The purpose of this study is to assess the feasibility of conducting a definitive randomised controlled trial that will determine the effectiveness of a digital cognitive behavioural therapy for insomnia intervention (Sleepio) in improving sleep, psychosocial health and cognitive performance in people with Mild Cognitive Impairment or mild dementia and co-morbid sleep disturbance.

Sleep is essential to maintain good physical and mental health and plays a central role in many physiological functions. Nevertheless, insomnia is common with approximately one-third of all adults experiencing insomnia symptoms, increasing to 75% in those aged over 65 years. Two recent meta-analyses suggest that insomnia increases the risk of developing dementia.

Cognitive behavioural therapy for insomnia (CBT-I) is the first-line treatment recommended for insomnia and is supported by a large evidence base. Unfortunately, however, CBT-I is often difficult to access due to the shortage of trained therapists. Digital CBT-I (dCBT-I) provides a possible solution to overcome the barriers associated with accessing the traditional therapist-delivered model of CBT-I. There is good evidence regarding the effectiveness of dCBT-I, which has also recently been shown to be feasible and effective in older people. A small mixed-methods study involving 12 participants has demonstrated preliminary acceptability of dCBT-I among older people with Mild Cognitive Impairment (MCI).

Sleepio is a dCBT-I programme that is specifically recommended as first-line treatment for insomnia by the National Institute for Health and Care Excellence (NICE). Underlying algorithms organise the delivery of evidence-based cognitive and behavioural techniques in a manner tailored to each individual based on their responses to an initial sleep study questionnaire and subsequent sleep diary entries throughout the duration of the programme. The Sleepio programme consists of six sessions. The programme can be completed within a six-week period. However, the average time taken to complete the programme is 9-10 weeks.

The investigators aim to conduct a randomised controlled feasibility study of this NICE-recommended dCBT-I intervention in participants with MCI and mild dementia.

Study participants will be community-dwelling adults aged fifty years and older with insomnia and established MCI or mild dementia. All patients attending outpatient memory clinics affiliated with the Mercy University Hospital in Cork City in the south of Ireland will be screened for eligibility. Consecutive patients who meet eligibility criteria will be invited to participate in the study. Where possible, study partners, being close friends or family members of study participants, will be recruited to support participants throughout the study.

Fully informed written consent will be obtained from each participant prior to enrolling them in the study. All participants will be determined able to provide informed written consent as adjudged by a consultant physician in geriatric medicine. Consent will also be obtained from their respective study partners (caregivers/friends/family members) if available and willing to participate.

Participants will be randomised to intervention versus true wait-list control in a 1:1 ratio using a centrally administered, computer-generated randomisation scheme. The study co-ordinator will be unblinded to study group assignment in order to facilitate provision of training regarding use of the intervention to those participants allocated to the intervention group. Site investigators, data collectors and statisticians will remain blinded to study group allocation.

At baseline, upon enrolment in the study, all participants will undergo assessments of their sleep, psychosocial health, cognition and function. These assessments will be repeated at follow up after 10 weeks.

This randomised controlled feasibility study will analyse the feasibility, acceptability and preliminary efficacy of a dCBT-I intervention to improve sleep, psychosocial health and cognitive function in participants with MCI and mild dementia. If shown to be feasible, the results will inform the design of a future definitive randomised controlled trial of the intervention in this population.

Inclusion Criteria:

1. Age ≥50 years.

2. Sleep Condition Indicator Score ≤16/32.

3. Established Mild Cognitive Impairment (MCI) or mild dementia, diagnosed by a consultant physician specialised in cognitive disorders prior to enrolment in the study. Dementia will be defined using DSM-5 classification and staged according to the Reisberg FAST scale into early/mild stage (Stages 1-4). MCI will be defined using Petersen's criteria. To participate those with MCI/mild dementia must score:

   1. ≥18 on the Mini-Mental State Examination (MMSE), and
   2. ≥0.5-1.0 on the Clinical Dementia Rating (CDR) scale.

4. Internet access for the duration of the intervention (via computer/tablet/smartphone).

5. Sufficient physical/sensory (visual/hearing) capacity to use the intervention, as judged by the clinician/investigator.

6. English-speaker (intervention only available in English).

7. Community-dwellers (non-institutionalised).

Exclusion Criteria:

1. Known history of an International Classification of Diseases (ICD) defined sleep disorder other than insomnia disorder.

2. Receipt of a sleep-related cognitive behavioural therapy (CBT) intervention within the past six months.

3. MMSE score <18 at enrolment, to facilitate adherence and ensure recruitment of those with mild-stage disease.

4. Severe depression (defined as depression requiring hospitalisation in the past 12-months or visit to psychiatry outpatient clinic in the past 3 months).

5. Unstable depression/anxiety disorders or panic attacks (unstable will be defined as changes in antidepressant medications within the last 3 months, i.e. no start, stop or change in dose).

6. Other relevant major neuropsychiatric disorders, including schizophrenia, psychosis, mania, bipolar affective disorder, epilepsy or seizure disorder.

7. Ongoing substance or alcohol abuse.

8. Long-term physical or sensory impairment, pain or other medical condition which, in the opinion of the principal investigator, could impair participation for reasons other than cognitive impairment.

9. Planned surgery or hospitalisation during the study that could interfere with participation.

10. Medical conditions rendering the patient too unwell to continue to participate in the study in the opinion of the principal investigator.

11. A change in the following medication within the three months prior to enrolment:

    1. Benzodiazepine and non-benzodiazepine hypnotic or anxiolytics agents
    2. Cholinesterase inhibitors or Memantine
    3. Antidepressants
    4. Antipsychotics
    5. Amphetamine derivatives
    6. Decongestants (pseudoephedrine, phenylephrine, phenyl¬propanolamine)
    7. Narcotic analgesics
    8. β-Blockers
    9. Pulmonary medications (theophylline and albuterol)
    10. Melatonin