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

Abstract

Summary Depression is associated with disturbances to sleep and the 24-hour sleep-wake pattern (known as the rest-activity rhythm or RAR). However, there remains a need to identify the specific sleep/RAR correlates of depression symptom severity in zpopulation sub-groups, 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 n=57 (mean age=74, standard deviation=7.4) strained dementia caregivers who were currently without clinical depression. We derived sleep measures from polysomnography and actigraphy, modeled 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 correlations ranged from 0.23–0.32): 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 independently associated 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), 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) uniquely correlate 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.

Moderators of Response to Cognitive Behavior Therapy for Major Depression in Patients With Heart Failure

“…We found that the effect of CBT over UC was smaller in patients who had less stable activity patterns and narrower active periods at baseline, likely due to earlier evening settling. These activity characteristics have been previously associated with depression symptoms, e.g., studies examining the stability of activity patterns across days 30,31 and the active period length [31][32][33][34] . Unstable activity patterns and narrower active periods may reflect less regular and consistent engagement with rewarding social and leisure-time activities.…”

“…Unstable activity patterns could also reflect the burden of comorbidities or circadian misalignment (e.g., poor coordination between the timing of biological and/or psycho-behavioral processes). Future work is needed to clarify why these aspects of activity patterns are associated with depression [30][31][32][33][34] and a lack of benefit when given CBT vs. UC. Prior research has shown that bright light therapy 35,36 and exercise 37 can stabilize activity rhythms, and it is plausible that activity planning occurring in CBT could deliberately prolong the active period.…”

Rest-activity rhythm profiles associated with manic-hypomanic and depressive symptoms

“…Delayed sleep-wake timing has also previously been associated with mood disturbances (Morita et al, 2015). Prior literature that has found shorter active periods (Smagula et al, 2015b; Smagula et al, 2017) and later timing (Robillard et al, 2015; Smagula et al, 2015a; Smagula et al, 2015b) objectively mark depression symptoms, and that later timing (Robillard et al, 2015) and RAR irregularity (Gonzalez et al, 2014; Jones et al, 2005; Robillard et al, 2015; Robillard et al, 2016) mark bipolar disorder.…”

“…For example, several sub-groups with distinct combinations of multiple RAR characteristics exist among community-dwelling older men (Smagula et al, 2015b); these sub-groups differ in the rate of depression symptom increases independent of other covariates including sleep measures. We also recently observed, among older strained dementia caregivers, that several inter-correlated RAR measures (i.e., earlier evening settling, a shorter active period, and having less steep/“square-like” RARs) marked greater levels of sub-threshold depression symptom severity (Smagula et al, 2017). This suggests individual RAR characteristics cluster together within people, and indicates the need to describe the multivariate RAR profiles prevalent in public health relevant groups (in addition to examining the health relevance of individual RAR variables).…”

Rest-activity rhythms characteristics and seasonal changes in seasonal affective disorder

“…One set of behavioral factors that are potentially related to changes in mood state are characteristics of the 24-hour activity pattern (known as the rest-activity rhythm or RAR). For example, people with depression symptoms tend to have less regular RARs (Luik, Zuurbier et al, 2013; Luik, Zuurbier et al, 2015), narrower active periods (Smagula, Boudreau et al, 2015; Smagula, Krafty et al, 2017), and often later activity timing (Robillard, Hermens et al, 2015; Smagula, Boudreau et al, 2015). Less research has examined RARs in SAD.…”