandates requiring caffeine content labeling and behavioral interventions focused on reducing caffeine intake may support adolescent sleep health.