. Author manuscript; available in PMC: 2014 Aug 1.

Published in final edited form as: Sleep Med Rev. 2013 Jan 21;17(4):255–262. doi: 10.1016/j.smrv.2012.07.002

Table 1.

Summary of Epidemiological Studies in America that Examine Trends in Sleep over Time

Source	Study Design	Sample	Results	Limitations
NSF, 2005¹²	Random interviews	Sleep in America poll	Americans sleeping ≤ 8 h in 2001, 38%; 2002, 30%; in 2005, 26%	Response bias of self-reports
Stamatakis et al, 2007⁵	Questionnaire data	Alameda County Health and Ways of Living Study (1965, 1974, 1983, 1994, 1999), n=6928	Overall percentage of short sleepers increased over time for African Americans (26% in 1965 to 54% in 1999), Hispanics (12% in 1965 to 37% in 1999) and whites (15% in 1965 to 25% in 1999).	Response bias of self-reports
Knutson et al, 2010¹⁷	Meta-analysis of 8 national studies, 1975–2006	American's Use of Time Series (1975,1985,199–99); Environmental Protection Agency Time Use Study (1992–94); American Time Use Survey (ATUS) (2003,2004,2005,2006)	Odds of short sleep higher for full-time workers, those with some college education, and African Americans. Short sleepers were 7.6% in 1975, 9.3% in 2006	Time diaries, total daily sleep not limited to sleep at night
Luckhaupt, 2010¹⁴	Cross-sectional epidemiologic survey	2004–07 National Health Interview Survey (NHIS);, employed adults; ages ≤18 y, n=66,099	Proportion of 6 h sleepers was 30.7% in 2004 (95% CI: 1.03–1.13) and 28.4% in 2007; mean proportion of short sleepers 37.2% (95% Cl: 1.24–1.35) for blacks and 28.8% for whites	Sample limited to the employed; response bias of self-reports
Robinson et al, 2010¹⁶	Time diaries	2003–2007 ATUS, ages 18–64 y	Sleep in America increased; in 1965, 56 hrs/week, in 2007, 59 hr/week	Weekly estimates, does not limit sleep to nightly sleep or does not account for making up for lost sleep during the weekend.

Abbreviations: CI, confidence interval