Older participants and men were more likely to have some types of sleep problems. Photograph:( Getty )
People who perceive more discrimination in daily life have higher rates of sleep problems, based on both subjective and objective measures, according to a new study.
The study included 441 adults whose average age was 47 years; about one-third were of non-white race/ethnicity.
"Discrimination is an important factor associated with sleep measures in middle-aged adults," said Sherry Owens from West Virginia University in the US.
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 analysed 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 per cent higher odds of poor sleep efficiency and a nine per cent 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.
The study was published in Psychosomatic Medicine: Journal of Behavioural Medicine.