By Sara Lovelady
Have you ever wondered why drinking a cup of hot tea seems to have a calming effect, even though tea contains caffeine? The answer is L-theanine, an amino acid and a component of black and green tea that helps calm the brain.* If the wheels of your mind can’t stop spinning at night—and that keeps you from falling asleep—L-theanine can be part of the solution.*
More time sleeping, less time tossing and turning
In 2011, a double-blind, placebo-controlled trial studied the effect of L-theanine on boys aged 8 to 12 who were taking stimulating medications. It found that 400 mg of L-theanine daily for six weeks significantly improved their sleep efficiency (the time spent awake versus asleep while in bed).* There was also a small decrease in the boys’ movements while asleep.* However, it did not improve their sleep latency (the time it takes to fall asleep.)
L-theanine promotes a calm mood—which is exactly what you want when you hit the hay.* A 2007 double-blind, placebo-controlled study tested volunteers’ ability to perform math problems in their heads. It found that the people who took L-theanine were less stressed by the task than those who took the placebo pills.* Their heart rates and the level of immunoglobin (a marker of stress) in their saliva were lower than in the folks who took a placebo.*
How does L-theanine work?
L-theanine works by increasing the production of relaxing alpha brain waves, which help ease the transition to sleep.* It also increases levels of GABA, a calming neurotransmitter.* Lastly, L-theanine blocks L-glutamic acid from binding to receptors that cause brain cells to become overexcited.*
The effect of L-theanine on alpha brain waves has been demonstrated in several studies. In one small 1998 trial, female university students took a single dose of 200 mg of L-theanine, and researchers then measured their brain waves. The results showed L-theanine generated alpha waves in the occipital and parietal lobes of the volunteers’ brains.* One interesting thing about this study is that L-theanine worked best for the people who needed it the most—the effect was more pronounced in the students who were experiencing more stress at the time of the test.* A 2003 study found this same effect: an increase in alpha brain waves in stressed but not in non-stressed young men.*
A 2008 study found a relatively low single dose of L-theanine (50 mg) also increased alpha waves. Researchers gave 35 healthy young people L-theanine or a placebo. They then measured their brain waves while the participants relaxed with their eyes closed or engaged in a passive activity. The result was a significant increase in alpha waves in those taking the L-theanine.*
Your cup of tea?
If you want to take advantage of L-theanine’s ability to promote restful sleep, tea before bedtime is probably not the best idea because of the caffeine. It makes more sense to take it as a supplement. L-theanine is available in capsules, tablets, gummies and powders. It may also be combined in formulas with other sleep-promoting ingredients such as GABA, nutrients, and sedative herbs that address other aspects of the sleep cycle, such as sleep latency.
* This statement has not been reviewed by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.