Night-To-Night Sleep Variability in Older Adults with Chronic Insomnia: A Randomized Controlled Trial of Brief Behavioral Therapy for Insomnia

Introduction: Night-to-night variability in sleep is a clinical feature in understanding and treating insomnia in older adults. The present study examined changes in sleep variability in the course of a brief behavioral treatment for insomnia (BBT-I) in older adults who had chronic insomnia. Additionally, the present study examined the mediating mechanisms underlying reductions of sleep variability and the moderating effects of baseline sleep variability on treatment responsiveness. Methods: Sixty-two elderly participants were randomly assigned to either BBT-I or waitlist control (WLC). Sleep was assessed by sleep diaries and actigraphy from baseline to posttreatment and at 3-month follow-up. Mixed models were used to examine changes in sleep variability (within-person standard deviations of weekly sleep parameters) and the hypothesized mediation and moderation effects. Results: Variability in diary-assessed sleep onset latency (SOL) and actigraphy-assessed total sleep time (TST) significantly decreased in BBT-I compared to WLC (Pseudo R2=.12, .27; p=.018, .008). These effects were mediated by reductions in bedtime and wake time variability and time in bed. Significant time by group by baseline sleep variability interactions on sleep outcomes indicated that participants who had higher baseline sleep variability were more responsive to BBT-I; their actigraphy-assessed TST, SOL, and sleep efficiency improved to a greater degree (Pseudo R2=.15-.66; p\u3c.001-.044). Conclusion: BBT-I is effective in reducing sleep variability in older adults who have chronic insomnia. Increased consistency in bedtime and wake time and decreased time in bed mediate reductions of sleep variability. Baseline sleep variability may serve as a marker of greater treatment responsiveness to BBT-I. Support (If Any): The project described was supported by Award Number AG024459 (Christina S. McCrae, Ph.D., PI) from the National Institute on Aging (NIA). Additional support was provided by an Institutional Training Grant Award Number AG020499 (Michael Marsiske, PhD, Director) from the NIA