L-Theanine is a unique amino acid in that it’s not commonly found in our diet but is actually considered a non-dietary amino acid similar to the more popular l-citrulline.
Theanine is most commonly supplemented by users looking for increased levels of relaxation and the reduction of stress. It also shows some promise in enhancing attention and cognition making it a theoretical nootropic as well.
Theanine’s most prominent benefit is the ability to increase relaxation. It is extremely well studied in this regard and appears to be most powerful in those who suffer from high anxiety as compared to someone who is experiencing acute onsets of stress. One particular study utilized the stress which occurs from mental arithmetic tasks and found that 200mg of theanine was effective at reducing anxiety and stress, along with reducing average heart rate.
Although theanine does not provide a sedative effect, it may improve sleep quality when taken for long periods of time (4+ weeks). It showed this in a study in young boys (7-12 years old) who took 200mg twice daily for 6 weeks. The study found theanine to be efficient at reducing sleep disturbances, and less movement during sleep was noted.
Theanine binds to glutamate receptors inhibiting the excitatory neurotransmitter glutamate from being able to increase brain function. By eliminating this excitatory neurotransmitter, it allows people to calm down and feel relaxed more easily.
Theanine has also been shown to increase blood levels of serotonin as well as GABA, both of which have been linked to increased levels of relaxation and potential sedation.
Standard dosing of theanine is 200mg in a single serving, approximately 30 minutes prior to the desired relaxation time. For enhanced sleep, 200mg in two separate doses per day is the most proven dosage, yet due to the age of those studied (7-12 year old boys) a higher dose of 400mg two times per day may be more applicable for adults.