1 Sleep, Cognition and Neuroimaging Lab, Department of Health, Kinesiology and Applied Physiology, School of Health & Center for Studies in Behavioural Neurobiology, Concordia University, Montreal, Quebec, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'Ile-de-Montréal, Québec, Canada. Electronic address: loicbrb@gmail.com.
2 Sleep, Cognition and Neuroimaging Lab, Department of Health, Kinesiology and Applied Physiology, School of Health & Center for Studies in Behavioural Neurobiology, Concordia University, Montreal, Quebec, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'Ile-de-Montréal, Québec, Canada; School of Psychology, University of Sydney, NSW, Australia.
3 Sleep, Cognition and Neuroimaging Lab, Department of Health, Kinesiology and Applied Physiology, School of Health & Center for Studies in Behavioural Neurobiology, Concordia University, Montreal, Quebec, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'Ile-de-Montréal, Québec, Canada; Sleep and Circadian Group, Woolcock Institute of Medical Research and Macquarie University, Sydney, NSW, Australia.
4 Sleep, Cognition and Neuroimaging Lab, Department of Health, Kinesiology and Applied Physiology, School of Health & Center for Studies in Behavioural Neurobiology, Concordia University, Montreal, Quebec, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'Ile-de-Montréal, Québec, Canada.
5 Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'Ile-de-Montréal, Québec, Canada.
6 Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'Ile-de-Montréal, Québec, Canada; Department of Psychology, University of Montreal, Quebec, Canada.
7 Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'Ile-de-Montréal, Québec, Canada; Stress, Interpersonal Relationship and Health Lab, Department of Psychology & Centre for Clinical Research in Health, Concordia University, Quebec, Canada.
8 Sleep, Cognition and Neuroimaging Lab, Department of Health, Kinesiology and Applied Physiology, School of Health & Center for Studies in Behavioural Neurobiology, Concordia University, Montreal, Quebec, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, CIUSSS Centre-Sud-de-l'Ile-de-Montréal, Québec, Canada. Electronic address: tt.dangvu@concordia.ca.

Objectives: Our objective was to assess the effect of cognitive-behavioral therapy for insomnia (CBTi) on subjective and objective sleep quality (including sleep spindles) and cognition during a sedative-hypnotics withdrawal program in older adults with insomnia disorder.

Methods: We performed a two-arm randomized controlled trial (RCT) of a sedative-hypnotic withdrawal plan alone (WPo group) or combined with CBTi (WP + CBTi group) in 47 older adults with insomnia disorder over a sixteen-week period. Our primary outcomes were change in self-reported insomnia severity (Insomnia Severity Index (ISI)), sleep efficiency (SE) from sleep diaries, and change in SE and spindle density from polysomnographic (PSG) recordings collected at baseline and at post-intervention (16 weeks). Secondary outcomes included other sleep changes from PSG, actigraphy and sleep diaries, sleep and mood questionnaires and neuropsychological assessments (manual dexterity, attention/concentration, verbal inhibition, visuo-spatial abilities).

Results: The withdrawal program was effective in achieving discontinuation and reducing insomnia severity, with similar success with and without CBTi. The combined intervention additionally improved subjective sleep quality and prevented the decrease in subjective sleep duration induced by sedative-hypnotic discontinuation. Neither intervention significantly impacted objective sleep architecture or cognitive performance. Furthermore, reduction in sleep spindle density was observed with combined CBTi and withdrawal, but not with withdrawal alone.

Conclusions: Both withdrawal alone and sedative-hypnotic withdrawal combined with CBTi effectively facilitated discontinuation and reduced insomnia severity, with the combined intervention further enhancing subjective sleep quality and preserving sleep duration. Although neither approach significantly impacted objective sleep architecture or cognitive performance, the potential reduction in sleep spindle density linked to the combined intervention warrants further investigation.