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L-Theanine for Sleep

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March 13, 2025

L-Theanine for Sleep: How This Amino Acid Helps You Relax

Medically reviewed by: 

Dr. Shiyan Ooi

School of Medical Sciences, University of Manchester

L-Theanine is an amino acid commonly found in tea leaves, particularly green and black tea. It is known for its calming effects and potential benefits for sleep quality.

How L-Theanine Promotes Relaxation

L-Theanine is believed to enhance sleep by:

  • Boosting alpha brain waves, which promote relaxation
  • Reducing stress and anxiety by regulating cortisol levels
  • Enhancing the production of GABA, serotonin, and dopamine

Studies suggest that L-Theanine can improve sleep efficiency and reduce the time it takes to fall asleep (National Institutes of Health).

How to Use L-Theanine for Sleep

L-Theanine is available in various forms, including:

  • Tea: Drinking green or black tea can provide a natural source of L-Theanine.
  • Supplements: Capsules or tablets (100-400 mg) can be taken 30-60 minutes before bed.

Potential Side Effects

While generally safe, some individuals may experience:

  • Dizziness
  • Gastrointestinal discomfort
  • Lower blood pressure

It's best to start with a lower dose and consult a healthcare provider if taking medications.

Conclusion

L-Theanine is a natural way to support relaxation and better sleep. By incorporating it into your nightly routine, you may experience improved sleep quality without the side effects of traditional sleep aids.

Dr. Shiyan Ooi

Dr. Shiyan Ooi is a medical doctor with over a decade of experience treating patients with chronic conditions. She graduated from the University of Manchester with a Bachelor of Medicine and Surgery (MBChB UK) and spent several years working at the National Health Service (NHS) in the United Kingdom, several Singapore government hospitals, and private functional medicine hospitals. Dr. Ooi specializes in root cause analysis, addressing hormonal, gut health, and lifestyle factors to treat chronic conditions. Drawing from her own experiences, she is dedicated to empowering others to optimize their health. She loves traveling, exploring nature, and spending quality time with family and friends.