American time use survey: sleep time and its relationship to waking activities

Abstract

Study objectives: To gain some insight into how various behavioral (lifestyle) factors influence sleep duration, by investigation of the relationship of sleep time to waking activities using the American Time Use Survey (ATUS).

Design: Cross-sectional data from ATUS, an annual telephone survey of a population sample of US citizens who are interviewed regarding how they spent their time during a 24-hour period between 04:00 on the previous day and 04:00 on the interview day.

Participants: Data were pooled from the 2003, 2004, and 2005 ATUS databases involving N=47,731 respondents older than 14 years of age.

Interventions: N/A.

Results: Adjusted multiple linear regression models showed that the largest reciprocal relationship to sleep was found for work time, followed by travel time, which included commute time. Only shorter than average sleepers (<7.5 h) spent more time socializing, relaxing, and engaging in leisure activities, while both short (<5.5 h) and long sleepers (> or =8.5 h) watched more TV than the average sleeper. The extent to which sleep time was exchanged for waking activities was also shown to depend on age and gender. Sleep time was minimal while work time was maximal in the age group 45-54 yr, and sleep time increased both with lower and higher age.

Conclusions: Work time, travel time, and time for socializing, relaxing, and leisure are the primary activities reciprocally related to sleep time among Americans. These activities may be confounding the frequently observed association between short and long sleep on one hand and morbidity and mortality on the other hand and should be controlled for in future studies.

Figure 1

A. Average weekday (Mon–Fri) sleep time depending on age range and gender (N_male=10,137, N_female=13,188). Sleep time includes ATUS tiers 01.01.01 “sleeping,” 01.01.02 “sleeplessness,” and 01.01.99 “sleeping not elsewhere classified” (for examples see Methods). B. Average sleep time depending on age range and day of the week (N=46,888). Each day covers a period from 04:00 on the same day to 04:00 on the next day (e.g., Sunday covers Sunday morning 04:00 to Monday morning 04:00.). Error bars are only shown for weekend days for clarity. C. Proportion of respondents reporting sleeplessness (ATUS category 01.01.02) depending on age range and gender (N_male=20,393, N_female=26,495). The ATUS User's Guide gives the following examples for the category “sleeplessness”: insomnia, tossing and turning, lying awake, counting sheep. Error bars in a, b, and c represent standard errors calculated with the replicate variance method described in the ATUS User's Guide.

Figure 2

A. Average change in weekday (Mon–Fri) waking activity time depending on sleep time category (N=23,325) based on multiple linear regression models adjusting for age, gender, ethnicity, educational attainment, income, presence of partner, and presence of children. The 7.5 h to <8.5 h sleep time category served as reference. Upper boundaries of 1 h sleep time ranges are shown on the abscissa, except for the lowest and highest category, which extend to minimum and maximum sleep time. For work time, separate models were run for the whole group (Work) and restricting data to those who worked on the interview day (Work > 0 min).B. Average change in weekend (Sat+Sun) waking activity time depending on sleep time category (N=23,563).

Figure 3

A. Average weekday (Mon–Fri) work time depending on age range and gender (N_male=10,137, N_female=13,188). Work time includes ATUS tier 05: All “working and work related activities” (see Appendix). Error bars represent standard errors calculated with the replicate variance method described in the ATUS User's Guide. B. Average sleep time and work time depending on quartile of weekly pay and multiple job status for weekdays (Mon–Fri). Of the 13,130 respondents with income, 9.3% reported work in multiple jobs. Error bars represent standard errors calculated with the replicate variance method described in the ATUS User's Guide. C. Average change in weekday (Mon–Fri) work time depending on age range and gender for below average (<7.5 h) and above average (> 8.5 h) sleepers (N=23,325) based on multiple linear regression models adjusting for age, gender, ethnicity, educational attainment, income, presence of partner, and presence of children. The 7.5 h to <8.5 h sleep time category served as reference. Error bars represent standard errors.