What can you tell me about l theanine and about recommended supplement’s

L-theanine may help with sleep, stress, and caffeine-related jitters; the suggested amount depends on how you intend to use it.

• For sleep: 100–200 mg about 30–60 minutes before bed may help with the transition to sleep and sleep depth. 1
• For caffeine-related jitters: 200–400 mg is described as an effective range; 100–200 mg taken with coffee or tea is also mentioned. 2 3
• Other possible effects: It may increase GABA, modestly ease anxiety and stress, slightly improve attention, reduce blood pressure, and support blood-vessel function and blood flow. 4 5
• Upper amount discussed: Up to 900 mg per day was described as potentially safe, but that high a dose may cause substantial sleepiness. 6
• Use caution with vivid dreams or parasomnias: Avoid it if you sleepwalk or experience night terrors; it may intensify dreams. 7

Consider trying one supplement at a time, and discuss supplement use with a healthcare professional. 8