L-theanine is a unique, non-proteinogenic amino acid found almost exclusively in the tea plant (Camellia sinensis) and has a long history of safe use in Japan. Thorne's Theanine features Suntheanine®, a patented form of L-theanine backed by more than 50 clinical studies over the past two decades—including Japanese research showing that 200 mg of L-theanine increases alpha-wave activity and relaxation, promoting a calm yet focused state within about 40 minutes of intake.

This fast-acting formula—with many people noticing effects within 20 minutes—works by increasing alpha-wave activity for relaxation, enhancing dopamine and serotonin to support mood, focus, and memory, and boosting GABA production to help calm the body's stress response. It also helps balance cortisol and neurotransmitter activity to reduce the mental and physical toll of stress, decreases the time it takes to fall asleep, improves overall sleep quality, and lessens next-day dysfunction following a poor night's sleep.

Thorne's Theanine is well-suited for anyone looking to support cognitive function, maintain mental clarity during stressful periods, promote brain cell membrane fluidity and cognitive health with age, modulate cortisol for a healthier stress response, or simply achieve more restful sleep.