• Alexander Sweetman, R Doug McEvoy, Simon Smith, Peter G Catcheside, Nick A Antic, Ching Li Chai-Coetzer, James Douglas, Amanda O'Grady, Nicola Dunn, Jan Robinson, Denzil Paul, Paul Williamson, and Leon Lack.
• Adelaide Institute for Sleep Health: A Centre of Research Excellence, College of Medicine and Public Health, Flinders University, Bedford Park, Australia.
• Sleep. 2020 Jul 13; 43 (7).

Study ObjectivesWhile cognitive and behavioral therapy for insomnia (CBTi) is an effective treatment in patients with comorbid moderate and severe obstructive sleep apnea (OSA), there is concern that the bedtime restriction component of CBTi might dangerously exacerbate daytime sleepiness in such patients. We examined randomized controlled trial data to investigate the effect of OSA severity, and pretreatment daytime sleepiness on week-to-week changes in daytime sleepiness and sleep parameters during CBTi and no-treatment control.MethodsOne hundred and forty-five patients with untreated physician-diagnosed OSA (apnea-hypopnea index ≥15) and psychologist-diagnosed insomnia (ICSD-3) were randomized to a 4-week CBTi program (n = 72) or no-treatment control (n = 73). The Epworth sleepiness scale (ESS) and sleep diaries were completed during pretreatment, weekly CBTi sessions, and posttreatment. Effects of OSA severity, pretreatment daytime sleepiness, and intervention group on weekly changes in daytime sleepiness and sleep parameters were investigated.ResultsThe CBTi group reported a 15% increase in ESS scores following the first week of bedtime restriction (M change = 1.3 points, 95% CI = 0.1-2.5, p = 0.031, Cohen's d = 0.27) which immediately returned to pretreatment levels for all subsequent weeks, while sleep parameters gradually improved throughout CBTi. There were no differences in changes in daytime sleepiness during treatment between CBTi and control groups or OSA-severity groups. Higher pretreatment ESS scores were associated with a greater ESS reduction during CBTi.ConclusionsCBTi appears to be a safe and effective treatment in the presence of comorbid moderate and severe OSA. Nevertheless, patients living with comorbid insomnia and sleep apnea and treated with CBTi should be monitored closely for increased daytime sleepiness during the initial weeks of bedtime restriction therapy.Clinical Trial RegistrationTreating comorbid insomnia with obstructive sleep apnoea (COMISA) study: A new treatment strategy for patients with combined insomnia and sleep apnoea, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id = 365184 Australian New Zealand Clinical Trials Registry: ACTRN12613001178730. Universal Trial Number: U1111-1149-4230.© Sleep Research Society 2020. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

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