Individuals who perceive themselves as being the target of daily discrimination are more likely to suffer from sleep problems, based on both objective and subjective measures, according to a new study published in Psychosomatic Medicine: Journal of Biobehavioral Medicine.
Although poor sleep has been previously linked to higher levels of perceived discrimination, the new study is the first to investigate how discrimination affects both objective and subjective sleep measures. Objective measures are those based on testable facts and are not influenced by personal bias or feelings; subjective measures are open to greater interpretation due to personal experience, opinion, or emotions.
For the study, researchers analyzed the data of 441 middle-age adults (average age 47) who were part of a nationwide study of health and well-being (MIDUS Study). About one-third of the subjects were of non-white race/ethnicity. Complete data were available for 361 participants.
For one week, participants wore an activity monitoring device to collect data on objective sleep measures, such as “sleep efficiency,” calculated as the percentage of time spent in bed that the person was asleep. They also completed subjective sleep ratings in which they reported how often they had sleep problems.
Experiences of perceived discrimination were assessed using a validated “Everyday Discrimination Scale.” For example, participants reported how often they were treated with less courtesy or respect than others, or how often they were insulted or harassed.
Researchers then compared the discrimination scores to the objective and subjective sleep measures. Objective measures indicated that about one-third of participants had poor sleep efficiency. Subjectively, one-half of the participants rated themselves as having poor sleep quality.
Discrimination was related to (objective) time spent awake after falling asleep and (subjective) overall sleep difficulties. 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, after adjustment for demographic, lifestyle, and health factors.
Older participants and men were more likely to have some types of sleep problems, but age, sex, and mental/physical health factors explained only a small proportion of the effects of discrimination. 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 perceived discrimination.
“Discrimination is an important factor associated with sleep measures in middle-aged adults,” said Sherry Owens, PhD, of West Virginia University, and colleagues in the report.
Previous research has suggested that racial and ethnic minorities have poorer sleep quality in general. Poor sleep is tied to many health conditions, including increased cardiovascular risks and increased mortality. In fact, inadequate sleep — perhaps being the result of chronic daily stress — may account for some of the racial/ethnic discrepancies in health outcomes.
The researchers say that more studies are needed to further confirm and clarify the implications of their findings. Meanwhile, they say the study adds a “finer resolution” to previous knowledge of the connection between discrimination and sleep. It also suggests a possible “causal pathway,” connecting chronic discrimination to sleep problems, and therefore to increased health risks.
Source: Wolters Kluwer Health