Dose-Response Effects of Cognitive-Behavioral Insomnia Therapy: A Randomized Clinical Trial

SUBJECT OBJECTIVE: To determine the optimal number of therapist-guided Cognitive-Behavioral Insomnia Therapy (CBT) sessions required for treating primary sleep-maintenance insomnia. DESIGN AND SETTING: Randomized, parallel-group, clinical trial at a single academic medical center. Outpatient treatment lasted 8 weeks with final follow-up conducted at 6 months. PARTICIPANTS: 86 adults (43 women; mean age 55.4 +/- 9.7 years) with primary sleep-maintenance insomnia (nightly mean wake time after sleep onset WASO = 93.4 +/- 44.5 minutes). INTERVENTIONS: One (week 1), 2 (weeks 1 and 5), 4 (biweekly), or 8 (weekly) individual CBT sessions scheduled over an 8-week treatment phase, compared with an 8-week no-treatment waiting period (WL). MEASUREMENT: Sleep diary and actigraphy measures of total sleep time, onset latency, WASO, total wake time, and sleep efficiency, as well as questionnaire measures of global insomnia symptoms, sleep related self-efficacy, and mood. RESULTS: Statistical tests of subjective/objective sleep measures favored the 1- and 4-session CBT doses over the other CBT doses and WL control. However, comparisons of pretreatment data with data acquired at the 6-month follow-up showed only the 4-session group showed significant long-term improvements in objective wake time and sleep efficiency measures. Additionally, 58.3% of the patients receiving 4 CBT sessions met criteria for clinically significant improvement by the end of treatment compared to 43.8% of those receiving 1 CBT session, 22.2% of those provided 2 sessions, 35.3% of those receiving 8 sessions, and 9.1% of those in the control condition. CONCLUSION: Findings suggest that 4 individual, biweekly sessions represents the optimal dosing for the CBT intervention tested. Additional dose-response studies are warranted to test CBT models that contain additional treatment components or are delivered via group therapy.