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Melatonin Side Effects: Is It Safe for Long-Term Use?

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March 13, 2025

Melatonin Side Effects: Is It Safe for Long-Term Use?

Medically reviewed by: 

Dr. Areti Vassilopoulos

Yale School of Medicine

Introduction

Melatonin is widely used as a natural sleep aid, helping millions of people fall asleep faster and improve their sleep quality. However, many users wonder whether melatonin is safe for long-term use and what side effects it may have. In this article, we'll explore the potential risks and benefits of melatonin, its impact on the body, and safer alternatives for better sleep.

How Does Melatonin Work?

Melatonin is a hormone naturally produced by the pineal gland in response to darkness, signaling to the body that it's time to sleep. Melatonin supplements aim to mimic this natural process, making it easier for individuals with insomnia or disrupted sleep patterns to fall asleep. However, supplementing with melatonin regularly may interfere with the body's ability to produce its own melatonin naturally.

Melatonin also affects the body's circadian rhythm, which regulates sleep-wake cycles. When melatonin levels are disrupted, individuals may experience difficulties in maintaining a consistent sleep schedule. Learn more about melatonin and circadian rhythm.

Common Side Effects of Melatonin

1. Daytime Drowsiness

One of the most frequently reported side effects of melatonin is daytime drowsiness. Some individuals feel groggy the next morning, which can interfere with daily activities. Studies suggest that taking melatonin at the wrong time or in high doses may contribute to lingering drowsiness.

2. Hormonal Effects

Melatonin can influence hormonal balance, potentially affecting reproductive health, especially in women. Some studies suggest that high doses of melatonin may impact estrogen and testosterone levels, leading to menstrual irregularities and fertility concerns. Read about melatonin's effects on reproductive health.

3. Mood Changes

Some users experience mood swings, mild depression, or increased anxiety after prolonged melatonin use. Because melatonin plays a role in regulating mood, excessive supplementation could disrupt natural serotonin and dopamine levels.

4. Gastrointestinal Issues

Melatonin supplements may cause stomach discomfort, nausea, or diarrhea in some individuals. Adjusting the dosage or taking melatonin with food may help reduce these side effects.

5. Disrupted Sleep Cycle

While melatonin is commonly used to improve sleep, incorrect use may lead to disrupted sleep patterns. Taking melatonin too frequently or at inappropriate times could cause dependence on the supplement, leading to difficulties falling asleep without it.

Is Melatonin Safe for Long-Term Use?

While melatonin is generally considered safe for short-term use, its long-term effects are not fully understood. Some research suggests that prolonged melatonin supplementation could desensitize melatonin receptors, making it harder for the body to regulate sleep naturally.

Studies have also linked long-term melatonin use to a potential increase in oxidative stress in the brain, leading to concerns about cognitive decline. Read about melatonin and brain health.

Potential Long-Term Risks:

           
  • Reduced natural melatonin production
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  • Increased tolerance leading to higher doses over time
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  • Potential interactions with medications, including blood thinners and antidepressants
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  • Increased risk of hormonal imbalances
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Safer Alternatives to Melatonin

If you are looking for a long-term sleep solution that does not rely on supplements, consider the following alternatives:

           
  • Cognitive Behavioral Therapy for Insomnia (CBT-I): A highly effective treatment that addresses the root causes of sleep problems without medication. Learn more
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  • Natural Sleep Aids: Magnesium, valerian root, and chamomile may help improve sleep quality naturally. Read about natural sleep aids.
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  • Optimized Sleep Hygiene: Maintaining a consistent sleep schedule, reducing blue light exposure before bed, and creating a relaxing nighttime routine can significantly improve sleep.
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Better Sleep with Sleep Reset

At Sleep Reset, we help you achieve quality sleep without dependency on supplements. Take our sleep quiz to identify the root causes of your sleep issues and receive personalized guidance.

Our expert-designed sleep program uses CBT-I principles to help you improve your sleep naturally. Our program does not rely on melatonin or prescription sleep aids, ensuring long-term, sustainable sleep improvements.

With Sleep Reset, you'll receive a customized sleep plan and guidance from dedicated sleep coaches. If you're struggling with sleep, let us help you achieve the restorative rest you deserve.

Conclusion

Melatonin can be a helpful short-term sleep aid, but its long-term safety remains uncertain. Instead of relying on supplements, consider alternative approaches such as CBT-I, improving sleep hygiene, and utilizing Sleep Reset's science-backed sleep programs. Prioritizing natural and sustainable sleep solutions will lead to better health and improved well-being in the long run.

Dr. Areti Vassilopoulos

Dr. Vassilopoulos is the Clinical Content Lead for Sleep Reset and Assistant Professor at Yale School of Medicine. She has co-authored peer-reviewed research articles, provides expert consultation to national nonprofit organizations, and chairs clinical committees in pediatric health psychology for the American Psychological Association. She lives in New England with her partner and takes full advantage of the beautiful hiking trails.