Reduced Stress and Improved Sleep Quality Caused by Green Tea Are Associated with a Reduced Caffeine Content
Unno K, Noda S, Kawasaki Y, Yamada H, Morita A, Iguchi K, Nakamura Y
Nutrients · 50 citations
How it was studied
- Design
- Randomized controlled trial (indexed by PubMed)
- Studied in
- People
- Main outcome
- Health markers and function
Who paid for it
- Funding
- Independent funding
- Government
- Japan Society for the Promotion of Science
- Government
- Grant-in-Aid for Scientific Research
- University or hospital
- a grant for specially promoted research of the University of Shizuoka
- Grants
- Japan Society for the Promotion of Science (15K00828)
Based on 3 listed funder(s) and full-text disclosure statement.
Publication
- Published
- 2017-07-19 · Nutrients · vol. 9 · issue 7 · p. 777
- Publisher
- Multidisciplinary Digital Publishing Institute
- Cited
- 65 citations · more than 90% of similar papers · 2.6× the field average
- References
- 36 works
- Access
- Open access (journal) · CC-BY
- Research areas
- Tea Polyphenols and Effects · Tryptophan and brain disorders · Nutritional Studies and Diet
- Keywords
- Caffeine, Sleep quality, Sleep (system call), Green tea, Medicine, Food science, Chemistry, Pharmacology, Endocrinology, Insomnia, Computer science
- MeSH
- humans, catechin, caffeine, glutamates, cross-over studies, double-blind method, stress, psychological, sleep, tea, adult, middle aged, female, male, alpha-amylases
7 authors
From JP
- Keiko Unno · correspondingUniversity of Shizuoka
- Shigenori NodaUniversity of Shizuoka
- Yohei KawasakiUniversity of Shizuoka
- Hiroshi YamadaUniversity of Shizuoka
- Akio MoritaShizuoka University
- Kazuaki IguchiUniversity of Shizuoka
Abstract
Caffeine, one of the main components in green tea, can interfere with sleep and block the effect of theanine. Since theanine, the main amino acid in tea leaves, has significant anti-stress effects in animals and humans, we examined the effects of green tea with lowered caffeine content, i.e., low-caffeine green tea (LCGT), on stress and quality of sleep of middle-aged individuals (n = 20, mean age 51.3 ± 6.7 years) in a double-blind crossover design. Standard green tea (SGT) was used as the control. These teas (≥300 mL/day), which were eluted with room temperature water, were consumed over a period of seven days after a single washout term. The level of salivary α-amylase activity (sAA), a stress marker, was significantly lower in participants that consumed LCGT (64.7 U/mL) than in those that consumed SGT (73.9 U/mL). Sleep quality was higher in participants that consumed a larger quantity of LCGT. In addition, a self-diagnostic check for accumulated fatigue was significantly lower in those participants that consumed LCGT than SGT. These results indicate that LCGT intake can reduce stress in middle-aged individuals and improve their quality of sleep. The reduction in caffeine is suggested to be a valid reason for enhancing the anti-stress effect of green tea.
Abstract via Europe PMC. Copyright remains with the authors or publisher (CC BY).
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