Mediating Role of Anxiety Between Perceived Discrimination and Sleep Quality in the Midlife in the United States (MIDUS) Study

Poor sleep quality is associated with poorer mental and physical health, including depression and hypertension, particularly in racial/ethnic minorities.  Limited work has assessed the association between discrimination and sleep outcomes by racial/ethnic group.  Among the existing studies, the role of anxiety is not well studied.  Using data the Midlife Development in the United States (MIDUS) study at Waves I and II, we examined associations between discrimination, race, and sleep quality.  Perceived discrimination was measured using the 9-item version of the Williams Everyday Discrimination Scale.  A 4-category variable was used to assess discrimination across the study period based on quartile rankings at each wave.  The analytic sample (N=1677) was classified as follows: low-stable, decrease, increase, and high-stable.  A 5-point Likert-like scale (1 = never, 5 = almost always) assessed sleep quality based on the frequency of trouble falling asleep, waking in the middle of the night with trouble getting back to sleep, and waking very early with trouble getting back to sleep.  The mean of the responses was calculated, with greater values representing greater sleep quality (range 1-5; Cronbach’s alpha = 0.82). Controlling for important sociodemographic covariates, respondents who experienced decreasing, increasing, and consistently high levels of perceived discrimination had poorer sleep quality than respondents who reported consistently low discrimination (p=0.01).  Anxiety was a significant partial mediator for the high-stable (11.7%, P < 0.05) and the decrease (16.8%, P < 0.05) groups but now the increase group (7.0%, P > 0.05).   In light of current evidence of the negative physiologic impact of poor sleep quality, future research to better understand the psychosocial correlates of sleep quality is warranted.