Risk of excessive sleepiness in sleep restriction therapy and cognitive behavioral therapy for insomnia: a randomized controlled trial

Study Objectives: Sleep restriction therapy (SRT) has been shown to be comparably effective relative to cognitive behavioral therapy for insomnia (CBT-I), but with lower requirements for patient contact. As such, SRT appears to be a viable alternate treatment for those who cannot complete a full course of CBT-I. However, it is unclear whether SRT-a treatment solely focusing on restricting time in bed-increases risk for sleepiness comparably to CBT-I. The current study tested objective sleepiness as an outcome in a randomized controlled trial comparing SRT, CBT-I, and attention control in a sample of postmenopausal women in whom insomnia was diagnosed according to criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Methods: Single-site, randomized controlled trial. A total of 150 postmenopausal women (56.44 +/- 5.64 years) with perimenopausal or postmenopausal onset of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition insomnia disorder were randomized to 3 treatment conditions: sleep education control (6 sessions); SRT (2 sessions with interim phone contact); and CBT-I (6 sessions). Blinded assessments were performed at pretreatment and posttreatment. Risk of excessive sleepiness was evaluated using a symmetry analysis of sleepiness measured through the Multiple Sleep Latency Test (MSLT). Results: The odds ratios (ORs) of being excessively sleepy versus nonsleepy were not different than 1.0 for both SRT (OR = 0.94, 95% confidence interval [0.13-6.96]) and CBT-I (OR = 0.62, 95% confidence interval [0.09-4.46]), indicating that the odds of becoming excessively sleepy following treatment was not different from the odds of being nonsleepy. This suggests that excessive sleepiness is not of unique concern following SRT relative to CBT-I or sleep education. Conclusions: SRT appears to have a comparable risk profile for excessive sleepiness as CBT-I, and thus may be considered a safe alternative to CBT-I. Future research should characterize objective measures of excessive sleepiness immediately following sleep restriction.