This will be a double-blind, placebo-controlled, parallel-group trial. Participants who are poor sleepers will be randomised to receive one of two investigational supplements, or a placebo control supplement, over a 28-day period. At baseline and following 28 days of consumption, sleep quality, gut microbiome profiles, cognitive performance, and mood will be assessed. Sleep outcome measures will also be assessed throughout the supplementation period to monitor the time course of any observed changes. A final data set of at least 66 participants is expected.
Interested participants will initially be scheduled to complete a screening telephone call with the researcher. Here, electronic informed consent will first be provided by the participant, by accessing a pre-emailed link to the Qualtrics survey platform, to an account which is hosted by Northumbria University. Once consent is obtained, the participant will confirm that they do not meet any of the study exclusion criteria, and will complete the SDS-CL checklist with the researcher, over the phone. If any clinical thresholds are met, participants will be invited to a separate clinical interview (again via phonecall) with Professor Jason Ellis, employing the International Classification of Sleep Disorders (ICSD-3) criteria, to determine elligibility.
If participants progress to enrolment, they will be invited to attend a lab-based training/screening session (protocol day -7) at Northumbria University. Here, hard and wet-signed (by both the participant and the researcher) consent forms will be completed and stored on site. Participants will then be familiarised with the study protocol and procedures. Participants will also be trained on the cognitive tasks. During the following 7 nights (Protocol days -7 to -1), participants will monitor their sleep and complete the daily Sleep Diary each morning. During this week, they will also drop off their pre-dose baseline stool sample at a remote drop-off location at Northumbria University.
Seven days following the lab-based screening visit (Supplement day 1, Protocol day 0), participants will attend the laboratory for their acute visit. Here, a pre-dose baseline sample of saliva and a single blood sample will be taken (for Alpha Amylase, Cortisol, Serotonin and Melatonin), and Blood Pressure, Heart Rate, Body Mass Index, and Waist-to-Hip Ratio will be measured. Participants will complete the Intake24 dietary assessment, and gastrointestinal symptoms questionnaires, as well as the Pittsburgh Sleep Quality Index (PSQI), State-Trait Anxiety Inventory (STAI), and Depression, Anxiety and Stress Scale - 21 Items (DASS-21). The cognitive task battery will additionally be completed.
After completing these measures, participants will receive instructions on the next phase of the trial. From that night, participants will consume their first dose of the investigational supplement (noting the time in their treatyment diary) 4 hours before their normal bed-time. They will monitor their sleep overnight. The following morning (supplementation day 2, protocol day 1), participants will complete their Sleep Diary. Participants will follow this procedure for the following 27 days. At some point during Protocol (Days 12-18), participants will return to Northumbria University to drop-off their interim stool sample.
On Protocol day 28, participants will return to the lab for the chronic testing visit. All of the outcome measures assessed during the acute lab visit (Protocol day 0) will be repeated here. At the end of the session, participants will be debriefed, and their participation payment arranged. At some point during Protocol (Days 27-33) participants will return to Northumbria University to drop-off their chronic stool sample.
