Theanine maintains sleep quality in healthy young women by suppressing the increase in caffeine-induced wakefulness after sleep onset.
Study Goal
The researchers aimed to determine whether theanine improves sleep quality in healthy young women when caffeine negatively affects it.
Results Summary
The study found that theanine suppressed caffeine-induced increases in wake after sleep onset (WASO) time, suggesting it mitigates caffeine's negative effects on sleep quality. No significant differences were observed in sleep-onset latency or number of WASOs between the theanine or combined theanine-caffeine groups and the placebo.
Population
Healthy young women
Effective Dosage
50 mg theanine, 30 mg caffeine
Duration
Not specified in the abstract
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
caffeine | increase | WASO time | healthy young women | - | showed a significant increase | #1 |
theanine | no change | WASO time | healthy young women | - | no difference was observed | #2 |
combined theanine and caffeine (TC) | no change | WASO time | healthy young women | - | no difference was observed | #3 |
theanine | no change | sleep-onset latency | healthy young women | - | no differences | #4 |
caffeine | no change | sleep-onset latency | healthy young women | - | no differences | #5 |
combined theanine and caffeine (TC) | no change | sleep-onset latency | healthy young women | - | no differences | #6 |
theanine | no change | number of WASOs | healthy young women | - | no differences | #7 |
caffeine | no change | number of WASOs | healthy young women | - | no differences | #8 |
combined theanine and caffeine (TC) | no change | number of WASOs | healthy young women | - | no differences | #9 |
theanine | decrease | caffeine-induced increase in the WASO time | healthy young women | - | suppressed | #10 |
theanine | decrease | caffeine's effects on sleep quality | - | - | can reduce | #11 |
Energy drinks take advantage of caffeine's effects on wakefulness and performance; however, excessive intake has a negative effect on sleep. Green tea is consumed worldwide and has both a stimulating effect from caffeine and a calming or relaxing effect from theanine. Theanine reduces the excitotoxicity of caffeine. This study evaluated whether theanine improves the sleep quality worsened by caffeine in healthy young women. Sleep latency, sleep time, wake after sleep onset (WASO) time, and the number of WASOs were measured. A crossover study was performed using four treatment groups: theanine (50 mg), caffeine (30 mg), combined theanine and caffeine (TC), and placebo. The sleep stage was determined using electroencephalograms, and cerebral blood flow was measured using near-infrared spectroscopy. The caffeine group showed a significant increase in the WASO time compared with the placebo group; no difference was observed between the theanine or TC group and the placebo group. There were no differences in the sleep-onset latency or number of WASOs between the theanine, caffeine, or TC groups and the placebo group. In combination with theanine, only the caffeine-induced increase in the WASO time was suppressed. Our results suggest that theanine can reduce caffeine's effects on sleep quality.