Author(s): Knutson KL, Van Cauter E, Rathouz PJ, DeLeire T, Lauderdale DS
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Abstract STUDY OBJECTIVES: To determine (1) whether short sleep has increased over 31 years; (2) whether trends in short sleep differed by employment status; (3) which sociodemographic factors predict short sleep; and (4) how short sleepers spend their time. DESIGN: Time diaries from eight national studies conducted between 1975 and 2006. PATIENTS OR PARTICIPANTS: U.S. adults > or = 18 years. MEASUREMENTS AND RESULTS: Short sleepers were defined as those reporting < 6 hours of sleep in their time diary. Unadjusted percentages of short sleepers ranged from 7.6\% in 1975 to 9.3\% in 2006. The 1998-99 study had the highest odds of short sleep. The odds ratio for the 31-year period predicting short sleep was 1.14 (95\% CI: 0.92, 1.50, P = 0.22), adjusting for age, sex, education, employment, race, marital status, income, and day of week. When stratified by employment, there was a significant increase for full-time workers (P = 0.05), who represented over 50\% of participants in all studies, and a significant decrease for students (P = 0.01), who represented < 5\% of participants. The odds of short sleep were lower for women, those > or = 65 years, Asians, Hispanics, and married people. The odds were higher for full-time workers, those with some college education, and African Americans. Short sleepers in all employment categories spent more time on personal activities. Short sleepers who were full- and part-time workers spent much more time working. CONCLUSIONS: Based on time diaries, the increase in the odds of short sleep over the past 31 years was significant among full-time workers only. Work hours are much longer for full-time workers sleeping < 6 hours.
This article was published in Sleep
and referenced in Journal of Sleep Disorders & Therapy