Key Findings
- Sleep quality scores decrease by 3 points
- 84% of participants improved by at least 1 point
- Nearly one-third no longer met criteria for sleep disturbance
- Wearable sleep recovery scores improved by week 4
- Sleeping heart rate decreased significantly in the first week
Overview of Methods
19 adults with self reported sleep problems and poor sleep scores over 6 were all given the same treatment:
- 700 mg/day GABA + 200 mg/day L-theanine once daily before bed for 4 weeks.
"Before supplement intake, all 19 patients had a score of ≥7, and 10 had a PSQI-J global score of ≥10."
Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI). The PSQI is scored from 0–21, with lower scores indicating better sleep quality and scores over 6 reflecting poor sleep.
Participants also wore a Fitbit Charge 5 to track sleep duration, heart rate during sleep, movement, and electrodermal activity.
Sleep Quality Significantly Improved
After 4 weeks, 84% of participants self-reported better sleep quality with overall PSQI scores dropping 3 points.
"16 of the 19 patients showed an improvement of ≥1 point… 31.6% had a score of ≤5, considered without sleep problems."
Before supplementation, all participants scored ≥7. After 4 weeks the average PSQI score decreased from 9.42 to 6.26.
Subjective sleep improvements were observed in:
- Sleep latency
- Sleep duration
- Daytime dysfunction
"Significant improvements were observed in subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, and daytime dysfunction."
Deep, restorative sleep supports DNA repair, metabolic recalibration, and nervous system balance, providing context for why even modest improvements in sleep efficiency may have broader longevity implications.
Wearables Showed Greater Nighttime Relaxation
Wearable data showed measurable changes in nervous system balance. Several metrics improved including:
Heart rate during sleep decreased significantly in the first week and stayed low throughout the study.
"Sleep heart rate significantly decreased in the first week after supplement intake and remained stable at lower values."
Sleep recovery score increased by 0.76 points
"The sleep recovery score showed a significant improvement of 0.76 points after 4 weeks."
Electrodermal activity, a measure linked to stress-related nervous system activation, decreased significantly in the first week.
"Electrodermal activity, a stress-related measure, significantly decreased."
These changes suggest reduced sympathetic ("fight-or-flight") activity and greater nighttime relaxation.
Sleep duration and sleep stage distribution did not significantly change, indicating improvements were more related to nervous system recovery than to increased total sleep time.
Conclusion
Four weeks of combined GABA and L-theanine supplementation improved sleep quality in adults with sleep complaints, alongside measurable reductions in heart rate and electrodermal activity during sleep.
"The improvement in PSQI scores we observed was greater than that in previous reports, suggesting a synergistic or additive effect of the GABA and L-theanine combination."
The greater magnitude of improvement observed here suggests a possible synergistic benefit.
While preliminary, these findings suggest that the combination may support sleep quality without pharmacologic intervention.
