Caffeine consumption and weekly sleep patterns in US seventh-, eighth-, and ninth-graders.
OBJECTIVE
To survey caffeine use by seventh-, eighth-, and ninth-graders and relate its use to age, sex, sleep characteristics, and day of week


METHODS
Students kept a daily, 2-week diary of their sleep times and use of caffeine containing drinks and foods. Data were analyzed by fitted multiple regression models


RESULTS
A total of 191 students participated. Caffeine intake ranged between 0 and 800 mg/d. Mean use over 2 weeks ranged up to 379.4 mg/d and averaged 62.7 mg/d (corrected for underrepresentation in our sample of boys, who consumed more caffeine). Higher caffeine intake in general was associated with shorter nocturnal sleep duration, increased wake time after sleep onset, and increased daytime sleep. SLEEP PATTERNS: Mean bedtime was 10:57 PM, and mean wake time was at 7:14 AM. Older children delayed bedtime longer on weekends, and younger ones had longer nightly sleep durations. Sleep duration lengthened on weekends, reflecting the combined effects of the circadian timing system and a mechanism that regulates the duration of sleep. Caffeine (soda) consumption also increased on weekends, for reasons that may be primarily social


CONCLUSIONS
Regardless of whether caffeine use disturbed sleep or was consumed to counteract the daytime effect of interrupted sleep, caffeinated beverages had detectable pharmacologic effects. Limitation of the availability of caffeine to teenagers should therefore be considered.
Pollak
Charles P
CP
Division of Sleep Medicine, Department of Neurology, Ohio State University, Columbus, Ohio 43210, USA.
Bright
David
D
D000293:Adolescent; D001628:Beverages; D002110:Caffeine / Q000008:administration & dosage / Q000009:adverse effects*; D002648:Child; D002940:Circadian Rhythm / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D009820:Ohio / Q000453:epidemiology; D012044:Regression Analysis; D012890:Sleep / Q000187:drug effects* / Q000502:physiology; D012893:Sleep Wake Disorders / Q000139:chemically induced / Q000453:epidemiology; D013334:Students / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires
D002110:Caffeine