Melatonin and L-theanine are two popular dietary supplements taken to relieve sleeplessness and to promote relaxation.
They both have a calming effect on the mind, but work by different mechanisms of action. Melatonin is the body’s main sleep regulating hormone, produced endogenously from the neurotransmitter serotonin.
Melatonin supplements are primarily used to alleviate interrupted sleep patterns, jet lag and insomnia. However, there is growing research suggesting that it has mood-related benefits as well.
L-Theanine is an amino acid commonly used to alleviate stress and anxiety. It is frequently taken in combination with caffeine in a nootropic stack to support cognitive abilities, focus and attentional control.
L-Theanine works by increasing levels of the neurotransmitters serotonin, dopamine, and gamma-aminobutyric acid (GABA). It has been shown to influence brain EEG patterns to produce more alpha waves, which are indicative of lower stress levels and improved attention and alertness.
There are some instances in which combining these products may have additive benefits. Depending on your supplementation goals, Melatonin or L-Theanine can be taken separately or as a combined supplement in capsule or tablet forms.



- Reduces insomnia, jet lag & daytime fatigue
- Promotes restful sleep & calm mood
- Supports brain function, wellbeing & anti-aging
Melatonin Supplement Review
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Produced by a small, pine-cone shaped organ located in the middle of the brain known as the pineal gland, melatonin is an indole hormone regulating wakefulness and sleep in humans and other animals.
Specifically, melatonin helps keep circadian rhythms synchronized to ensure sleep-waking timing in humans remains in harmony with daylight and nighttime.
Secretions of this neurohormone are low during the daytime and increase at night based on detection of light in the ambient environment. Increasing levels of this hormone through supplementation has been shown to improve sleep latency, quality and duration in multiple research studies.
In addition to exerting sleep-awake effects by activating melatonin receptors in the brain, melatonin may improve overall health by serving as an antioxidant and protecting nuclear and mitochondrial DNA. [1, 2]
Oral melatonin is used to relieve symptoms of insomnia, jet lag, shift-work disorder and other sleep-wake problems preventing people from sleeping normally.
This hormone also affects a number of other bodily functions and is being researched for high blood pressure, anxiety, anti-cancer effects, mood disorder, cognitive function, digestive health and more.
Blind people suffering circadian rhythm disorders due to their inability to perceive the difference between night and day take melatonin to help restore normal levels of melatonin in the brain.
Supplements containing this ingredient may also be useful in re-establishing natural circadian rhythms in people diagnosed with:
- Dementia/Alzheimer’s
- Chronic fatigue syndrome
- Insomnia caused by taking beta-blockers
- Seasonal affective disorder
- Depression
- Fibromyalgia
- Sleep problems attributed to menopause
- Attention deficit hyperactivity disorder
Melatonin as a topical agent is used to protect skin against sunburn and damage caused by ultraviolet light. [3]



- Supports focus, attention & mood
- Helps to reduce stress & anxiety
- Neuroprotective & increases NGF
L-Theanine Supplement Review
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Extracted from green tea leaves belonging to the Theaceae family of trees and shrubs, L-theanine is a non-proteinogenic amino acid. This means that although it has the chemical structure of an amino acid (a building block of proteins), it is not used in the body to make proteins.
Research shows that supplementing with L-Theanine (Gamma-ethylamino-L-glutamic acid) promotes subjective feelings of tranquility and reduces mental and physical stress.
As a dietary supplement, it has been used for anxiety, to promote feelings of relaxation, support cognitive function and for mood enhancement.
L-Theanine has been described as exerting calming effects without acting as a sedative. Users report taking it to provide relief from anxious thoughts and inability to quiet the mind before sleep.
One study evaluated the effectiveness of L-theanine on people with schizoaffective disorder and schizophrenia. Results of the study found that augmenting antipsychotic therapy with L-theanine significantly reduces anxiety and agitation commonly affecting patients diagnosed with schizophrenic disorders. [6]
Clinically, L-Theanine has also been studied for hypertension and some symptoms of Alzheimer’s disease. It may also enhance the effects of chemotherapy medications. [4] However, it has not been approved by the FDA as a drug for the treatment of any medical conditions.
Combining caffeine and theanine boosts mood, expedites reaction times and has beneficial effects on numeric working memory. Consequently, L-theanine is a popular nootropic supplement for students studying for exams and older adults experiencing thinking and memory problems. [5]
L-theanine also exhibits neuroprotective properties and has been shown in animal research to prevent certain forms of neuronal damage. It has also been shown to increase the synthesis of nerve growth factor, which is involved in neuroplasticity.
L-Theanine and Melatonin for Sleep
Taking L-theanine and melatonin together may help support sleep quality and ability to fall asleep at night. They may work in conjunction to relax the mind and body and regulate sleep cycles simultaneously.
While L-theanine reduces feelings of physical and mental stress, melatonin works to help induce sleep by increasing levels of this natural sleep-regulating hormone in the brain.
