The Effects of Insomnia Treatment on Overnight Regulation of Emotional Memories and Risk for Mental Disorders

This project aims to understand and treat insomnia disorder to prevent depression and anxiety. The investigators will use an experimental parallel two-arm repeated measures randomized controlled trial in a cohort of individuals with insomnia to compare the effects of online therapist-guided cognitive behavioural and circadian therapy for insomnia (CBCTi; N=82) versus control (N=27) on subjective and objective sleep and circadian measures as well as symptom and severity of depression and anxiety. The project will involve at-home assessments.Participants from the CBCTi group will also be invited for two sleep studies and neuroimaging sessions to investigate the effects of CBCTi on neuroimaging and psychophysiological markers of overnight regulation of emotional distress.

This study is a parallel-group randomized controlled trial comparing the effects of online therapist-guided cognitive behavioural and circadian therapy for insomnia (CBCTi) versus control on emotional regulation and risk for mental disorders.

To be enrolled in the study, the participants are required to complete an online prescreening survey followed by a telephone screening interview with further questions and to verbally explain to participants what is required of them in this study. After an interview screening, the participants will receive a finger-pulse oximeter by mail to screen for the presence of obstructive sleep apnoea (3 nights at-home). The device is then returned by pre-paid mail and the recording is analysed to screen for moderate to severe sleep apnoea (oxygen desaturation index ≥ 10). If eligible, the participant will be invited to the Woolcock Institute for a screening visit.

The screening visit starts with a consult with a clinician/physician who performs a medical screening, explains the study, answers questions and addresses concerns, and obtains written informed consent. At the end of the consult, all eligibility criteria have been evaluated and eligible participants are assigned a randomization number i.e., allocated to either the CBCTi-arm or the control-arm. The treatment arm consists of an online therapist-guided CBCTi intervention which comprises online sessions to be completed in 8 weeks. The control arm in this study will consist of providing general sleep health information and access to daily sleep diaries.

During the screening visit, participants assigned to the CBCTi-arm will be asked to perform in an audio-visual recording while singing along to "Waltzing Matilda" (karaoke style) and asked to give keywords that relate to at least five negative distressing experiences and an equal number of neutral experiences from the same period. The recording and the keywords will be used to derive the stimuli that are used in the functional MRI tasks (T1 and T2). For both groups, the screening visit is concluded with a demonstration on how to collect data at-home.

Both groups will be asked to perform a week of at-home assessment during 4 timepoints: T1 (baseline), T2 (8-weeks post-baseline), T3 (8 months post-baseline) and T4 (20 months post-baseline). During the week of at-home assessments, the participants complete questionnaires, keep a sleep diary, and wear an actigraphy-watch, and light and temperature sensor (across 7 days). They are also asked to complete at least four overnight polysomnographic recordings. At T1 and T2 only, they also complete a salivary melatonin collection protocol.

Only the participants in the CBCTi arm complete additional in-lab assessments at T1 and T2. They are invited to Macquarie University/Woolcock Institute to undergo overnight sleep studies and neuroimaging sessions.

The CBCTi program will be given online via secure platforms and recruitment will primarily be through social media advertisements. The study will be coordinated from the Woolcock Institute of Medical Research, Sydney, Macquarie Park, New South Wales, 2109, Australia.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of insomnia disorder (DSM-V-TR) or ISI score ≥ 10.
* All sexes and genders.
* Between 25 and 45 years of age.
* Able to provide informed consent.
* Proficient in English.

Exclusion Criteria:

* Sleep or circadian disorder other than insomnia (e.g., hypersomnolence, periodic limb movement disorder, advanced or delayed sleep phase disorder, moderate to severe sleep apnoea disorder based on previous sleep study with an apnea-hypopnea index ≥ 15 and/or STOP-BANG high-risk score and/or finger-pulse oximetry oxygen desaturation index (ODI) ≥ 10).
* Any contradictions for MRI (e.g., claustrophobia, presence of metal in body, cochlear implants).
* Current or history of neurological disorders (e.g., stroke, brain injury).
* Current or history of any disorder listed in DSM-V other than major depression and anxiety disorders (post-traumatic stress disorder is excluded).
* Centrally active agents or presence of medical condition that may affect participation.
* Pregnancy or actively trying to conceive, or lactating.
* Shift work for at least 2 shifts per week in the past 3 months (i.e., work between 21:00 and 6:00).
* Travel across time zones over 3 hours difference in the previous 30 days (will require a 1-week adjustment period per hour of time zone travelled).
* Unwilling to know about potential incidental findings.
* No consent or adherence to instructions for any part of the study protocol.