Sleep: a health imperative

Abstract

Chronic sleep deficiency, defined as a state of inadequate or mistimed sleep, is a growing and underappreciated determinant of health status. Sleep deprivation contributes to a number of molecular, immune, and neural changes that play a role in disease development, independent of primary sleep disorders. These changes in biological processes in response to chronic sleep deficiency may serve as etiological factors for the development and exacerbation of cardiovascular and metabolic diseases and, ultimately, a shortened lifespan. Sleep deprivation also results in significant impairments in cognitive and motor performance which increase the risk of motor vehicle crashes and work-related injuries and fatal accidents. The American Academy of Sleep Medicine and the Sleep Research Society have developed this statement to communicate to national health stakeholders the current knowledge which ties sufficient sleep and circadian alignment in adults to health.

Keywords: Sleep deficiency; accidents; cancer; cardiovascular disease; circadian misalignment; mortality; obesity; sleep duration; stroke; type 2 diabetes.

Figure 1

Percentage of adults in the United States by reported usual sleep durations and by number of sleep-related difficulties. Data taken from the National Health and Nutrition Examination Survey (NHANES), cycles (2005-2006 and 2007-2008). A total of 10,896 respondents aged ≥ 20 years completed survey questions on sleep duration and sleep-related difficulties. Sleep duration categories were based on responses to the question “how much sleep do you usually get at night on weekdays or workdays?” Responses to 6 questions from the Functional Outcomes of Sleep Questionnaire were used to determine the number of sleep-related difficulties.

Figure 2

Percentage of adult men and women in the United States, by age group, reporting an average ≤ 6 h of sleep in 1985 and in 2004. Data from the National Health Interview Survey, 2004, and Schoenborn. Adapted from CDC.

Figure 3

Mortality harard ratios for various reported sleep durations for men and women. Data collected from 636,095 men and 480,841 women in the Cancer Prevention Study II (1982-1988). Both men and women with a usual sleep duration of 7 h had the best survival. Participants reporting sleep durations ≤ 6 h and ≥ 8 h had significantly increased mortality hazard. Adapted from Kripke et al.

Figure 4

Relationship between sleep duration and prevalence of hypertension from the Sleep Heart Health Study. Data are adapted from Gottlieb et al. Odds ratios are for the presence of hypertension, from categorical logistic regression models using 7 to < 8 h sleep per night as the referent category. Model 1 was unadjusted. Model 2 was adjusted for age, sex, race, and apnea-hypopnea index. Model 3 was adjusted for all covariates in Model 2 plus body mass index.

Figure 5

Curvilinear relationship between body mass index (BMI) and average hours of sleep. “Average nightly sleep” was based on data collected from a 6-day sleep diary and was calculated as the sum of the hours between bedtime and arising, divided by 6. After adjustment for age and sex, those sleeping more and less than 7.7 h/night had an increased BMI. Adapted from Taheri et al.

Figure 6

Relationships between hours of sleep and prevalence of type 2 diabetes and impaired glucose tolerance. Data adapted from Gottlieb et al. Odds ratios are for the presence of diabetes and impaired glucose tolerance, from categorical logistic regression model adjusted for age, race/ethnicity, apnea-hypopnea index, study site, and waist girth, using 7 to 8 h of sleep/night as the referent category. Usual sleep times ≤ 6h or ≥ 9h/night were associated with an increased prevalence of type 2 diabetes and impaired glucose tolerance.