Which Supplements Can Support Better Sleep?

Getting enough quality sleep is essential for how you feel, think and function during the day. But when falling asleep or staying asleep becomes difficult, it can be tempting to look for a supplement that promises a quick solution.

The reality is more nuanced. Some nutrients and compounds have been studied for their relationship with sleep, but they work in different ways – and the strength of the evidence varies considerably.

From magnesium and melatonin to glycine and L-theanine, understanding what the research actually says can help you make a more informed choice.

In This Guide

• Can supplements actually help you sleep?
• Magnesium and sleep
• Melatonin and sleep
• Glycine and sleep
• L-theanine and sleep
• Vitamin D and sleep
• Which sleep supplement should you choose?
• Supplements vs sleep habits
• Common myths about sleep supplements
• Frequently asked questions

Can Supplements Actually Help You Sleep?

Some supplements may support particular aspects of sleep, but their effects depend on the ingredient, your individual circumstances and what is causing your sleep difficulties.

Sleep is controlled by a complex combination of biological and behavioural factors. Your circadian rhythm, stress, light exposure, physical activity, caffeine intake, diet and daily routine can all affect when you fall asleep and how well you sleep.

This means there is unlikely to be one supplement that solves every type of sleep problem.

Instead, it is more useful to ask a different question: which biological process are you trying to support?

For example, melatonin is closely connected to circadian timing, while magnesium is involved in normal nervous system and psychological function. Other compounds, including glycine and L-theanine, are being investigated for different aspects of sleep and relaxation.

1. Magnesium

Magnesium may support sleep in some people, particularly when dietary magnesium intake is relatively low, although the overall clinical evidence remains mixed.

Magnesium is an essential mineral that contributes to normal functioning of the nervous system, normal psychological function and normal muscle function.

These established physiological roles have made magnesium one of the most widely discussed nutrients in relation to relaxation and sleep.

A systematic review examining magnesium and sleep found associations between magnesium status and sleep quality in observational studies, although results from randomised controlled trials were inconsistent.

More recently, a 2025 randomised, double-blind, placebo-controlled trial investigated magnesium bisglycinate specifically in 155 adults reporting poor sleep.

After four weeks, participants taking magnesium bisglycinate experienced a statistically significant but modest improvement in insomnia severity compared with placebo.

Interestingly, exploratory analysis suggested that participants with lower dietary magnesium intake may have experienced greater improvements.

Want to explore this in more detail? Read our guide: How Can Magnesium Bisglycinate Help You Sleep Better?

2. Melatonin

Melatonin plays a direct role in regulating the body's sleep-wake cycle and has one of the clearest established relationships with sleep.

Melatonin is a hormone naturally produced by the body, primarily in response to darkness. As evening approaches and light exposure decreases, melatonin levels typically rise, helping signal that biological night has begun.

This is why melatonin is fundamentally different from many other ingredients marketed for sleep: it is closely involved in circadian timing.

In the EU, authorised health claims recognise that melatonin contributes to the reduction of time taken to fall asleep when 1 mg is consumed close to bedtime.

Melatonin also contributes to the alleviation of subjective feelings of jet lag under specific conditions of use.

However, more is not necessarily better. Melatonin supplementation changes a biological signal involved in sleep timing, so dose and timing both matter.

3. Glycine

Glycine is an amino acid that has shown promising results in small sleep studies, but the evidence base is still relatively limited.

Glycine is naturally produced by the body and is also obtained through protein-containing foods.

Researchers have investigated supplemental glycine for its potential effects on subjective sleep quality, fatigue and daytime performance following restricted sleep.

Some small human studies have reported improvements in subjective sleep measures after glycine supplementation before bedtime.

However, these studies have generally involved relatively small participant groups, so stronger and larger clinical trials are needed before firm conclusions can be drawn.

Glycine is also interesting in the context of magnesium because magnesium bisglycinate contains magnesium bound to glycine. However, this does not mean that a magnesium bisglycinate supplement necessarily provides the same amount of glycine used in standalone glycine research.

4. L-Theanine

L-theanine may support relaxation and aspects of sleep quality, but research is still emerging.

L-theanine is an amino acid found naturally in tea leaves, particularly green tea.

Unlike a traditional sedative, L-theanine has mainly been researched for its potential influence on relaxation, stress and mental state.

This distinction is important because difficulty sleeping is not always caused by a lack of sleepiness.

For some people, the bigger challenge is feeling mentally alert or unable to switch off at night.

Research into L-theanine and sleep is promising, but the evidence is not currently as established as the biological relationship between melatonin and sleep timing.

5. Vitamin D

Vitamin D status has been associated with sleep outcomes in research, but vitamin D should not be considered a direct sleep supplement.

Vitamin D is best known for its roles in immune function, bones and muscle function.

Research has also explored associations between vitamin D status and sleep quality or sleep duration.

