Doctor's Best L-Theanine Contains Suntheanine, Helps Reduce Stress & Sleep, Non-GMO, Gluten Free, Vegan, 150 mg (DRB-00197), 90 Count

I find this particular formulation of L-Theanine to be a very good adjunct to help me fall asleep and stay asleep. This formula by the Doctor's Best brand has "Suntheanine," which is a patented form of the amino acid L-Theanine known to promote relaxation. I've taken this formula steadily for about a year at bedtime with only good results as part of an overall sleep hygiene routine that also includes listening to a Calm sleep story on the app in my phone, next to my bed. Also why I like this particular formulation is that it has just 150 mg of the Suntheanine/L-theanine in it, which is less than most other formulas on the market. IMO, less of something often translates to "more." I don't know how long it stays in the system, but probably not for very long, because I wake up normally, with no leftover drowsiness. Another reason why I like this supplement is because it's NON-hormonal. Some folks use melatonin to promote sleep, but I've always avoided that, since melatonin is a hormone, and from what I understand, it's not meant to be used long-term. For me, this has performed as a safe and effective over-the-counter sleep aid. As of December 2025, it was still reasonably priced.

This supplement really helps with calm focus. I take it in the morning with coffee and it removes any nervous edge from caffeine. Clean product, no aftertaste, works exactly as expected.

This works really great for anxiety, calms me right down when I need it. I don't use it often but it sure is good to have it when I need it. It also helps me after a particularly long hard day at work when I'm having a lot of pain because it just relaxes me. I'm very glad it's not a prescription item. Thank you for having it Amazon!

I was reading online about supplements that boost your serotonin and decided to try this. It elevated my mood but got me antsy. I didn’t take it more than one day. I felt weird & not like myself. I think you should do more research before taking this supplement. That’s my honest opinion. Nothing wrong with the product, just wasn’t for me.

L-Theanine was first recommended to us by a psychiatrist for our younger son when he was in 4th grade and developed a tic due to stress of a teacher in a new school. It didn't do anything for the tic, but our older son took some one day, and really felt great! He's in high school and had been feeling pretty stressed. He said it helped him feel calmer and less anxious while not losing any focus. The good thing is L-Theanine is an amino acid; it's found in green tea. It can cross the blood brain barrier and has a positive effect on alpha-brain waves; it has a relaxing effect, reducing physical and mental stress, boosts mood and cognition. It also acts in concert with caffeine to boost cognitive performance. L-Theanine has been tested on small groups of people with significant sleep disorders, and while it's not overly sedating, it does affect alpha waves and tends to be relaxing. It helps those people with sleep, as it does with anxiety. My husband and I recently added it to our Amazon subscription list of supplements when we read an article in Life Extention Foundation's December 2013 magazine about supplements one should consider adding when facing the flu. It was incredibly timely! No sooner did I get the magazine, read it, stock up and get enough for all the kids, than I got socked with a sinus infection/flu. I have never before gone without a course of antibiotics, but this time really wanted to make the effort. I hunkered down with my supplements - L-Theanine included, ate cooked mushrooms (natural anti-viral) several times, as well as maintaining good hydration, and stayed in bed. I finally made it through my very first painful sinus infection/flu w/o antibiotics! So, yes, I heartily recommend L-Theanine! I'll keep buying it for myself, my husband, and our kids!

L-theanine really is like “safe nicotine without the sketchy baggage.” Both sharpen your mind without putting you to sleep. Both reduce mental noise and help you feel “in the zone.” But unlike nicotine, theanine doesn’t come with dependency, vascular stress, or a dopamine crash. Nicotine lights you up like a firecracker—and then drops you off a cliff. L-theanine is like that cool friend who just brings peace and clarity without causing drama. Take Doctor's Best L-theanine with Doctor's Best magnesium glycinate for best overall results.

Not bad overall but I didn't get the full effect from it

Not effective and cannot return the product either