Rest-activity rhythm and sleep characteristics associated with depression symptom severity in strained dementia caregivers

Stephen F Smagula; Robert T Krafty; Briana J Taylor; Lynn M Martire; Richard Schulz; Martica H Hall

doi:10.1111/jsr.12549

Rest-activity rhythm and sleep characteristics associated with depression symptom severity in strained dementia caregivers

J Sleep Res. 2017 Dec;26(6):718-725. doi: 10.1111/jsr.12549. Epub 2017 May 10.

Authors

Stephen F Smagula¹, Robert T Krafty², Briana J Taylor³, Lynn M Martire⁴, Richard Schulz^{1

5}, Martica H Hall¹

Affiliations

¹ Department of Psychiatry, Western Psychiatric Institute and Clinic of University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
² Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA.
³ Department of Psychology, University of Pittsburgh, Pittsburgh, PA, USA.
⁴ Department of Human Development and Family Studies, Pennsylvania State University, State College, PA, USA.
⁵ University Center for Social and Urban Research, University of Pittsburgh, Pittsburgh, PA, USA.

Abstract

Depression is associated with disturbances to sleep and the 24-h sleep-wake pattern (known as the rest-activity rhythm: RAR). However, there remains a need to identify the specific sleep/RAR correlates of depression symptom severity in population subgroups, such as strained dementia caregivers, who are at elevated risk for major depressive disorder. We assessed the cross-sectional associations of sleep/RARs with non-sleep depression symptom severity among 57 (mean age: 74 years, standard deviation: 7.4) strained dementia caregivers who were currently without clinical depression. We derived sleep measures from polysomnography and actigraphy, modelled RARs using a sigmoidally transformed cosine curve and measured non-sleep depression symptom severity using the Hamilton Depression Rating Scale (HRDS) with sleep items removed. The following sleep-wake measures were associated with greater depression symptom severity (absolute Spearman's correlations ranged from 0.23 to 0.32): more time awake after sleep onset (WASO), higher RAR middle level (mesor), relatively shorter active periods (alpha), earlier evening settling time (down-mesor) and less steep RARs (beta). In multivariable analysis, high WASO and low RAR beta were associated independently with depression symptom severity. Predicted non-sleep HDRS means (95% confidence intervals) in caregivers with and without these characteristics were: normal WASO/beta = 3.7 (2.3-5.0), high WASO/normal beta = 5.5 (3.5-7.6), normal WASO/low beta = 6.3 (3.6-8.9) and high WASO/low beta = 8.1 (5.3-10.9). Thus, in our sample of strained caregivers, greater sleep fragmentation (WASO) and less sustained/sharply segregated resting and active periods (low RAR beta) correlate uniquely with depression symptom severity. Longitudinal studies are needed to establish whether these independent sleep-wake correlates of depression symptoms explain heightened depression risk in dementia caregivers.

Keywords: actigraphy; activity rhythms; depression symptoms; sleep characteristics; sub-syndromal.

MeSH terms

Actigraphy
Aged
Caregivers / psychology*
Cross-Sectional Studies
Dementia*
Depression / complications
Depression / physiopathology*
Depression / psychology*
Depressive Disorder, Major / complications
Depressive Disorder, Major / physiopathology
Depressive Disorder, Major / psychology
Female
Humans
Longitudinal Studies
Male
Rest*
Sleep Wake Disorders / complications
Sleep Wake Disorders / physiopathology
Sleep Wake Disorders / psychology
Sleep*
Wakefulness*

Abstract

MeSH terms

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