The Effects of a Multi-ingredient Night-time Tea on Sleep Quality, Wellbeing and Markers of Immune Function

The aim of the study is to determine whether a night-time tea can improve subjective sleep quality in healthy sleepers and self-reported poor sleepers, compared to a control drink.

The study will adopt a randomised, double-blind, placebo controlled, crossover design. Sixty-eight healthy adults aged 18+ (34 good sleepers and 34 poor sleepers) will be recruited from the general population. Good sleepers will be recruited if they have a stable sleep-wake schedule (i.e. bed/wake time within the range of 22.00 - 09.00 and with at least 6.5 hours of sleep duration reported per night). Poor sleepers will be recruited if they report subjective sleep difficulties (i.e. poor sleep quality or unrefreshing sleep) and if they display a Pittsburgh Sleep Quality Index total score of \>5. Participants will consume both an active tea, and a control tea in a counterbalanced order for 7 days (separated by a 7-day washout period). Participants will complete questionnaires assessing mood, quality of life and sleep and provide blood samples to assess immunological markers. Sleep monitoring will also be conducted using actigraphy sleep monitoring and sleep diaries. Assessments will be made at baseline and following 7 days supplementation.