P084 Is Cognitive Behaviour Therapy for insomnia (CBTi) responsiveness a function of objective sleep efficiency rather than objective sleep duration?

INTRODUCTION: Past research and our own has not shown a differential response to Cognitive Behaviour Therapy for insomnia (CBTi) based on objective sleep duration. It is valuable to investigate CBTi responsiveness is a function of objective sleep efficiency (SE) instead of objective sleep duration. This study is a secondary exploratory analysis of our earlier clinical trial to assess the differential therapeutic response to CBTi for older insomniacs based on SE prior to treatment. METHOD: Seventy-nine adults (male=34, mean age=63.38, SD=6.25) with sleep maintenance insomnia were selected. Participants were grouped into 3 ordinal groups; the top 50% of participants (above the median percent sleep time-normal SE), the 25% of participants in the third quartile (moderately low SE), and the bottom 25% of participants (severely low SE) based on 1-night of home-based polysomnography. Participants were randomly allocated to CBTi or wait-list control. One-week sleep diaries, actigraphy and a battery of questionnaires evaluated the efficacy of CBTi for each SE group. Outcome measures were taken at pre-treatment, post-treatment, and 3-month follow-up. RESULTS: CBTi produced robust improvements in sleep quality including reduced wake after sleep onset, and improved sleep efficiency. Participants reported a reduction of scores on the Insomnia Severity Index, Flinders Fatigue Scale, Epworth Sleepiness Scale, Daytime Feeling and Functioning Scale, Sleep Anticipatory Anxiety Questionnaire, Dysfunctional Beliefs and Attitudes Scale, and increased Sleep Self-Efficacy Scale. All improvements were significant relative to waitlist and comparable regardless of objective SE at pre-treatment. DISCUSSION: CBTi responsiveness did not differ as a function of objective SE.