L-Theanine
L-theanine is a non-protein amino acid found primarily in tea leaves (Camellia sinensis), particularly green tea. It is valued for its ability to promote a state of calm alertness without causing sedation, making it one of the few compounds that can reduce stress while maintaining mental clarity. It readily crosses the blood-brain barrier, typically producing noticeable effects within 30-60 minutes of ingestion.
Research Evidence
Reduces subjective stress and anxiety
StrongPromotes relaxation and increases alpha brain wave activity
StrongCounteracts jitteriness and anxiety from caffeine
ModerateImproves sleep quality without daytime drowsiness
ModerateMay support attention and cognitive performance under stress
ModerateMay help maintain healthy blood pressure under stress
LimitedExpert Evidence
36 references from 4 experts
Safety & Cautions
Side Effects
- Unusually vivid dreams
- Possible worsening of sleepwalking or night terrors
- Mild headache at high doses
- Slight drop in blood pressure
L-theanine is generally very well-tolerated with a strong safety profile across clinical studies. Those prone to sleepwalking or night terrors should use caution, as it can intensify dream vividness and potentially exacerbate these conditions.
Pairs Well With
Price Comparison
From $0.08/ct
N
NutricostBest Value
4.6
•240 ct$0.08/ct
$19.95 total
A
Amazing Nutrition
4.5
•120 ct$0.10/ct
$11.99 total
N
NOW Foods
4.7
•120 ct$0.19/ct
$22.86 total
D
Double Wood
4.7
•120 ct$0.11/ct
$13.57 total
I
Integrative Therapeutics
4.6
•60 ct$0.37/ct
$22.00 total
T
Thorne
4.7
•90 ct$0.76/ct
$68.00 total
P
Primal Harvest
4.2
•60 ct$0.62/ct
$36.99 total
O
ONNIT
4.2
•80 ct$1.56/ct
$124.95 total