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.