Daily Sleep and Anxious and Depressive Symptoms Among Dementia Caregivers - The Mediation of Cortisol Total Output on High- and Low-Stress Days

Objectives: Dementia family caregivers report poor sleep and mood, typically attributed to chronic stress and managing frequent daily stressors. Although many studies use global retrospective reports of these indicators, the current study examines mechanisms linking sleep, negative affect, stress biomarkers, and high-/low-stress contexts at the daily level, from the biopsychosocial perspective of stressor exposure and reactivity. Method: One hundred seventy-three caregivers (Mage = 61.97, SD = 10.66) were providing care at home and used adult day services (ADS) at least 2 days a week. Caregivers reported their bedtime, wake time, sleep quality, and nighttime problems of the person with dementia (PwD) daily for eight consecutive days, concurrently reporting noncare stressors, negative affect, and providing five salivary cortisol samples per day. We conducted multilevel analysis to examine whether caregiver sleep characteristics overnight (i.e., total time in bed, quality, and PwD sleep problems) were associated with their anxious and depressive symptoms on days where ADS were utilized versus non-ADS days (i.e., low stress vs. high stress), and whether cortisol daily total output as area under the curve (AUCg) mediated the direct associations, at the within- and between-person levels. Results: On high-stress (i.e., non-ADS) days when caregivers had a longer time in bed than usual the night before, they were less anxious on the following day; the direct association was statistically mediated through lower cortisol AUCg during the day. Discussion: Staying longer in bed than usual before an upcoming high-stress day may help dementia family caregivers better regulate cortisol stress reactivity and anxious symptoms.