Objective sleep duration and response to combined pharmacotherapy and cognitive behavioral insomnia therapy among patients with comorbid depression and insomnia: a report from the TRIAD study.

STUDY OBJECTIVES: Several studies have shown that patients with short sleep duration show a poor response to cognitive behavioral therapy for insomnia (CBT-I) but such studies have not included patients with comorbid conditions. The current study was conducted to determine whether pre-treatment sleep duration moderates the response of patients with major depression (MDD) and insomnia (ID) disorders to a combined CBT-I and antidepressant medication treatment.

METHODS: This study comprised a secondary analysis of a larger randomized trial that tested combined CBT-I/antidepressant medication treatment of patients with MDD and ID. Participants (N=99; 70 women; Mage = 47.712.4 yrs.) completed pre-treatment polysomnography and then were randomly assigned to a 12-week treatment with antidepressant medication combined with CBT-I or a sham therapy (CTRL). Short and longer sleepers were defined using total sleep time cutoffs of <5, <6 and <7 hours for short sleep. Insomnia and depression remission ascertained respectively from the Insomnia Severity Index and Hamilton Rating Scale for Depression were used to compare treatment responses of short and longer sleepers defined by the cutoffs mentioned.

RESULTS: Logistic regression analyses showed that statistically significant results were obtained only when the cutoff of <5 hours of sleep was used to define "short sleep." Both the CBT-I recipients with < 5 hours of sleep (OR = 0.053; 95% CI = 0.006 - 0.499) and the CTRL group with ≥ 5 hours of sleep (OR = 0.149; 95% CI = 0.045 - 0.493) were significantly less likely to achieve insomnia remission than were CBT-I recipients with ≥ 5 hours of sleep. The shorter sleeping CBT-I group (OR = 0.118; 95% CI = 0.020 - 0.714) and longer sleeping CTRL group (OR = 0.321; 95% CI = 0.105 - 0.983) were also less likely to achieve insomnia and/or depression remission than was the longer sleeping CBT-I group with ≥ 5 hours of sleep.

CONCLUSIONS: Sleeping <5 hours may dispose comorbid MDD/ID patients to a poor response to combined CBT-I/medication treatments for their insomnia and depression. Future studies to replicate these findings and explore mechanisms of treatment response seem warranted.

CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Title: Treatment of Insomnia and Depression (TRIAD); Identifier: NCT00767624; URL: https://clinicaltrials.gov/ct2/show/results/NCT00767624.