Sleep and cognition following digital cognitive behavioral therapy for insomnia (CBTi) - the SCOTIA study

INTERVENTION: Participants are block randomized (1:1) to one of two study arms. The sequence is generated using the website, www.sealedenvelope.com, and is stratified by sex (male/female) and age (25‐44/45‐65). Treatment group (dCBT): Participants receive digital Cognitive Behavioural Therapy (dCBT) delivered via the Sleepioâ„¢ programme. This comprises of six weekly 15‐20 sessions delivered by an animated virtual therapist. The Sleepio programme has been tested in multiple RCTs. Control group (WLC): Participants are placed on a waiting list for 8 weeks. During the 8‐week period both groups record a sleep diary and wear an actigraph watch. CONDITION: Insomnia disorder ; Mental and Behavioural Disorders ; Insomnia disorder PRIMARY OUTCOME: ; 1. Insomnia severity will be measured through the Sleep Condition Indicator; 2. Objective sleep efficiency will be measured with polysomnography (PSG) at baseline and post‐treatment.; INCLUSION CRITERIA: 1. Participant is willing and able to give informed consent for participation in the study 2. Male or Female, aged 25‐65 years 3. Screening positive for persistent insomnia disorder as indicated on the Sleep Condition Indicator 4. Average (over 7 nights) sleep onset latency of >30min and/or wake after sleep onset >30min (determined by actigraphy) 5. Typical sleep period takes place within the hours of 10pm – 9am 6. Can read and understand English 7. Regular access to the internet with a tablet, laptop or desktop computer 8. Normal or corrected to normal vision SECONDARY OUTCOME: ; 1. Objective sleep latency and sleep continuity will be measured through PSG and actigraphy (sleep onset latency, wake‐time after sleep onset, and number of awakenings) at baseline and post‐treatment.; 2. Objective sleep architecture will be measured through PSG [duration in each sleep stage and sleep fragmentation (stage change index)] at baseline and post‐treatment.; 3. Subjective sleep continuity will be measured through a sleep diary (sleep onset latency, wake‐time after sleep onset, number of awakenings, and sleep efficiency) at baseline and post‐treatment.; 4. Changes in EEG delta power and slow wave activity will be measured through whole night EEG spectral analysis (power in the delta frequency band and slow wave oscillation evaluations) at baseline and post‐treatment.; 5. Subjective and objective arousal will be measured through 1) questionnaires (Glasgow Content of Thoughts Inventory, the Sleep Interference Rating Scale and the Pre‐Sleep Arousal Scale) and 2) pre/post sleep resting state EEG (assessed by EEG spectral power in the high frequency range) at baseline and post‐treatment.; 6. Global sleep quality (Pittsburgh Sleep Quality Index), cognitive impairment (British Columbia Cognitive Complaints Inventory), fatigue (Flinders Fatigue Scale), worry (Penn State Worry Questionnaire), rumination (Ruminative Responses Scale), emotion regulation (Difficulties in Emotion Regulation), and sleep‐related quality of life (Glasgow Sleep Impact Index) will be measured at baseline and post‐treatment.; 7. Cognitive and emotional functioning will be measured using the Emotional Test Battery, word‐pair memory task, and attention task at baseline and post treatment.; 8. Inter‐daily stability and relative amplitude of rest‐activity rhythms (non‐parametric circadian rhythm analysis) will be measured with actigraphy during treatment phase.; 9. Objective‐subjective sleep discrepancy will be computed from sleep diary and PSG for the laboratory nights (baseline and post treatment) and for sleep diary and actigraphy (baseline and during treatment phase).; 10. Self‐reported adverse effects will be collected by questionnaire at mid‐treatment and end of treatment;