Sleep
L-theanineand Pittsburgh Sleep Quality Index (PSQI)
Only one source here so far, and it measured lower pittsburgh Sleep Quality Index (PSQI).
How sure anyone can be
Low certainty, level 2 of 4Further research is likely to change this.
The numbers reported
No number has been put on this yet. One source recorded only which way the numbers went — for now, that is all we have here.
One source, newest first
What we read is the published abstract, not the full paper, so a blank below may still be printed in the paper itself. A fixed rule worked this out from the source’s own fields. Nobody checked this rating by hand.
Randomised trial, 2019 · 30 participants
Low certainty, level 2 of 4Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial.
Nutrients. 2019;11(10). doi:10.3390/nu11102362. PMID:31623400.
- Number reported
- Not in the abstract
- Which way it went
- Lower
- Likely range
- Not in the abstract
- Source’s own words
- within-trial change in PSQI score; no effect size reported, p-value only
- Who was studied
- Adult
- Compared with
- none for this estimate - within-arm pre-post change during L-theanine administration in a placebo-controlled crossover trial
- Amount taken
- 200 mg/d
- For how long
- 28 days
- Disagreement between studies
- Not in the abstract
- Kind of record
- Journal article
How this rating was reachedstarts at High, 2 steps down: risk of bias and imprecision
- Starts at High
- Risk of bias brought it down to Moderatethe abstract reports no risk-of-bias or quality appraisal, so study limitations cannot be ruled outNot in the abstract
- Imprecision brought it down to Lowthe abstract reports no confidence interval for the estimateNot in the abstract
- Ends at Low2 steps down.
- Checked, nothing to step it down for
- indirectness
- Inconsistency
- One study, so there was nothing to disagree
Imprecision stops at the first check that applies; others may apply too.
AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.
What is still missing from these readings
- No number at all, only which way it went.
- One gives no likely range, so how precise that number is is unknown.
Something nobody wrote down is never a zero and never a guess.
Still to read for L-theanine
Five of the 12 things on our list for L-theanine have no reading here yet:
- Alpha EEG power
- Diastolic blood pressure
- Heart rate variability (RMSSD)
- Resting heart rate
- Systolic blood pressure
Still to read means nobody here has got to it, not that it was tried and did nothing or that no research exists. A pairing on no list is not a gap: we never set out to read it.
Read next
L-theanine
Six other questions read for it
Sleep
28 questions read under it
Pittsburgh Sleep Quality Index (PSQI)
One other ingredient read against it
Alphabetical, and by nothing else.
This is a library, not advice. No recommendation, no dose, no diagnosis, no ranking. We never ask about your symptoms, and nothing here is tailored to you.