Is It Safe to Take Melatonin Every Night? (UK Guide)

Melatonin is one of the most widely used sleep aids globally, but is it safe to take every night?

And how does that apply to the UK, where melatonin is only available via prescription?

This guide answers those questions and more, drawing on up-to-date research, UK-specific regulations, and practical insights for anyone struggling with sleep.

What Is Melatonin?

Melatonin is a hormone naturally produced by the pineal gland in the brain. It plays a key role in regulating your circadian rhythm — the body’s internal clock that dictates sleep-wake cycles. Melatonin levels typically rise in the evening, making you feel drowsy, and fall again in the morning.

Supplemental melatonin is designed to mimic this effect, often used to help with:

• Jet lag

• Shift work sleep disorder

• Delayed sleep phase disorder

• General insomnia (in some cases)

In countries like the US and Canada, melatonin is sold over the counter. But in the UK, it's classified as a prescription-only medicine (POM).

Is Melatonin Available Over the Counter in the UK?

No. As of 2025, melatonin is not legally available over the counter in the UK. It is classified by the MHRA (Medicines and Healthcare products Regulatory Agency) as a prescription-only medication.

NHS guidance generally restricts melatonin prescriptions to short-term use in specific populations, such as:

• Children and adolescents with sleep disorders related to conditions like ADHD or autism

• Adults over 55 with primary insomnia (for up to 13 weeks)

Some private clinics and online pharmacies may offer melatonin, but this should only be done under medical supervision.

Is It Safe to Take Melatonin Every Night?

This depends on several factors, including dosage, duration, age, and whether the supplement is being taken under medical advice.

Short-Term Safety

Most studies agree that short-term use of melatonin is generally safe for most people. Side effects are usually mild and may include:

• Drowsiness

• Dizziness

• Headaches

• Nausea

The NHS and NICE both support limited-duration use in appropriate cases, especially among older adults or those with circadian rhythm sleep disorders.

Long-Term Safety: What the Research Says

The long-term safety profile of melatonin is still being studied. However, a 2022 systematic review published in Sleep Medicine Reviews found that long-term use (up to 12 months) in both children and adults did not show serious adverse effects. That said, the authors also emphasised the need for more high-quality research.

There are concerns that long-term, nightly use of melatonin might:

• Suppress natural melatonin production

• Disrupt hormonal development (especially in children)

• Interfere with reproductive hormones

• Lead to dependency or psychological reliance

Although melatonin is not considered addictive, the idea of 'needing' a pill to fall asleep can lead to behavioural dependence.

How Much Melatonin Is Too Much?

Melatonin dosage can vary wildly across products and countries. In the UK, prescribed doses typically range from 2 mg (prolonged release) to 5 mg, taken one hour before bed.

In contrast, many American supplements contain 10 mg or more — well above what most experts recommend.

Research from the Journal of Clinical Sleep Medicine shows that lower doses (0.5 to 3 mg) are often just as effective and carry fewer side effects. Taking more does not necessarily mean better sleep and could backfire by causing daytime drowsiness or hormonal disruption.

Should Melatonin Be Used as a Long-Term Solution?

Melatonin is best used as a short-term aid or for specific sleep conditions like delayed sleep phase disorder or shift work disorder. The NHS does not recommend indefinite use. Instead, it’s most effective when combined with behavioural strategies, such as:

• Maintaining a consistent sleep schedule

• Reducing screen exposure before bed

• Managing caffeine and alcohol intake

For those with chronic insomnia, cognitive behavioural therapy for insomnia (CBT-I) is the gold standard treatment, as recommended by NICE.

According to, Dr. Ana Krieger, medical director of the Center for Sleep Medicine at Weill Cornell Medicine and NewYork-Presbyterian:

"Relying on melatonin supplements alone without optimizing your nighttime habits, is often not the best approach."

When Might Long-Term Melatonin Use Be Justified?

There are some medical contexts where longer use may be considered appropriate under supervision:

• Adults with neurodegenerative conditions (e.g., Alzheimer’s disease)

• Children with neurodevelopmental disorders and sleep difficulties

• Individuals with non-24-hour sleep-wake disorder (often seen in the blind)

Even in these cases, regular monitoring and reassessment are key.

Natural Alternatives to Melatonin

For those seeking a non-hormonal sleep aid, the following options may offer support:

• Magnesium: Promotes relaxation and reduces cortisol levels. See our full blog on magnesium for sleep.

• Valerian root: A herbal remedy with sedative effects, commonly used in the UK.

• Glycine: An amino acid shown to lower core body temperature and support sleep onset.

• L-theanine: An amino acid from green tea that promotes relaxation without sedation.

These alternatives can often be taken long-term with fewer risks than melatonin, but they still benefit from a conversation with a healthcare provider.

Melatonin vs. Other Sleep Aids: A Safety Comparison

Sleep Aid	Type	Available in UK OTC?	Safe for Nightly Use?
Melatonin	Hormone	No	Possibly, with medical advice
Magnesium	Mineral supplement	Yes	Yes (generally safe)
Valerian Root	Herbal remedy	Yes	Likely safe, but can cause drowsiness
Diphenhydramine	Antihistamine	Yes	Not recommended long-term
Glycine	Amino acid	Yes	Yes
L-theanine	Amino acid	Yes	Yes

Melatonin is often seen as more 'natural' than prescription sleeping tablets, but it's still a hormone, meaning it affects the body's endocrine system. For that reason, regular long-term use without guidance is not advisable.

Final Verdict: Is It Safe to Take Melatonin Every Night?

In the UK, melatonin is a prescription-only medication for a reason: it can be safe when used correctly, but it is not risk-free. Occasional or short-term use under medical supervision is generally well-tolerated. However, nightly, long-term use should be approached cautiously.

Those struggling with persistent insomnia or circadian rhythm issues should speak to a GP or sleep specialist. Alternatives like magnesium, glycine, or CBT-I may offer more sustainable results.

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Frequently Asked Questions

Can I get melatonin online in the UK?

Only through licensed online pharmacies with a prescription. Be wary of unregulated imports.

Is melatonin addictive?

Can children take melatonin?

What’s the best time to take melatonin?

Is it OK to take melatonin for jet lag?