Understanding the Effects of Daily Tea Consumption on Attention, Sleep, and Mood, in Healthy Adults

Summary

The goal of these series of N-of-1 trials is to compare the effects of three tea interventions on cognition, mood, and sleep, in healthy adult participants. The main questions they aim to answer are:

* What are the short-term effects of, and differences between, three different black tea interventions on cognition, mood, and sleep, in individual participants?
* What are the short-term effects of, and differences between, three different green tea interventions on cognition, mood, and sleep, in individual participants?
* Are there any other lifestyle factors that influence the relationship between tea intake and cognition, mood, or sleep, and to what extent do they have an effect?

Participants will be asked to drink three different tea interventions in four blocks of three weeks, where each week is assigned one tea intervention. At regular intervals three times per day, seven days per week, for the 12-week study duration, participants will be asked to complete a sleep questionnaire, mood questionnaire, personalised questionnaire (with questions pertaining to physical activity and work, for example), a tea consumption recall questionnaire, and two cognitive tasks based on attention (lasting one minute each). These questionnaires and tasks comprise one measurement point and take approximately five to six minutes to complete.

Conditions

• The Focus of the Study is Healthy Volunteers

Interventions

OTHER

Black tea flavoured, tea drink

Black tea powder containing 50.0 mg of caffeine and 11.5 mg of theanine, to be dissolved in 200 ml boiling water.

OTHER

Black tea flavoured, caffeine-only drink

50.0 mg of caffeine in a black tea-like powder i.e., matched to the 'black tea' intervention for flavour and appearance, to be dissolved in 200 ml boiling water. Caffeine is the only biologically active ingredient in this intervention.

OTHER

Black tea flavoured, placebo drink

A black tea-like powder i.e., matched to the 'black tea' intervention for flavour and appearance, containing no biologically active ingredients, to be dissolved in 200 ml boiling water.

OTHER

Green tea flavoured, tea drink

Green tea powder containing 30.6 mg of caffeine and 11.1 mg of theanine, to be dissolved in 200 ml boiling water.

OTHER

Green tea flavoured, caffeine-only drink

30.6 mg of caffeine in a green tea-like powder i.e., matched to the 'green tea' intervention for flavour and appearance, to be dissolved in 200 ml boiling water. Caffeine is the only biologically active ingredient in this intervention.

OTHER

Green tea flavoured, placebo drink

A green tea-like powder i.e., matched to the 'green tea' intervention for flavour and appearance, containing no biologically active ingredients, to be dissolved in 200 ml boiling water.

Sponsors & Collaborators

• Lipton Teas and Infusions

  collaborator UNKNOWN

• University of Aberdeen

  lead OTHER

Principal Investigators

• Baukje d Roos, PhD · The Rowett Institute

Study Design

Allocation

NON_RANDOMIZED

Purpose

OTHER

Masking

QUADRUPLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2023-09-02

Primary Completion

2025-05-17

Completion

2025-05-17

Countries

• United Kingdom

Study Locations