Sleep duration and the cortisol awakening response in dementia caregivers utilizing adult day services

Author(s): Leggett, A.N., Liu, Y., Klein, L.C. and Zarit, S.H.

Published In: Health Psychology, 35 (5): 465-473

Study Aim/Purpose: This study examines the effect of sleep duration on the cortisol awakening response (CAR) and whether use of adult day service respite can counteract that negative effect. 

Summary of Methods: The study followed 158 family caregivers who lived with individuals with dementia who were attending ADS at least two days a week. Each respondent completed an initial in-person interview to collect background information; engaged in daily evening telephone interviews when they reported information they documented in daily diaries about their health, well-being, and daily care and non-care related activities; and provided five daily saliva samples to measure cortisol awakening response (CAR), defined as the extent of change in cortisol levels from awakening to 30 minutes after awakening and total daily cortisol output measured as cortisol area under the curve with respect to ground (AUC-G). The key measures analyzed for this study were CAR and cortisol levels, sleep duration, overnight care-related stressors, and depressive mood symptoms. 

Summary of Results: The study found that sleeping shorter than one’s average duration and having less depressive mood were associated with larger CAR. On non-ADS days there was a significant association between length of caregiver sleep beyond his or her average sleep length and a smaller (or “blunted”) CAR. Attending ADS the day before had no significant positive effect on the CAR. However, on the morning of ADS use days, regardless of how much longer than average a caregiver slept, cortisol increases were observed. Statistical analysis models adjusted for many covariates found no significant effects of any covariates on the relationship between ADS use and the CAR. 

Study Limitations (as cited by authors): The authors recognize the selection bias of the study given that participants self-selected to use ADS and were available to participate in the intensive data collection for this eight-day study. They also note that this report did not include any objective measures of sleep time, and its self-report measures of sleep durations may overestimate total sleep time. 

Authors’ Discussion/Conclusions: The authors suggest that the overriding effect of ADS on the association between prolonged sleep and a maladaptive CAR pattern indicates that respite interventions have a key role in providing physiological recovery for caregivers. They conclude that providing caregivers with respite may have positive effects on starting the day with proper arousal and energy, and may reduce burden, allostatic load and poor health outcomes. They also suggest that given the importance of sleep duration for health, ADS programs may consider offering sleep hygiene programs to improve sleep of both people with dementia and their caregivers. The authors also recommend future research on the mechanisms through which ADS can moderate associations between sleep and cortisol regulation.