The effect of cognitive and behavioral therapy for insomnia on week-to-week changes in sleepiness and sleep parameters in patients with comorbid insomnia and sleep apnea: a randomized controlled trial
STUDY OBJECTIVES: While cognitive and behavioral therapy for insomnia (CBTi) is an effective treatment in patients with co-morbid 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 pre-treatment daytime sleepiness on week-to-week changes in daytime sleepiness and sleep parameters during CBTi and no-treatment control. METHODS: 145 patients with untreated physician-diagnosed OSA (Apnea-hypopnea index>/=15) and psychologist-diagnosed insomnia (ICSD-3) were randomized to a four-week CBTi program (n=72), or no-treatment control (n=73). The Epworth sleepiness scale (ESS) and sleep diaries were completed during pre-treatment, weekly CBTi sessions, and post-treatment. Effects of OSA-severity, pre-treatment daytime sleepiness, and intervention-group, on weekly-changes in daytime sleepiness and sleep parameters were investigated. RESULTS: The 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 pre-treatment 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 pre-treatment ESS scores were associated with a greater ESS reduction during CBTi. CONCLUSION: CBTi appears to be a safe and effective treatment in the presence of co-morbid moderate and severe OSA. Nevertheless, COMISA patients treated with CBTi should be monitored closely for increased daytime sleepiness during the initial weeks of bedtime restriction therapy.