There are no research studies available to evaluate clinical efficacy. However, based on anecdotal user reviews, there are reports of this combination being more effective than using either supplement individually.
Melatonin is well-established as being effective for addressing sleep problems. The Natural Medicines Comprehensive Database reports that it can improve the time it takes to fall asleep and improve symptoms of insomnia in certain circumstances.
They report “Taking melatonin 3 mg daily for 4 weeks seems to increase the percentage of rapid-eye movement (REM) sleep in adults with reduced REM sleep. Also, taking melatonin 6 mg daily for 10 days seems to reduce the time it takes to fall asleep and the number of transitions from sleep to being awake in elderly individuals with sleep-wake cycle disturbance and dementia.”
It also appears to promote a modest improvement in subjective feelings of sleep quality. However, it does not appear to significantly improve sleep efficiency, which is a measure of the total time spent sleeping at night compared to the total amount of time spent in bed.
Interestingly, in one study on the effects of l-theanine for sleep disorders in children with ADHD, this supplement was shown to improve sleep efficiency.
One randomized, double-blind, placebo-controlled clinical trial on a proprietary brand of L-Theanine called Suntheanine® looked at the effects of this supplement on objective measures of sleep quality.
The study involved 98 male children diagnosed with attention-deficit/hyperactivity disorder (ADHD). Participants consumed 400 mg of l-theanine or a placebo daily at breakfast and after school for six weeks.
Over the treatment period, boys who were taking Suntheanine® experienced significantly higher sleep percentage and sleep efficiency scores compared to those on the placebo. Though sleep latency (time it took to fall asleep) was unchanged, sleep quality was higher with no significant adverse events reported.
There are several dietary supplements available today that contain L-theanine mixed with melatonin. The reviews on these supplements are generally positive and suggest that some people may experience added benefits compared to taking melatonin on its own.
L-Theanine and Melatonin Dosage
What is the recommended dosage for stacking L-theanine with melatonin for sleep? Combination supplements come in capsule form containing 200 mg of L-theanine and three mg of melatonin.
It may not necessary to take these supplements at the same time in order to experience positive effects on sleep cycles. Melatonin is typically taken before bedtime to promote restful sleep.
L-Theanine is typically used during the daytime. In one research study, split dosages of 400 mg per day administered at breakfast and in the afternoon were also shown to improve sleep quality. Therefore, you may not need to take this supplement at bedtime to observed benefits.
Crossing the blood-brain barrier in about 30 minutes, L-theanine remains in the bloodstream for around five hours following administration. Studies report that giving subjects dosages of L-theanine between 200 and 250 mg provide adequate anxiolytic effects. [8]
However, individual differences regarding metabolism, current health and body chemistry may require some users take more or less of L-theanine to achieve desired effects. Dosages as high as 1200 mg of L-theanine have been taken without harmful side effects. [9]
A typical adult dosage of melatonin for sleep is between two-tenths and five milligrams one hour before going to bed. Doctors recommend starting with a small dose and slowly increasing the dose if needed.
Children can take melatonin for sleep but in smaller doses. Taking too much melatonin at one time can cause nausea, headache, mild anxiety, dizziness and also interfere with sleep. [11]
Nature Made Melatonin Plus L-Theanine 200mg
Nature Made Melatonin Plus L-Theanine 200mg is a popular brand of combination sleep supplement containing both of these ingredients.
Containing no preservatives or artificial flavors, Nature Made Melatonin Plus L-Theanine 200 mg comes in easy-to-swallow soft gels.
Users should take one soft gel about one hour before bedtime. The only difference between Nature Made Melatonin plus L-theanine and Nature Made Sleep is the cost of these supplements.
User reviews of this product are highly positive with 70% of reviewers providing a 5-star review. User testimonials say that it helps to alleviate excessive mental chatter at night, making it easier to relax, fall asleep and stay asleep throughout the night.
Before taking L-theanine and melatonin together, ask your doctor if any of the medications you are taking will interact negatively with this supplement.
L-Theanine and Melatonin Side Effects
Both L-theanine and melatonin are well-tolerated as dietary supplements. When combined, they may promote a synergistic effect causing greater sleepiness than if taken separately.
In addition to daytime drowsiness and dizziness, melatonin may cause:
- Headaches
- Nausea
- Hypotension
- Temporary disorientation/confusion
- Mild shakiness
- Short-lasting moodiness (depression, anxiety)
Certain medications may interact adversely with melatonin. These include anti-platelets, anticoagulants, anticonvulsant and diabetic medications.
