The recommended first-line treatment for insomnia is cognitive behavioral therapy for insomnia (CBTi), but access is limited. Telehealth- or internet-delivered CBTi are alternative ways to increase access. To date, these intervention modalities have never been compared within a single study. Further, few studies have examined a) predictors of response to the different modalities, b) whether successfully treating insomnia can result in improvement of health-related biomarkers, and c) mechanisms of change in CBTi. This protocol was designed to compare the three CBTi modalities to each other and a waitlist control for adults aged 50-65 years (N = 100). Participants are randomly assigned to one of four study arms: in-person- (n=30), telehealth- (n=30) internet-delivered (n=30) CBTi, or 12-week waitlist control (n=10). Outcomes include self-reported insomnia symptom severity, polysomnography, circadian rhythms of activity and core body temperature, blood- and sweat-based biomarkers, cognitive functioning, and magnetic resonance imaging.
