Does L-Theanine Help Sleep? A Comprehensive Analysis

Does L-Theanine Help Sleep? A Comprehensive Analysis

Sleep disturbances have become increasingly prevalent, affecting millions worldwide. From stress-induced insomnia to irregular sleep patterns caused by technological distractions, many individuals find themselves seeking solutions to improve their sleep quality.

Amidst this quest for better sleep, L-Theanine has emerged as a popular supplement purported to aid in relaxation and promote sleep. But does it truly live up to its claims?

In this article, we will explore the scientific evidence surrounding L-Theanine and its potential role in improving sleep.

What is L-Theanine?

L-Theanine is a non-protein amino acid primarily found in tea leaves, particularly in green tea (Camellia sinensis). It is known for its ability to induce relaxation without sedation, leading to increased attention and focus. It is believed to modulate neurotransmitters in the brain, including gamma-aminobutyric acid (GABA), serotonin, and dopamine, which play crucial roles in regulating mood and sleep-wake cycles.

The Science Behind L-Theanine and Sleep

Numerous studies have investigated the effects of L-Theanine on sleep quality and duration. One notable aspect of L-Theanine is its ability to promote relaxation without causing drowsiness, making it an appealing option for those seeking better sleep without the risk of morning grogginess.

But how does L-Theanine have this effect on sleep?

Regulation of Neurotransmitters

Research suggests that L-Theanine may enhance sleep quality by reducing anxiety and promoting relaxation. It works by boosting the levels of calming brain chemicals like GABA, serotonin, and dopamine in the brain. These neurotransmitters play a crucial role in regulating our emotions, mood, alertness, and sleep.

Interestingly, L-Theanine can also act as a competitive glutamate antagonist due to its similar chemical structure to glutamate. This means that L-Theanine can compete with glutamate, an excitatory neurotransmitter, for receptor sites in the brain, thereby reducing neuronal excitability and promoting relaxation and sleep.

Influence on Alpha Brain Waves

Alpha brain waves are associated with a state of wakeful relaxation and are typically present when individuals are in a relaxed but alert state. Studies have shown that L-Theanine supplementation can increase alpha brain wave activity, indicating a heightened state of relaxation without sedation. This relaxation response may facilitate the transition to sleep and promote deeper, more restorative sleep stages.

For example, Rao et al. (2015) discovered that the administration of 200 mg of L-Theanine before bed improved sleep quality not by sedation but through anxiolysis via the induction of alpha waves. The researchers suggest that L-Theanine can be used as a safe natural sleep aid.

L-Theanine and Sleep Studies

Researchers have delved into understanding how L-Theanine may influence various aspects of sleep, from relaxation to sleep onset and maintenance. Here are some key studies shedding light on the relationship between L-Theanine supplementation and sleep enhancement.

L-Theanine and Sleep Quality

L-Theanine has been the subject of numerous scientific studies in relation to sleep quality. In a randomized controlled trial, Lyon et al. (2011) observed that young males diagnosed with attention-deficit hyperactivity disorder who consumed two chewable L-Theanine daily (400 mg total) for six weeks had higher sleep percentages and sleep efficiency scores compared to the placebo group. This is significant as sleep problems are common in children with ADHD, and improving sleep quality can have a positive impact on their overall health and behavior.

Research also indicates a synergistic relationship between L-Theanine and caffeine. L-Theanine is often consumed in conjunction with caffeine, as it is naturally present in tea alongside this stimulant. While caffeine can have stimulating effects that interfere with sleep, the addition of L-Theanine may attenuate these effects by promoting relaxation and counteracting caffeine-induced jitters. This relationship highlights its potential utility in supporting alertness during the day while preserving sleep quality at night.

For example, Baba et al. (2023) observed that L-Theanine suppresses the increase in caffeine-induced wakefulness after sleep onset and helps maintain sleep quality in healthy young women. The accumulating evidence from various studies underscores the potential of L-Theanine to positively influence sleep quality, offering hope for individuals seeking natural solutions to sleep disturbances.

L-Theanine and Sleep Duration

Research suggests that L-Theanine can significantly increase sleep duration, especially when combined with GABA, another neurotransmitter. Kim et al. (2019) found that mice given a GABA/L-Theanine mixture (100/20 mg/kg) showed a decrease in sleep latency and an increase in sleep duration compared to GABA or theanine alone. The mixture also led to a significant increase in rapid eye movement (REM) and NREM compared to controls. This study implies that GABA and l-theanine have a positive synergistic effect on sleep quality and duration as compared to GABA or l-theanine alone.

