L-Ornithine

Tier 3 — weak evidence · Sleep · Ammonia detox · Exercise recovery

An amino acid involved in the urea cycle that helps your body clear ammonia, a metabolic waste product. Small trials show it improves sleep quality when taken before bed and reduces fatigue during prolonged exercise. Often combined with L-arginine for growth hormone release, though the GH effect is modest and short-lived. Very safe with no serious side effects reported in clinical studies.

Dose: 400–800 mg before bed for sleep or 2–6 g before exercise for recovery