Baseline sleep characteristics are associated with gains in sleep duration after cognitive behavioral therapy for insomnia

Objective/background: Cognitive behavioural therapy for insomnia (CBT-I) substantially reduces total wake time (TWT) by the end of treatment. In contrast, total sleep time (TST) does not increase above baseline levels for most patients following 4–8 sessions of treatment. In the 6–12 months following CBT-I, without any further intervention, up to 64% of participants substantially increase their TST (by ≥ 30 min). The current study investigated which baseline characteristics are associated with increases in TST after CBT-I. Patients/methods: Data were analysed from a randomised controlled trial assessing acute and maintenance CBT-I (N = 80). Linear mixed models were conducted to assess the effect of baseline characteristics on changes in TST up to 24 months after CBT-I. Baseline characteristics included age, sex, marital status, sleep continuity (derived from sleep diaries and polysomnography studies), and mental health and quality of life questionnaires. Results: At baseline, self-reported sleep latency, wake after sleep onset, early morning awakenings, TWT, TST, and sleep efficiency were associated with the greatest changes in TST (p < .03 for interactions), such that patients who reported more wake/less sleep at baseline also reported the largest increases in TST. No other baseline variables were associated with changes in TST after CBT-I, including age, sex, and polysomnography-derived sleep continuity (p > .07 for interactions). Conclusions: Patients with more severe self-reported sleep difficulties and lower sleep duration at baseline showed greater improvements in TST after CBT-I. Whether more patients could increase their TST, within the context of acute treatment or following treatment, warrants investigation.