A later study by Dasdelen et al. (2022) also confirmed the relationship between L-Theanine and sleep quality. The researchers observed that L-Theanine increases dopamine, serotonin, and melatonin, and improves sleep latency and duration even after caffeine administration.

L-Theanine and Sleep Latency

Sleep latency refers to the amount of time it takes for a person to transition from full wakefulness to sleep. For those struggling with insomnia or other sleep disorders, reducing sleep latency can be a significant benefit.

Research has shown that L-Theanine may have a positive impact on sleep latency. For example, Hidese et al. (2019) found that scores for sleep latency, sleep disturbance, and use of sleep medication in healthy adults reduced after four weeks of 200 mg of daily L-Theanine compared to a placebo group.

2022 randomized controlled trial investigated the effects of a supplement containing 150 mg alpha-s1-casein tryptic hydrolysate and 50 mg L-Theanine versus placebo on poor sleep patterns among 39 working adults. After four weeks of daily supplementation, the authors found that those who took the L-Theanine-containing supplement experienced improved sleep latency and duration, increasing their total average sleeping time by 45 minutes compared to the placebo group.

These findings suggest that L-Theanine supplementation holds promise as a natural aid in improving sleep quality and addressing sleep-related issues.

Recommended Dosage of L-Theanine for Sleep

The recommended dosage of L-Theanine for sleep varies depending on a number of factors, including age, overall health, and the severity of the sleep issues. However, a general guideline that's often suggested is to take between 100 to 200 mg of L-Theanine about an hour before you plan to go to bed. This gives the supplement enough time to start working its magic and help you relax.

For those aiming for a holistic approach to cognitive wellness and better sleep, NMN Bio's NAD+ Brain offers a promising solution. With 100 mg of L-Theanine and 50 mg of apigenin per serving, a potent natural compound known for its calming influence on brain cells, it could be just what you're looking for. Depending on your needs, you can take from one to seven capsules per day, ideally before 2 PM, due to the presence of caffeine in this supplement blend. NAD+ Brain is a nootropic supplement that offers the right ratio of L-Theanine and caffeine for focus and concentration during the day (without the jitters of coffee), and nourishes your brain to function and perform the best it can. This proprietary blend with 12 ingredients, aims at slowing down the aging process in the brain, while keeping neuroinflammation and oxidative stress down. Interestingly, data from wearable devices show increased time of both deep and REM sleep for those who take NAD+ Brain for at least 3-4 weeks. In addition, data show lower resting heart rate, which is a synonym for better physical and cognitive recovery during sleep. 

Remember, L-Theanine and any supplement is just a supplement, not a cure-all. It's meant to complement other healthy sleep habits, like maintaining a regular sleep schedule, creating a restful sleep environment, and avoiding caffeine and other stimulants close to bedtime.

It's also important to note that while L-Theanine is generally considered safe for most people, it can interact with certain medications and may not be suitable for everyone. It is not recommended for pregnant or lactating women.

Other Benefits of L-Theanine

    1. Stress Reduction: L-Theanine, has been shown to promote relaxation without sedation, making it a popular choice for stress reduction. It works by increasing alpha brain waves, which are associated with a state of calmness and relaxation.

    2. Improved Cognitive Function: Research suggests that L-Theanine may enhance cognitive function, including attention, memory, and learning. By increasing levels of neurotransmitters such as dopamine and serotonin, it promotes mental clarity and focus.

    3. Anxiety Relief: L-Theanine has been studied for its anxiolytic effects, helping to alleviate symptoms of anxiety and promote a sense of calmness. It works by modulating neurotransmitter activity in the brain, reducing feelings of stress and promoting relaxation.

    4. Cardiovascular Health: Some studies have indicated that L-Theanine may have beneficial effects on cardiovascular health. It may help lower blood pressure and reduce the risk of heart disease by promoting relaxation of blood vessels and improving circulation.

    5. Immune System Support: L-Theanine has been shown to have immunomodulatory effects, meaning it can help regulate the immune system. By promoting the activity of certain immune cells and reducing inflammation, it may support overall immune function and help the body defend against infections.

