People who perceive more discrimination in daily life have higher rates of sleep problems, based on both subjective and objective measures, reports a study in Psychosomatic Medicine: Journal of Biobehavioral Medicine, the official journal of the American Psychosomatic Society. The journal is published by Wolters Kluwer.
"Discrimination is an important factor associated with sleep measures in middle-aged adults," according to the report by Sherry Owens, PhD, of West Virginia University, Morgantown, and colleagues. The results add to previous research suggesting that discrimination and chronic stress may lead to sleep difficulties and increased health risks.
Discrimination Related to Both Objective and Subjective Sleep Problems
The study included 441 adults from a nationwide study of health and well-being in middle age and beyond (the MIDUS Study). The participants' average age was 47 years; about one-third were of non-white race/ethnicity. Complete data were available for 361 participants.
Participants wore an activity monitor device for one week to gather data on objective sleep measures--for example, sleep efficiency, calculated as the percentage of time spent in bed that the person was asleep. They also completed subjective sleep ratings -- for example, how often they had sleep problems.
Perceived experiences of discrimination were assessed using a validated "Everyday Discrimination Scale." For example, subjects were asked how often they were treated with less courtesy or respect than others, or how often they were insulted or harassed.
Discrimination scores were analyzed for association with the objective and subjective sleep measures. Objective measures indicated that about one-third of participants had poor sleep efficiency. Subjectively, one-half of subjects rated themselves as having poor sleep quality.
Participants who perceived more discrimination had increased sleep problems, after adjustment for demographic, lifestyle, and health factors. Higher discrimination scores were associated with 12 percent higher odds of poor sleep efficiency and a nine percent increase in the odds of poor sleep quality. Discrimination was also related to (objective) time spent awake after falling asleep and (subjective) overall sleep difficulties.
Non-white subjects had nearly four times the odds of poor sleep efficiency. Otherwise, all differences in sleep measures between white and non-white subjects were related to discrimination.
Older participants and men were more likely to have some types of sleep problems. Age, sex, and mental/physical health factors explained only a small proportion of the effects of discrimination.
Previous studies have suggested that racial/ethnic minorities have worse sleep quality. Inadequate sleep is associated with adverse health outcomes, including increased cardiovascular risks and increased mortality. These consequences of poor sleep may account for some of racial/ethnic variation in health outcomes--possibly reflecting inadequate recovery from chronic daily stressors.
While poor sleep has previously been linked to higher perceived discrimination, the new study is the first to look at how discrimination affects both objective and subjective sleep measures. "The findings support the model that discrimination acts as a stressor than can disrupt subjective and objective sleep," Dr. Owens and coauthors write.
The researchers call for further study to confirm and clarify the implications of their findings. Meanwhile, they believe the study adds a "finer resolution" to previous knowledge the relationship between discrimination and sleep--and suggests a possible "causal pathway" connecting chronic discrimination to sleep problems, and thus to increased health risks.
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