STUDY OBJECTIVES: Patients with comorbid insomnia and sleep apnea (COMISA) report increased severity of depression, anxiety, and stress symptoms compared to patients with either insomnia or sleep apnea alone. Although cognitive behavioral therapy for insomnia (CBTi) is an effective treatment for COMISA, previous research suggests a reduced response to CBTi by patients with insomnia and depression, anxiety, and stress symptoms. Therefore, we used randomized controlled trial data to investigate the impact of depression, anxiety, and stress symptoms before treatment on changes in insomnia after CBTi vs control in patients with COMISA.
METHODS: 145 patients with COMISA (insomnia as defined by the International Classification of Sleep Disorders, third edition and apnea-hypopnea index ≥ 15 events/h) were randomized to CBTi (n = 72) or no-treatment control (n = 73). One-week sleep diaries and standardized questionnaire measures of insomnia, sleepiness, fatigue, depression, anxiety, and stress were completed pretreatment and posttreatment. Mixed models were used to examine interactions between depression, anxiety, and stress symptoms before treatment, intervention-group (CBTi, control), and time (pretreatment, posttreatment) on insomnia symptoms.
RESULTS: Approximately half of this COMISA sample reported at least mild symptoms of depression (57%), anxiety (53%), and stress (48%) before treatment. Patients reporting greater depression, anxiety, and stress symptoms before treatment also reported increased severity of insomnia, daytime fatigue, and sleepiness. Improvements in questionnaire and diary-measured insomnia symptoms improved during CBTi and were not moderated by severity of depression, anxiety, or stress symptoms before treatment (all interaction P ≥ .11).
CONCLUSIONS: We found no evidence that symptoms of depression, anxiety, or stress impair the effectiveness of CBTi in improving insomnia symptoms in patients with COMISA. Patients with COMISA and comorbid symptoms of depression, anxiety, and stress should be referred for CBTi to treat insomnia and improve subsequent management of their obstructive sleep apnea.
CLINICAL TRIAL REGISTRATION: Registry: Australian New Zealand Clinical Trials Registry; Name: Treating comorbid insomnia with obstructive sleep apnea (COMISA) study: A new treatment strategy for patients with combined insomnia and sleep apnea; URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=365184; Identifier: ACTRN12613001178730.