Headaches, stomach discomfort and dizziness are the most commonly reported side effects of L-theanine. Other less common side effects include:
- Lowering blood pressure: People taking drugs for hypotension should be aware of this potential side effect and discuss it with their doctor
- Reduced energy: With its ability to induce relaxation, L-theanine may also reduce overall physical and mental energy as well
- Altering serotonin levels: Both an increase and decrease in serotonin has been reported in people taking L-theanine. Serotonin is a neurotransmitter involved in mood, appetite, sleep and libido
- Vomiting: A rare side effect of L-theanine use, vomiting after taking a normal dose may mean the supplement brand is of low quality or it may have interacted adversely in your stomach with a certain substance
- Weight loss: A few studies with rodents found that L-theanine may have an antiobesogenic effect that could cause a small but measurable weight loss in certain individuals [13]
Common side effects reported by users of L-theanine/melatonin supplements include dizziness, mild headache/head pain and feeling slightly hungover. Less common side effects involve low blood pressure, irritability, stomach pain and anxiety. [7]
While subacute and acute toxicity tests have not shown L-theanine is actually toxic in high amounts, studies are needed to determine if long-term, high-dosage use of L-theanine may cause organ disease, organ failure or other harmful side effects. [10]
This amino acid may also interfere with the ability of immunosuppressant drugs to suppress the immune system and reduce symptoms of autoimmune diseases. Always check with your doctor before taking L-theanine and melatonin together if you take any kind of over-the-counter or prescription medication daily. [12]
L-Theanine, Caffeine and Melatonin
As a dietary supplement, L-Theanine is commonly stacked with caffeine. Many users are interested in understanding the effects of combining melatonin with L-Theanine and Caffeine supplements.
L-Theanine is derived naturally from green tea leaves, where it exists in combination with caffeine. Use of these supplements together has been shown to enhance cognitive skills such as reaction time and memory.
This nootropic stack may support mental accuracy and boost the ability to evaluate and process visual information. Studies also show that people susceptible to anxiety benefit from the calming effects of L-theanine and caffeine without experiencing sedation or impaired mental faculties. [14]
Although it would seem counterintuitive, taking melatonin and caffeine together can sometimes help users experience a deeper, almost hypnotic-like sleep that relieves fatigue for a short period of time. This is because caffeine increases the bioavailability of melatonin.
However, mixing caffeine with melatonin and l-theanine does not appear to cause the same effects in all users. Response to this stack largely depends on sensitivity to caffeine.
If you are regularly able to consume caffeinated products late in the evening without experiencing insomnia, this stack could work for you. If drinking caffeine makes it difficult for you to fall asleep, do not consume it before bedtime.
Caffeine may also cause unwanted side effects like:
- Dizziness
- Burning, prickling sensations on the skin
- Palpitations
- Restlessness
- Weakness [15]
Foods containing small amounts of caffeine like chocolate or soda will not interfere with melatonin inducing sleepiness, unless large amounts are consumed.
In general, if you are interested in using L-Theanine supplements to promote sleep, you should look for versions of this supplement are caffeine-free. You can either buy a pre-made product like Nature Made Sleep or purchase bulk L-theanine and melatonin supplements individually to combine on your own.
- Hardeland, R. Antioxidative protection by melatonin: multiplicity of mechanisms from radical detoxification to radical avoidance.2005 Jul;27(2):119-30.
- Recep SutcuZafer,Yonden Aysegul,YilmazNamik Delibas. Melatonin increases NMDA receptor subunits 2A and 2B concentrations in rat hippocampus. Molecular and Cellular Biochemistry, February 2006, Volume 283, Issue 1-2, pp 101-105.
- Tobias W. Fischer et al, Melatonin as a major skin protectant: from free radical scavenging to DNA damage repair. Experimental Dermatology, 6 August 2008.
- https://www.webmd.com/vitamins/ai/ingredientmono-1053/theanine
- Sang-Ki Park. A Combination of Green Tea Extract and l-Theanine Improves Memory and Attention in Subjects with Mild Cognitive Impairment: A Double-Blind Placebo-Controlled Study. J Med Food, 14 (4) 2011, 334-343.
- Miodownik C. L-theanine relieves positive, activation, and anxiety symptoms in patients with schizophrenia and schizoaffective disorder: an 8-week, randomized, double-blind, placebo-controlled, 2-center study. Clin Psychiatry. 2011 Jan;72(1):34-42.
- https://www.webmd.com/drugs/2/drug-150123/melatonin-theanine-oral/details/list-sideeffects
- Kimura K1, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007 Jan;74(1):39-45.
- https://mentalhealthdaily.com/2015/07/29/l-theanine-side-effects-adverse-reactions-list
- https://www.drugs.com/npp/l-theanine.html
- https://sleep.org/articles/how-much-melatonin-to-take/
- https://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/melatonin-side-effects/faq-20057874
- https://mentalhealthdaily.com/2015/07/29/l-theanine-side-effects-adverse-reactions-list/
- https://www.psychologytoday.com/us/blog/sleep-newzzz/201708/what-you-need-know-about-l-theanine
- https://www.ehealthme.com/drug-interaction/melatonin/caffeine/
Article last updated on: July 6th, 2018 by Nootriment