Melatonin, Magnesium, and L-Theanine: What Each Sleep Supplement Ingredient Actually Does
Reviewed by Dr. Kathleen Valenton, Board Certified OB/GYN
Published: March 2026 | 4 min read
Sleep Supplements Are Everywhere. But Do You Know What You Are Actually Taking?
The sleep supplement market has exploded in recent years, and many products combine multiple ingredients into a single formula. But most consumers do not know what each ingredient actually does, how it works in the brain, or whether the dose they are taking is supported by research. Understanding the distinct role of each ingredient can help you make more informed choices.
Melatonin: The Sleep Timing Signal
Melatonin is a hormone your brain naturally produces to regulate your sleep-wake cycle. It is secreted by the pineal gland in response to darkness, signaling to your body that it is time to prepare for sleep. Supplemental melatonin works by reinforcing this natural signal, which is why it is most effective for supporting sleep onset (the time it takes to fall asleep).1
A meta-analysis of 19 randomized controlled trials involving 1,683 subjects found that melatonin significantly reduced sleep onset latency, increased total sleep time, and improved overall sleep quality compared to placebo.1* The researchers also noted limited evidence of habituation or tolerance, and a favorable safety profile for short-term use.
What melatonin does: Helps signal the brain that it is time to sleep. Most useful for supporting the transition from wakefulness to sleep.*
What melatonin does not do: It is not a sedative. It does not force you to sleep or address the underlying causes of wakefulness, such as stress or an overactive mind.
L-Theanine: The Calm-Down Signal
L-Theanine is an amino acid found naturally in tea leaves that promotes relaxation without causing drowsiness. It works primarily by supporting alpha brain wave activity, a type of electrical activity in the brain associated with a state of calm, wakeful relaxation, similar to what is observed during meditation.2
What L-Theanine does: Helps quiet mental activity and support stress-related arousal, making it easier to transition into sleep.*
What L-Theanine does not do: It does not induce drowsiness or act as a sedative. It creates the conditions for sleep by calming the mind, rather than directly initiating sleep.
Magnesium: The Nervous System Relaxant
Magnesium is an essential mineral involved in hundreds of biochemical processes in the body, including nervous system regulation. Its relevance to sleep centers on its role in supporting the activity of GABA (gamma-aminobutyric acid), the brain’s primary inhibitory neurotransmitter. GABA helps quiet neural activity and promote relaxation.4
Magnesium deficiency has been associated with sleep disturbances, and some clinical research suggests that supplementation may support sleep quality, particularly in individuals who are not getting adequate magnesium from their diet.4* Different forms of magnesium have different absorption profiles. Magnesium citrate is one of the more bioavailable forms commonly used in supplements.
What magnesium does: Supports nervous system relaxation and GABA activity, which may help the body prepare for sleep.*
What magnesium does not do: At typical supplement doses, it is not a standalone sleep aid. Its role is supportive, particularly for individuals with suboptimal magnesium intake.
How These Ingredients Work Together
These three ingredients address different aspects of the process that leads to sleep. Melatonin signals the brain that it is time to sleep. L-Theanine helps support calm. Magnesium supports the nervous system to allow the body to settle into rest.* When combined in a single formulation, they can complement each other by targeting different barriers to falling asleep.
“One of the things I appreciate about a multi-ingredient sleep formulation is that it addresses the problem from multiple angles. Melatonin alone may not be enough if your mind is racing from stress, and a calming ingredient alone may not be enough if your circadian rhythm is off. The combination approach makes sense from a physiological standpoint.”
— Dr. Kathleen Valenton, Double-Board Certified OB/GYN, Chief Medical Officer at Lemme
How Lemme Sleep Gummies Support Restful Sleep
Lemme Sleep Gummies are formulated with a combination of ingredients that address multiple aspects of the sleep process.
Each serving (2 gummies) contains Melatonin (5 mg), L-Theanine (50 mg), Magnesium as Magnesium Citrate (20 mg), and an Herbal Complex that includes Chamomile Extract (Matricaria Chamomilla, flower), Elderberry Extract (Sambucus Nigra, Fruit), and Lavender Extract (Lavandula). Suggested use is 2 gummies 30 minutes before bed.*
Lemme Sleep Gummies are vegetarian, gluten-free, and formulated without synthetic colors.*
FAQ
Do I need all three ingredients, or is one enough?
It depends on what is keeping you awake. If your primary issue is sleep timing, melatonin may be sufficient. If stress and mental activity are the problem, L-Theanine may be more relevant. A combination addresses multiple barriers.*
How is L-Theanine different from melatonin?
They work through completely different mechanisms. Melatonin is a hormone that signals sleep timing. L-Theanine is an amino acid that supports relaxation.1,2* Melatonin tells your brain it is time to sleep. L-Theanine helps your brain get quiet enough to listen.
Why magnesium citrate instead of other forms?
Magnesium citrate is one of the more bioavailable forms of magnesium, meaning it may be more easily absorbed by the body. Different forms (oxide, glycinate, citrate, etc.) vary in absorption.4
*These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.
This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any new supplement regimen.
References
1. Ferracioli-Oda E, et al. Meta-analysis: melatonin for primary sleep disorders. PLoS ONE. 2013;8(5):e63773. https://pmc.ncbi.nlm.nih.gov/articles/PMC3656905/
2. Hidese S, et al. AlphaWave® L-Theanine on stress. Neurology and Therapy. 2021;10(2):1061-1078. https://pmc.ncbi.nlm.nih.gov/articles/PMC8475422/
3. Lewis ED, et al. AlphaWave® L-Theanine 28-day trial. Neurology and Therapy. 2024;13(4):1077-1096. https://pmc.ncbi.nlm.nih.gov/articles/PMC11263523/
4. Cho S, Yun S. Herbal and natural supplements for sleep. Psychiatry Investigation. 2024;21(8):810-824. https://www.psychiatryinvestigation.org/journal/view.php?doi=10.30773/pi.2024.0121
ABOUT THE EXPERT REVIEWER
Dr. Valenton is a board-certified OB/GYN at Rodeo Drive Women’s Health Center in Beverly Hills, CA, with over a decade of experience in women’s health. She completed her internship and residency at Cedars-Sinai Medical Center, where she remains an attending physician, after earning her Medical Degree from the University of Vermont College of Medicine and dual Bachelor’s and Master’s degrees in Psychology from UC Berkeley. She is also the Chief Medical Officer at Lemme. Her clinical research interests span mental health, hormonal health, infertility, PCOS, and menopause.
