Exploration of Relationships Between Sleep, Gut Health and Cognition

The Gut-sleep-brain Axis: Targeting the Gut Microbiota and Sleep Quality by Individualized Non-pharmaceutical Approaches to Promote Healthy Ageing.

Our study aims to build on emerging evidence showing relationships between gut health, sleep and brain functions. To achieve this, our study aims to test the feasibility of using non-pharmacological interventions: a psychoeducation-based intervention (enhanced sleep education - ESE) and a dietary supplement (Saffron extract), to improve sleep in older adults with insomnia complaints. Our study also aims to test the feasibility of using wearable and commercially available EEG headband technology to measure objective sleep quality in the home, which will allow for a reliable and ecologically more valid sleep research.

One-third of the UK adult population presents with disordered sleep, and the prevalence further increases with ageing. Disordered sleep has also been identified as a risk factor for dementia, which is alarming given that cases of dementia are predicted to triple across the world by 2050.

Our study aims to build on emerging evidence showing relationships between gut health, sleep, and brain functions. To achieve this, our study aims to test the feasibility of using non-pharmacological interventions: a psychoeducation-based intervention (enhanced sleep education - ESE) and a dietary supplement (Saffron extract), to improve sleep in older adults with insomnia. The study aims to test the feasibility of using wearable sleep tracking EEG technology (DREEM3 device) to measure sleep quality in the home environment, which could contribute to a reliable but naturalistic and accessible future sleep research.

The study is split into 4 phases:

Screening phase: Participants will be asked to complete an online screening assessment to check for eligibility.

Baseline assessment phase (1 week): Participants will complete in-person testing in the Sleep and Brain Research Unit (SBRU) located at the University of East Anglia, to assess their cognitive functions, psychological well-being, and postural control. They will be asked to provide a faecal sample to profile the baseline gut microbiota, a urine sample to gain a baseline measure for testing supplement adherence and wear the DREEM3 headband device and complete a sleep diary to track their sleep quality with a high accuracy in their habitual home environment.

Intervention phase (4 weeks): Participants will be randomly assigned to 1 of 4 groups following a factorial design: Group 1: Food supplement & ESE; Group 2: Food supplement & No ESE (control); Group 3: Placebo (control) & ESE, and Group 4: Placebo (control) & No ESE (control). These groups will allow us to test the effectiveness of each non-pharmacological intervention for feasibility.

Follow-up assessment (1 week - overlap with the last week of intervention): Participants will be asked to measure their sleep at home using the DREEM3 EEG device and complete a sleep diary, and finally will be re-tested for cognitive performance, psychological wellbeing, and postural control. A follow-up faecal sample and urine sample will be collected as well.

This research predicts that it is feasible for sleep difficulties in older adults to be objectively assessed in the home environment and non-pharmacologically treated using food supplements and behavioural techniques. It endeavours to provide pilot evidence for the effectiveness of future individualized non-pharmaceutical sleep treatments in older people at risk of dementia.

Inclusion Criteria:

1. Aged over 55 years
2. Conversational English and capacity to consent
3. Availability to take part in the study
4. Subjective sleep complaints of impaired sleep quality or insufficient sleep
5. Participants with no clinical diagnosis or signs of dementia (m-ACE-III score above 21)
6. Potential for sleep complications such as insomnia before the study
7. A body mass index between 20 and 35 for men, and 18.5 and 35 for women
8. High Score on Pittsburgh Sleep Quality Index (PSQI; > 5) OR The Insomnia Severity Index (ISI; > 10)

Exclusion Criteria:

1. Acute infections or diseases
2. Psychiatric disorders or chronic neurological conditions include a diagnosis of dementia, mild cognitive impairment (MCI)/ prodromal AD.
3. Learning, sensory, or motor impairment/ disabilities that would pose an unfair disadvantage in the cognitive tests
4. Chronic pain conditions
5. Currently taking blood thinning medications
6. Current diagnosis of malignant tumours/ cancers
7. Worked as a shift worker or travelled across more than three time zones in the past two months
8. Alcohol consumption above 14 units/week and/ use or dependency of illicit substances/alcohol
9. Consume more than 5 cups of caffeinated beverages (e.g., coffee/tea/coke, etc) per day.
10. Smokers (tobacco, e-cigarettes, or vapes)
11. Taking antibiotics, or any dietary supplements that may interfere with study outcomes.
12. Self-quarantined or presumed positive status for COVID-19 (see considerations for COVID-19 in safety and comfort section).
13. Currently enrolled or enrolled previously (within the last 2 months) in a drug trial.
14. Participants who show signs or symptoms of having dementia.
15. Participants with high scores (>10) on the Patient Heath Questionnaire-9 (PHQ-9) depression scale and/ or who indicate that they have suicidal thoughts
16. A diagnosis of untreated sleep apnoea or another sleep-related disorder excluding insomnia