Effects of Milk-based Drinks on Gut Microbiome, Sleep and Cardiometabolic Markers

The purpose of this study is to evaluate the effects of kefir on gastrointestinal health, sleep quality, and biochemical parameters in adults who have sleep problems. Further measurements of cognitive function, arterial stiffness and blood pressure will also be assessed. The following questions will be addressed during the study: 1. What effect does repeated ingestion of kefir have on the gut microbiome and can this positively influence sleep performance (quality and duration) in adults with sleep problems? 2. Does repeated ingestion of kefir impact LDL, triacyglycerols and non-HDLc in adults with sleep problems? 3. What effect does repeated ingestion of kefir have on cognitive function and mood? 4. What effect does repeated ingestion of kefir have on vascular function, inflammation and markers of immunity in adults with sleep problems? In a randomised, crossover design study, participants will consume 250 ml of kefir (original flavour) or milk for 4 weeks with a 4-week washout.

NCT Number	NCT07071181
Lead Sponsor	Sheffield Hallam University Collaborators: Biotiful, University of Leeds, Nimble Science Ltd.
Conditions	Sleep, Cardiovascular Diseases, Gut Microbiome, Cognitive Function and Mood, LDL Cholesterol
Enrollment	40 participants
Start Date	2025-08
Primary Completion	2026-03 (estimated)
Study Completion	2026-03 (estimated)
Updated on ClinicalTrials.gov	2025-07-17