What does L-Theanine do?
L-Theanine acts as a building block to produce relaxing neurotransmitters (brain chemicals) such as GABA. It also changes the effects of glutamate, serotonin and dopamine in different areas of the brain. 1 As a result, L-Theanine reduces feelings of stress, improves concentration and may help to promote more refreshing sleep. Brainwave (electroencephalograph or EEG) studies show that L-Theanine increases alpha wave activity which suggests it relaxes the mind without inducing excessive drowsiness. 2
L-Theanine for relaxation
The relaxing effects of L-Theanine were tested against those of a prescribed benzodiazepine, alprazolam, and placebo, in a study in which volunteers were exposed to a stressful situation in which they expected to receive random electric shocks to one hand. When taking L-Theanine (but not alprazolam) volunteers felt greater tranquillity during the resting phases when they were not anticipating electric shocks and reported feeling calmer. 3
L-Theanine for anxiety
Several studies have shown that the calming effects of L-Theanine are most pronounced in people classified as having high levels of anxiety. 4 L-Theanine also reduces tension and anxiety scores during difficult mental tasks, compared with placebo. 5
L-Theanine for stress
L-Theanine helps to reduce psychological and physical stress responses during demanding tasks. In one study, volunteers were set mental arithmetic tests under time pressure on four separate occasions, during which they took either L-Theanine, placebo or nothing. When taking L-Theanine, their stress responses, such as heart rate were significantly lower than when taking placebo or nothing, and there were indications that this was due to a damping down effect on the sympathetic nervous system and inhibition of brain cell over-excitation. 6 A similar study found that L-Theanine reduced the normal rise in blood pressure that can occur during stressful mental tasks. 7
L-Theanine for sleep quality
L-Theanine was found to improve sleep quality and reduce sleep disturbances in boys with attention deficit hyperactivity disorder (ADHD). The supplement improved sleep efficiency so they spent more time asleep than awake. 8
L-Theanine is well tolerated, with no significant side effects. It may lower blood pressure. Check with your doctor before taking if you are on any medication, including antihypertensive and stimulant drugs.
The correct dosage
The amount of L-Theanine typically found in a cup of black tea is 20mg and in green tea is 25mg to 65mg depending on concentration. 9
A typical dose used in products to aid sleep is 100mg. Higher doses of 200mg to 400mg have been used to treat anxiety and stress.
Nutritional products such as hot chocolate to take before bedtime usually provide around 100mg L-Theanine and this is often combined with B vitamins and another beneficial amino acid, 5-HTP, to promote refreshing sleep.