    6. Weight Management: While more research is needed, some studies suggest that L-Theanine may play a role in weight management. It may help promote weight loss by increasing metabolism, reducing appetite, and enhancing fat oxidation.

    7. Antioxidant Properties: L-Theanine exhibits antioxidant activity, helping to combat oxidative stress and reduce damage caused by free radicals. By scavenging harmful molecules in the body, it may protect cells from damage and support overall health.

    These diverse benefits make L-Theanine a promising supplement for promoting overall well-being and supporting various aspects of health.

    L-Theanine Side Effects

Common Side Effects

  • Gastrointestinal upset: Tea, especially in high doses, can cause discomfort in the digestive system. This can range from mild nausea to severe stomach pain.
  • Liver problems: Although rare, there have been cases of liver issues reported in individuals consuming green tea extract. It's not clear whether this is due to the L-Theanine content or other components of the extract.
  • Anxiety, irritability, and insomnia: These are potential side effects of the caffeine content in green and black teas. While L-Theanine itself promotes relaxation and sleep, the caffeine in the tea can counteract these effects.
  • Potential risks during pregnancy: There's limited research on the safety of L-Theanine during pregnancy or breastfeeding. However, consuming more than 300 mg of caffeine per day during pregnancy can lead to poor pregnancy outcomes.

Interactions with Other Medications

  • Anti-seizure medications: L-Theanine may interfere with the effectiveness of these drugs, potentially leading to increased seizure activity.
  • Asthma medications: The stimulant effects of L-Theanine might exacerbate symptoms in individuals with asthma.
  • Antidepressants: The calming effects of L-Theanine could potentially enhance the effects of certain antidepressants, leading to increased drowsiness.
  • Blood pressure medicine: L-Theanine may interact with these medications, causing blood pressure to drop too low or rise too high.
  • Anti-clotting medications: L-Theanine could potentially interfere with the blood-thinning effects of these drugs, increasing the risk of clotting.

It's also important to note that L-Theanine may interact with stimulant medications and supplements containing caffeine, potentially causing overstimulation or other adverse effects.

L-Theanine as a Natural Sleep Aid

The evidence surrounding L-Theanine's efficacy in promoting sleep quality is compelling. Studies have consistently demonstrated its ability to help reduce anxiety, enhance relaxation, and improve sleep duration and latency. Moreover, the synergistic relationship between l-theanine and caffeine highlights its versatility in supporting alertness during the day while preserving sleep quality at night.

For individuals seeking a natural approach to managing sleep disturbances, taking L-Theanine supplements may offer a promising solution. However, it's essential to consider individual differences in response and consult with a healthcare professional before initiating supplementation, particularly for those with underlying health conditions or who are taking medications that may interact with l-theanine.

Overall, L-Theanine holds great potential as a safe and effective adjunctive therapy for promoting restful sleep and enhancing overall well-being. As research in this area continues to evolve, l-theanine may emerge as a valuable tool in the management of sleep disorders and the promotion of healthy sleep habits.

Individuals seeking a comprehensive approach to cognitive health and sleep enhancement may find interest in NMN Bio's NAD+ Brain, which incorporates 100 mg of L-Theanine and 50 mg of apigenin per serving, a powerful natural compound that has a calming effect on your brain cells. And remember, your sleep routine starts in the morning. Ideally with at least few minutes of sun exposure, some body movement and proper hydration during morning hours. That's how you set up your body for a good night's sleep, while improving productivity during the day. 

Researched and reviewed by Dr Elena Seranova, Ph.D.

Dr Seranova holds a master's degree in Translational Neuroscience from the University of Sheffield, UK, and a Ph.D in Stem Cell Biology and Autophagy from the University of Birmingham, UK. She is a published author in multiple peer-reviewed journals, including Cell Reports and Developmental Cell.


Baba et al. Theanine maintains sleep quality in healthy young women by suppressing the increase in caffeine-induced wakefulness after sleep onset. Food & Function. (2023)

Dasdelen et al. A Novel Theanine Complex, Mg-l-Theanine Improves Sleep Quality via Regulating Brain Electrochemical Activity. Frontiers in Nutrition. (2022)

Hidese et al. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients. (2019)

Kim et al. GABA and l-theanine mixture decreases sleep latency and improves NREM sleep. Pharmaceutical Biology. (2019)

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