The principal objective of the study is to assess the feasibility and preliminary efficacy of an online-delivered CBT-I intervention for those with insomnia or reporting sleep difficulties. The program will be offered to service users of IAPT to establish criteria for the planning of a future large scale RCT study.

Meta-analytic evidence have shown that internet-delivered CBT-I works at improving insomnia severity, sleep efficiency, subjective sleep quality, wake after sleep onset, sleep onset latency, total sleep time, and number of nocturnal awakenings at post-treatment (Zachariae et al., 2016). Furthermore, these interventions have also been shown efficacious in decreasing depressive symptoms (Christensen et al., 2016).

However, no studies have explored the effects of internet-delivered CBT-I in routine care settings and all of them recruited a self-selected sample, which limits the generalizability of the results. In this sense, the present study is a first step to assess the feasibility and preliminary efficacy of internet-delivered CBT-I in a real-world setting: the Improving Access to Psychological Therapies (IAPT) program, National Health service, England.

The IAPT program is part of a stepped care model that principally addresses depression and anxiety in the population (Clark, 2011). It sees over a million users per year and delivers both low-intensity (e.g. internet-delivered CBT for depression and anxiety disorders; group wellbeing courses, bibliography) and high-intensity (e.g. counseling for depression, face-to-face CBT for depression and anxiety) services (Clark, 2011).

Within IAPT, SilverCloud Health as a global leader in the development and implementation of internet-delivered interventions for mental health, wellbeing and long-term condition management, has supported patients at a low-intensity level (i.e. Step 2) over the past 5 years. SilverCloud has recently developed an intervention for insomnia that will form part of the overall mental health care suite of programs that include interventions for depression and anxiety disorders. The outcomes of these online interventions have been equal to other low-intensity interventions used within IAPT. The current study seeks to pilot the newly developed CBT-I intervention to assess its initial clinical impact and to establish criteria for the planning of a future large scale RCT study.

Objective As part of service evaluation, patients at Berkshire NHS Foundation trust availed of the Space for Sleep program. The current study seeks to carry out research on the progress of these patients, assessing the program's initial clinical impact and to establish criteria for the planning of a future large scale RCT study.

Specific research questions will be the following:

• Can Space for Sleep achieve positive clinical outcomes for patients?
• What are the levels of satisfaction and acceptance of users with the intervention?
• What are the levels of usage of the intervention?

Design Moving from service evaluation to an open feasibility trial design to examine the potential clinical impact of an online CBT intervention for insomnia disorder (ID).

Hypotheses SilverCloud online interventions for mental health have proved highly successful. The investigators anticipate that the current intervention for ID will show preliminary effectiveness at post-treatment in terms of greater sleep efficiency and significant reductions in symptoms of insomnia and co-morbid depression and anxiety.

Study Setting The study will be conducted within Berkshire Healthcare NHS Foundation Trust through Talking Therapies, an NHS IAPT provider that serves a population of 900,000 across 7 Clinical Commissioning Groups (CCGs), all of which are demographically and economically diverse, ranging from rural West Berkshire to urban commuter towns close to London. Talking Therapies aims to provide an easily accessible and clinically effective service for those within the community who suffer from sleep disorders. Those wishing to access the service can do so through self-referral, GP referral or referral from allied services. If suitable, clients are offered treatment either at Step 2 or Step 3 based on their need. Step 2 services include low-intensity CBT-based treatments such as self-help, iCBT and group treatment, supported by trained psychological wellbeing practitioners (PWP).

Recruitment procedures The aim is to recruit 35 patients as part of service evaluation. A 50% uplift is added to buffer against the effects of dropout/missing data. Therefore, a total of 52 participants will be included in the study. Patients who are already using the program as part of the service evaluation will be provided with an information sheet and asked if they wish to retrospective consent to for their data to be part of the research trial.

For those who will be recruited into the research, firstly, individuals are given an initial assessment by phone with a PWP clinician at Berkshire IAPT service as per normal service provision. The assessment determines if an individual meets the eligibility criteria and a diagnosis of sleep disorder will be advised by the PWP. The PWP then describes the trial and invites the client to participate. Those interested will receive an email with information detailing the study and a link to the consent form to give consent by means of a digital signature. Upon giving consent, participants complete the primary and secondary outcomes for the study online. PWPs will reiterate details of the research and the program, describing what is involved and the importance of their participation in the trial. Participants receive an email informing them on how to proceed.

All participants are informed that they are free to withdraw if they no longer wish to take part in the trial. In this case, they will be removed from the trial and they will be offered treatment as usual.

Support during treatment Each participant will be assigned a PWP clinician who will monitor participants' progress throughout the trial. Once assigned to the active treatment condition the participant will receive a message from their PWP clinician at their first login. This message welcomes them to the program, highlights aspects of the program, and encourages them in use of the program. Over the course of the 8-week supported intervention, on 6 separate occasions the PWP will login and review participants progress, leaving feedback for them and responding to the work they have completed. The basic share level allows supporters to view users' goals for the week; key messages and progress points. If users wish to share more with their supporter, they can share journal entries. Each supporter will provide post-session feedback of between 10 and 15 minutes per participant per session, over the eight-week intervention period.

Inclusion Criteria:

• At least 18 years old
• Reporting difficulty getting to sleep and/or staying asleep as their primary presentation
• Suitability for an internet intervention (i.e. willingness to engage on the iCBT intervention, ability to read English, access internet, the capacity and willingness to consent)
• No suicidal or self-harm risk and no specific communication needs.

Exclusion Criteria:

• Score above 0 on PHQ-9 question 9
• Diagnosed psychotic illness
• Currently on psychological or pharmacological treatment for sleep disorder
• Alcohol or drug misuse
• Previous diagnosis of an organic mental health disorder,
• Have an unstable medication regimen.