Discrepancy between self-reported and objective sleep duration among dementia caregivers and noncaregivers

Study Objectives: Poor sleep, including short sleep duration, is common among caregivers of persons with dementia. However, it is unclear whether poor sleep is consistent across both self-reported and objective measures of sleep in caregivers. This study aimed to test the role of caregiving status (caregivers vs noncaregivers) on the discrepancy between self-reported and objective sleep duration. Methods: This was a cross-sectional study. Study participants were community-dwelling caregivers of spouses with dementia (n = 122) and noncaregivers (n = 53). A sleep duration discrepancy index was created by subtracting objective sleep duration measured with 3 consecutive 24-hour periods of actigraphy from self-reported sleep duration measured with the Pittsburgh Sleep Quality Index. Covariates included participants' demographic characteristics, depressive symptoms, positive and negative affects, personal mastery, and caregiving-role overload. Results: Caregivers showed a greater discrepancy in sleep duration than did noncaregivers (-0.46 hour vs 0.22 hour, respectively; P =.003). In a regression model, however, caregiving status was no longer associated with this sleep duration discrepancy, when covariates were accounted for. Higher positive affect was significantly associated with less sleep duration discrepancy (R-2 = 11.3%, P =.014). The Sobel test of mediation showed that 26% of the effect of caregiving on this sleep discrepancy was attributable to caregivers with low positive affect. Conclusions: The findings suggest a potential mediating role of positive affect on the relationship between caregiving status and sleep duration discrepancy. As an aid for understanding the role of lower positive affect, use of actigraphy may help address sleep discrepancy in caregivers.