When children grow up
By Karen Matthews, PhD
It has long been established that individual behaviors, such as smoking, physical inactivity, high fat, high sugar diets, excessive alcohol consumption and unprotected sex are related to diverse health outcomes. Estimates suggest that between 40-50 percent of early mortality is related to individual behaviors (McGinnis & Foege, 1993; Mokdad, Marks, Stroup, & Gerberding, 2004). In general, health-damaging behaviors are more common in lower socioeconomic status (SES) individuals, at least in part due to the environmental exposures they experience. Missing from the list of potentially-health damaging behaviors is poor sleep.
Approximately one-third of our adult lives is spent sleeping and good sleep is considered restorative and essential for daily functioning and well being. However, epidemiological studies suggest that inadequate sleep is not only health-damaging in the short-run, but also potentially lethal in the long run. A series of meta-analyses show that individuals who report typically sleeping 7 to 8 hours per night are at reduced risk for early cardiovascular disease, mortality, obesity and diabetes compared to shorter or longer sleepers (Cappuccio et al., 2008; Cappuccio, Cooper, D'Elia, Strazzullo, & Miller, 2011; Gallicchio & Kalesan, 2009). Longer sleep may be associated with adverse health outcomes because of subclinical illness, pain or depression leading to excessive fatigue and sleep. Demonstrated by sleep restriction experiments, shorter sleep may be associated through alterations in hypothalamic activity, increases in nocturnal growth hormone secretion and cortisol, and increased sympathetic nervous system activity, which have downstream effects on appetite, glucose metabolism and blood pressure regulation (Knutson, 2010).
Other than studies of insomnia patients, fragmented sleep or frequent awakenings during the night has been the subject of far fewer investigations than sleep duration. By and large, complaints of trouble sleeping and frequent awakenings are associated with cardiometabolic diseases (Mezick, Hall, & Matthews, 2011). As with the studies of sleep duration, studies of nighttime awakenings are largely measured by self-report, which are modestly associated with objective measures of sleep.
Noted by Buckhalt and El-Sheikh, many aspects of the psychosocial and physical environment influence sleep and can vary by SES, including uncomfortable beds, inadequate heating and cooling, noise, irregular routines and stress. Thus, it is reasonable to expect that lower SES individuals would have less adequate sleep (Matthews & Gallo, 2011). We have demonstrated in two samples of black and white middle-aged adults that lower SES individuals have less efficient sleep (taking longer to fall asleep or being awake longer after sleep onset) based on in-home objective measures and lower quality sleep based on self-report (Hall et al. 2009; Mezick et al. 2008). These studies also show striking ethnic differences in sleep, with African Americans in general having shorter sleep, less deep sleep and less efficient sleep, usually independent of SES (see also Lauderdale et al., 2006).
Taken together, what do these findings suggest? First, poor sleep should be added to the list of health-damaging behaviors. Second, poor sleep is likely to occur in low SES environments and to be experienced by African-Americans. Third, poor sleep may be a pathway connecting low SES with poor health but has not been demonstrated as of yet. Fourth, to the extent sleep can be improved by behavioral and environmental interventions in adults, the impact of low SES on health may be ameliorated.
Cappuccio, F. P., Cooper, D., D'Elia, L., Strazzullo, P., & Miller, M. A. (2011). Sleep duration predicts cardiovascular outcomes: a systematic review and meta-analysis of prospective studies. European Heart Journal, 32, 1484-1492.
Cappuccio, F. P., Taggart, F. M., Kandala, N. B., Currie, A., Peile, E., Stranges, S., & Miller, M. A. (2008). Meta-analysis of short sleep duration and obesity in children and adults. Sleep, 31, 619-626.
Hall, M., Matthews, K. A., Kravitz, H., Gold, E., Buysse, D., Bromberger, J. T., … Sowers, M. F. (2009). Race and financial strain are independent correlates of sleep in mid-life women: The SWAN Sleep Study. Sleep, 32, 72-82.
Gallicchio, L., & Kalesan, B. (2009). Sleep duration and mortality: A systematic review and meta-analysis. Journal of Sleep Research, 18, 148-158.
Knutson, K. L. (2010). Sleep duration and cardiometabolic risk: a review of the epidemiologic evidence. Best Practice & Research Clinical Endocrinology & Metabolism, 24, 731-743.
Lauderdale, D. S. (2006). Objectively measured sleep characteristics among early-middle-aged adults. American Journal of Epidemiology, 164, 5-16.
Matthews, K. A., & Gallo, L. C. (2011). Psychological perspectives on pathways linking socioeconomic status and physical health. Annual Review of Psychology, 62, 501-530.
McGinnis, J. M., & Foege, W. H. (1993). Actual causes of death in the United States. JAMA, 270, 2207-2212.
Mezick, E. J., Hall, M., & Matthews, K. A. (2011). Are sleep and depression independent or overlapping risk factors for cardiometabolic disease? Sleep Medicine Reviews, 15, 51-63.
Mezick, E. J., Matthews, K. A., Hall, M., Strollo, P. J., Jr., Buysse, D. J., Kamarck, T. W. … Reis, S.E. (2008). Influence of race and socioeconomic status on sleep: Pittsburgh SleepSCORE project. Psychosomatic Medicine, 70, 410-416.
Mokdad, A. H., Marks, J. S., Stroup, D. F., & Gerberding, J. L. (2004). Actual causes of death in the United States, 2000. JAMA, 291, 1238-1245.
Sekine, M., Chandola, T., Martikainen, P., McGeoghegan, D., Marmot, M., & Kagamimori, S. (2006). Explaining social inequalities in health by sleep: the Japanese civil servants study. Journal of Public Health (Oxford), 28, 63-70.
Karen A. Matthews, PhD, is the distinguished professor of psychiatry, professor of epidemiology and psychology, and program director of the cardiovascular behavioral medicine research training program at the University of Pittsburgh. Her research has focused on behavioral risk factors for cardiovascular and their determinants at key developmental transitions. She currently is conducting research on the influence of menopause on women’s health; development of behavioral risk factors in adolescence and young adulthood; sleep disturbance as a possible risk factor for cardiovascular disease; and the pathways connecting sociodemographic factors and ethnicity with poor cardiovascular health. Matthews was a member of the MacArthur Foundation Network on Socioeconomic Status and Health and was the 2005 recipient of the APA Award for Distinguished Scientific Applications of Psychology.