How L-Theanine Can Help You Stay Calm and Sleep Better

L-theanine lattes are the new mushroom coffee—and, fortunately, a lot better tasting. In LA, you’ll find the amino acid on the menu at influencer hot spot Alfred Coffee in its Bolt Energy drink, paired with biotin and B vitamins. Beyond Juicery+Eatery (which has locations in 48 states) has it in their Iced Functional Lattes.

And it’s not just popping up in lattes. L-theanine is a core ingredient in NA drinks like Trip (which has taken over Whole Foods everywhere), Recess’s adaptogenic Mood beverages, and Hiyo social tonics.

Why the sudden obsession and, more importantly, is it worth the hype? We talked to functional-medicine doctors to find out.

What is l-theanine?

L-theanine is a non-protein amino acid that can be found naturally in green, black, and oolong teas, says Yoshua Quinones, MD, an internal medicine doctor with Medical Offices of Manhattan and a contributor to LabFinder. It works as an antioxidant in the body, helping to reduce inflammation. “It’s well-known for its effect of feeling calm yet alert,” Dr. Quinones says.

If you’re a matcha drinker, you’ve experienced this firsthand. The caffeine in the green tea leads to a feeling of alertness, but it’s the l-theanine that prevents the jittery effect that espresso or coffee can have. Sunjya Schweig, MD, a functional medicine doctor at the California Center for Functional Medicine, says that’s exactly why it’s being added to coffee drinks; you can stick with coffee instead of ordering matcha but experience a similar feeling.

“It’s become increasingly popular as a way for people to feel calmer and more focused without feeling sedated,” says Jennifer Timmons, MD, a functional medicine doctor and the medical director of Timmons Wellness. L-theanine does this by influencing several neurotransmitter systems in the brain, including the GABA, dopamine, and serotonin systems. “It also increases what’s called alpha brainwave activity, which is associated with a mental state of alert relaxation,” says Dr. Timmons. “So instead of feeling drowsy and relaxed, you’re actually alert and relaxed. It also directly affects cortisol and lowers cortisol levels, which can help you feel more relaxed as well.”

The calming effect is why l-theanine has become a go-to ingredient in nonalcoholic drinks, too, according to the doctors we talked to. If you have trouble sleeping due to anxiety or racing thoughts, popping a l-theanine supplement could help due to its cortisol-lowering effects.

Jeffrey Bland, PhD, a biochemist and longevity expert at Big Bold Health, says that some clinical studies have shown that l-theanine can lead to falling asleep faster when it’s taken 30 to 60 minutes before bed, even though it’s not considered a sedative. Additionally, a 2022 study published in Frontiers in Nutrition found that supplementing with l-theanine can lead to better sleep quality. Researchers explain that it does this by dampening overstimulation in the brain, which can otherwise interfere with sleep.

Why is l-theanine popular right now? After all, anxiety and sleep problems are nothing new. Functional medicine doctor and Anderson Longevity Clinic founder Brian Anderson, DO, says it stems from the rising interest in brain health. “Optimized brain health is one of the hottest trends in longevity-based health care right now. L-theanine taps into this trend and is readily available,” he says.

Dr. Schweig adds that the search for a better night’s sleep plays a big part in the supplement’s popularity as well. “People are just really stressed and can’t sleep well, and if they ask ChatGPT or other AI tools what can help, it’s a likely solution that they’ll come across,” he says.