However, an association does not necessarily mean that taking additional vitamin D will improve sleep.

If someone is deficient, correcting inadequate vitamin D status is important for overall health. But taking more vitamin D purely as a sleep aid is not supported in the same way as using a nutrient to address an identified deficiency.

Which Supplement Should You Choose for Better Sleep?

The most appropriate supplement depends on why you are struggling to sleep.

Instead of choosing a product simply because it is marketed for “sleep”, consider the underlying problem.

This is also why combining multiple ingredients without considering their purpose does not necessarily produce better results.

Can Supplements Replace Good Sleep Habits?

No. Supplements can complement a healthy sleep routine, but they cannot compensate for habits that consistently interfere with sleep.

Before focusing exclusively on supplements, consider the fundamentals:

• Keep your sleep and wake times relatively consistent.
• Reduce bright light and screen exposure before bed.
• Avoid caffeine too late in the day.
• Exercise regularly.
• Create a cool, dark and quiet sleeping environment.
• Build a relaxing evening routine.
• Get natural daylight during the morning and daytime.

These behaviours help support the biological systems that regulate sleep and should form the foundation of any sleep routine.

If sleep problems are persistent, severe or affecting your daily life, speak with a healthcare professional rather than relying solely on supplements.

Common Myths About Sleep Supplements

Myth 1: There Is One Best Supplement for Sleep

No.

Different ingredients influence different physiological processes. What is useful for one person may not address the reason another person is struggling to sleep.

Myth 2: Natural Means It Cannot Have Side Effects

No.

Supplements contain biologically active nutrients and compounds. They can have side effects and may interact with medications.

Myth 3: Taking More Will Make the Supplement Work Better

Not necessarily.

Higher doses do not automatically produce better results and may increase the risk of unwanted effects.

Myth 4: Supplements Can Fix Chronic Sleep Problems

Not always.

Persistent sleep problems can have many underlying causes. Supplements should not be used as a substitute for appropriate medical assessment when sleep difficulties continue.

In Summary

There is no single supplement that guarantees better sleep.

Melatonin has one of the clearest established relationships with sleep timing, while magnesium may provide modest benefits for some people – particularly when magnesium intake is relatively low.

Glycine and L-theanine are also interesting areas of research, although the evidence is still developing. Vitamin D, meanwhile, is important for overall health but should not automatically be considered a sleep supplement simply because vitamin D status has been associated with sleep outcomes.

The bigger picture matters most.

A supplement can be one part of your evening routine, but consistent sleep habits, good nutrition, regular movement, daylight exposure and stress management remain the foundation of healthy sleep.

Frequently Asked Questions

What is the best supplement for sleep?

There is no single best sleep supplement for everyone. Melatonin is closely involved in sleep timing, while magnesium, glycine and L-theanine have been studied for other aspects of sleep and relaxation. The most appropriate option depends on the reason for your sleep difficulties.

Does magnesium help you sleep?

Research suggests magnesium supplementation may modestly improve sleep in some people, although the overall evidence is mixed. A 2025 randomised controlled trial specifically investigating magnesium bisglycinate found a small but statistically significant improvement in insomnia symptoms compared with placebo.

Is magnesium or melatonin better for sleep?

They serve different purposes. Melatonin is directly involved in regulating circadian timing and the sleep-wake cycle, while magnesium contributes to normal nervous system and psychological function. Which is more appropriate depends on the individual situation.

Can you take sleep supplements every night?

This depends on the ingredient, dose and your individual circumstances. Follow product instructions and seek professional advice if you take medication, have a medical condition or experience persistent sleep problems.

What vitamins are linked to sleep?

Several nutrients, including magnesium and vitamin D, have been investigated in relation to sleep. However, an association between nutrient status and sleep does not necessarily mean supplementation will improve sleep in someone who already has an adequate intake.

What should I do if supplements do not improve my sleep?

Consider factors such as caffeine, stress, light exposure, sleep schedule and your sleeping environment. Persistent or severe sleep problems should be discussed with a healthcare professional to identify possible underlying causes.

Scientific References

1. Schuster J, Cycelskij I, Lopresti A, Hahn A. (2025). Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep, 17, 2027–2040.
2. Arab A, Rafie N, Amani R, Shirani F. (2023). The Role of Magnesium in Sleep Health: A Systematic Review of Available Literature. Biological Trace Element Research, 201, 121–128.
3. Mah J, Pitre T. (2021). Oral Magnesium Supplementation for Insomnia in Older Adults: A Systematic Review & Meta-Analysis. BMC Complementary Medicine and Therapies, 21, 125.
4. European Commission. EU Register of Nutrition and Health Claims.

This article is for informational purposes only and is not intended to diagnose, treat, cure or prevent any disease. Food supplements should not be used as a substitute for a varied, balanced diet and healthy lifestyle.