Study objectives

Variable daily sleep (ie, higher intraindividual variability; IIV) is associated with negative health consequences, but potential physiological mechanisms are poorly understood. This study examined how the IIV of sleep timing, duration, and quality is associated with physiological dysregulation, with diurnal cortisol trajectories as a proximal outcome and allostatic load (AL) as a multisystem distal outcome.

Methods

Participants are 436 adults (Mage ± standard deviation = 54.1 ± 11.7, 60.3% women) from the Midlife in the United States study. Sleep was objectively assessed using 7-day actigraphy. Diurnal cortisol was measured via saliva samples (four/day for 4 consecutive days). AL was measured using 23 biomarkers from seven systems (inflammatory, hypothalamic-pituitary-adrenal axis, metabolic glucose and lipid, cardiovascular, parasympathetic, sympathetic) using a validated bifactor model. Linear and quadratic effects of sleep IIV were estimated using a validated Bayesian model.

Results

Controlling for covariates, more variable sleep timing (p = .04 for risetime, p = .097 for bedtime) and total sleep time (TST; p = .02), but not mean sleep variables, were associated with flatter cortisol diurnal slope. More variable sleep onset latency and wake after sleep onset, later average bedtime, and shorter TST were associated with higher AL adjusting for age and sex (p-values < .05); after controlling for all covariates, however, only later mean bedtime remained significantly associated with higher AL (p = .04).

Conclusions

In a community sample of adults, more variable sleep patterns were associated with blunted diurnal cortisol trajectories but not with higher multisystem physiological dysregulation. The associations between sleep IIV and overall health are likely complex, including multiple biopsychosocial determinants and require further investigation.

OBJECTIVE:Insomnia and major depressive disorders (MDD) often co-occur, and such comorbidity has been associated with poorer outcomes for both conditions. However, individual differences in depressive symptom trajectories during and after treatment are poorly understood in comorbid insomnia and depression. This study explored the heterogeneity in long-term depression change trajectories, and examined their correlates, particularly insomnia-related characteristics. METHOD:Participants were 148 adults (age M ± SD = 46.6 ± 12.6, 73.0% female) with insomnia and MDD who received antidepressant pharmacotherapy, and were randomized to 7-session Cognitive Behavioral Therapy for Insomnia or control conditions over 16 weeks with 2-year follow-ups. Depression and insomnia severity were assessed at baseline, biweekly during treatment, and every 4 months thereafter. Sleep effort and beliefs about sleep were also assessed. RESULTS:Growth mixture modeling revealed three trajectories: (a) Partial-Responders (68.9%) had moderate symptom reduction during early treatment (p value < .001) and maintained mild depression during follow-ups. (b) Initial-Responders (17.6%) had marked symptom reduction during treatment (p values < .001) and low depression severity at posttreatment, but increased severity over follow-up (p value < .001). (c) Optimal-Responders (13.5%) achieved most gains during early treatment (p value < .001), continued to improve (p value < .01) and maintained minimal depression during follow-ups. The classes did not differ significantly on baseline measures or treatment received, but differed on insomnia-related measures after treatment began (p values < .05): Optimal-Responders consistently endorsed the lowest insomnia severity, sleep effort, and unhelpful beliefs about sleep. CONCLUSIONS:Three depression symptom trajectories were observed among patients with comorbid insomnia and MDD. These trajectories were associated with insomnia-related constructs after commencing treatment. Early changes in insomnia characteristics may predict long-term depression outcomes. (PsycINFO Database Record

Study objectives

We previously presented results from a randomized controlled trial that examined the effects of antidepressant medication plus cognitive behavioral therapy for insomnia (CBT-I) among patients with major depressive disorder (MDD) and insomnia. The current secondary analysis aims to examine whether circadian preference moderated the reduction in depression and insomnia symptom severity during this trial.

Methods

A total of 139 adult participants with MDD and insomnia disorder were treated with antidepressant medication and randomized to receive 7 sessions of CBT-I or a control therapy (CTRL). Circadian preference (eveningness) was measured using the Composite Scale of Morningness (CSM). Depression symptom severity was assessed using the Hamilton Depression Rating Scale (HDRS); insomnia symptom severity was assessed using the Insomnia Severity Inventory (ISI). The moderating role of circadian preference on changes in HRSD and ISI was assessed via latent growth models within the framework of structural equation modeling.

Results

Greater evening preference was associated with smaller reduction in HDRS (P = .03) from baseline to week 6 across treatment groups. The interaction between CSM and treatment group was also significant (P = .02), indicating that participants with greater evening preference in the CTRL group had significantly smaller HDRS reduction than those with greater evening preference in the CBT-I group. Circadian preference did not share significant associations with ISI (all P > .30).

Conclusions

Individuals with MDD and insomnia who have an evening preference are at increased risk for poor response to pharmacological depression treatment augmented with either CBT-I or CTRL behavioral insomnia treatment. However, evening types have better depression outcomes when treated with CBT-I than with CTRL for insomnia.