an-exploratory-evaluation-of-a-low-dose-theanine-consumption-on-improving-sleep-in-middleaged-and-older-males-2037

1. Study Overview

  • Title: An Exploratory Evaluation of a Low Dose Theanine Consumption on Improving Sleep in Middle-Aged and Older Males

  • Authors: Tominaga T, Furushima D, Unno K, Sugiyama I, Ozeki M, Nakamura Y, Yamada H

  • Published in: Food Science & Nutrition Research, 2022

  • Study Objective: To explore the sleep-improving effects of a low dose (100 mg/day) of L-theanine among middle-aged and older males.

  • Methodology:

    • Type: Double-blind, randomized crossover study.

    • Participants: 25 middle-aged and older males, aged 40-65, with exclusion criteria for certain medications and lifestyle factors.

    • Interventions: Participants received either theanine or placebo for one week, followed by a washout period.

2. Background

  • L-Theanine:

    • Found in green tea, considered to have anti-anxiety and sleep-improving properties.

    • Consistent previous studies indicate efficacy at doses of 200-400 mg/day.

    • Lower doses may also yield benefits, as suggested by earlier trials involving lower caffeine green tea.

  • Psychological Stress: Identified as a major contributor to sleep disorders, highlighting the importance of stress-reduction methods prior to sleeping.

3. Methods

3.1 Participant Selection

  • Inclusion Criteria: Men aged 40-65, working weekdays.

  • Exclusion Criteria: Individuals on certain medications affecting sleep, smokers, and alcohol consumers during the study.

  • Consent: Participants provided written informed consent before inclusion.

3.2 Study Design

  • Group Assignment: Participants randomly divided into Group A and Group B (1:1 ratio).

  • Periods:

    • Period 1: No sample intake (baseline).

    • Period 2: Theanine or placebo.

    • Period 3: Washout.

    • Period 4: The opposing treatment to Period 2.

3.3 Data Collection

  • EEG Monitoring: Used to measure sleep parameters, including total sleep time, non-REM stages, REM, and awakenings.

  • Questionnaire: Subjective sleep quality rated on a scale after waking over five days.

4. Results

4.1 Participant Demographics

  • Sample Size: 25 enrolled (after dropouts, 19 analyzed).

  • Mean age: Group A - 46.2 years; Group B - 47.1 years.

4.2 Main Findings

  • Statistical Analysis: No significant differences in sleep parameters between the theanine and placebo periods (p > 0.05).

  • Notable trend: The percentage of non-REM sleep stage 2 (N2) in the theanine group showed a tendency to be higher than the placebo group (p = 0.053).

4.3 Subgroup Analysis

  • Age Influence: Participants under 50 years showed a statistically significant increase in N2 during the theanine period (p = 0.018).

  • Green Tea Habit: Those consuming green tea less frequently (<3-4 days/week) demonstrated significant improvement in N2 with theanine (p = 0.048).

5. Discussion

  • Implications: While the overall effect of 100 mg/day theanine on sleep improvement was not significant, certain demographic factors like age and green tea consumption impacted outcomes.

  • Physiological Role of N2: Involved in relaxation and may influence memory retention, highlighting the potential cognitive benefits of theanine.

  • Limitations: The study sample consisted solely of middle-aged and older men; results may not generalize to all populations. Other factors, such as caffeine consumption during the study, were uncontrolled.

6. Conclusions

  • Key Takeaway: Consumption of 100 mg/day of L-theanine does not significantly enhance sleep overall, but certain subgroups (younger participants and those with specific green tea habits) may benefit.

  • Future Research: Recommended to include women and younger populations to broaden understanding and explore effects of higher doses.