Why Combine Caffeine with L-Theanine?
L-Theanine is an amino acid found in green tea that promotes alpha brain wave activity — the pattern associated with calm, focused attention. When paired with caffeine, it preserves the alertness and cognitive enhancement benefits while eliminating jitteriness, anxiety, and the post-caffeine crash. This isn't pseudoscience: multiple peer-reviewed RCTs confirm the synergistic effect.
How Caffeine:L-Theanine Ratios Work
The standard recommendation is 1:2 caffeine:theanine (e.g., 100mg caffeine + 200mg L-Theanine). But this ratio is just a starting point. Users who are caffeine-sensitive or anxiety-prone often benefit from 1:3 or even 1:4 ratios. Users with low sensitivity who need maximum focus can use 1:1 or 1:1.5. The calculator above personalizes this based on your inputs.
Caffeine Cutoff Time Calculator
Caffeine has a half-life of 3–7 hours depending on your metabolism. "Fast metabolizers" (CYP1A2 gene variant) clear caffeine in ~3.5 hours; "slow metabolizers" take ~7 hours. Your cutoff time = bedtime minus 2 half-lives. This ensures less than 25% of caffeine remains at sleep onset. The calculator above computes this automatically based on your bedtime and metabolism speed.
How Much L-Theanine is Safe?
L-Theanine has an excellent safety profile. Studies have used up to 1,200mg/day without adverse effects. It does not cause drowsiness at typical doses (100–400mg) — it promotes calm alertness, not sedation. Very high doses (>800mg) may cause mild tiredness in some individuals. There are no known drug interactions or contraindications.