What Happens to Your Body When You Take Melatonin Every Night

Quick answer: Taking melatonin every night may help you fall asleep sooner, but it can also cause daytime sleepiness, headaches, dizziness, nausea, or changes in your dreams. Short-term use appears safe for most adults, but there’s less information about what happens when melatonin is taken every night for months or years. 

You’ve probably taken a melatonin supplement at some point, hoping it would help you get a better night’s sleep.

Melatonin is a hormone your body naturally produces that helps regulate your sleep-wake cycle. But the melatonin found in most gummies, pills, sprays, and liquids is a lab-made version of the hormone sold as a dietary supplement. 

Some people take melatonin for jet lag, while others end up taking it before bed every night. So what happens when melatonin becomes part of your nighttime routine?

What happens when you take melatonin every night?

The effects of taking melatonin every night can differ from person to person.

You may notice:

• You fall asleep sooner

• You feel sleepy or groggy the next morning

• Your sleep schedule changes

• You get headaches or feel dizzy

• You feel nauseous or have an upset stomach

• You have vivid dreams or nightmares

While most side effects reported in short-term studies have been mild, they can still affect how you feel during the day. 

Here’s what each of these can look like.

1. You may fall asleep sooner

Melatonin can help some people fall asleep faster, especially when their body clock is out of sync.

Jet lag is a good example. After traveling across several time zones, your internal clock may no longer match the local time. Melatonin may help reduce jet lag symptoms and improve sleep. 

Melatonin is also used for delayed sleep-wake phase disorder, a condition that makes it difficult to fall asleep at the usual time and wake up in the morning. Studies have found that melatonin can shorten the time it takes people with this condition to fall asleep. [1] 

There also isn’t strong enough evidence to recommend melatonin as a routine treatment for chronic insomnia in adults. Pain, stress, depression, sleep apnea, restless legs, and other health problems can also interfere with sleep, and melatonin may not address what’s causing those problems.

2. You could still feel sleepy the next morning

Melatonin is supposed to make you sleepy, but for some people that feeling lasts into the next day. 

You may wake up groggy, tired, or have a harder time staying alert. Daytime sleepiness is one of the most commonly reported side effects of melatonin. The dose and timing can play a role. Taking melatonin very late at night gives your body less time to clear it before morning.

Older adults may also feel its effects for longer because melatonin can stay active in their bodies longer than it does in younger adults. 

3. Your sleep schedule may shift

Melatonin helps control when your body expects sleep to happen. Taking extra melatonin can shift your sleep-wake cycle, which is one reason it can help with jet lag and some circadian rhythm sleep disorders.

But the time you take it also affects how it works. Taking melatonin at different times from one night to the next may change when you start feeling sleepy.

This is different from simply making you drowsy. Melatonin is also sending your body a signal about when nighttime should begin.

4. You may get headaches or feel dizzy

Headaches and dizziness are known side effects of melatonin. The reason some people develop headaches after taking melatonin isn’t always clear.

Having a headache after taking it also doesn’t necessarily mean melatonin caused it. You might be dehydrated, sleeping poorly, dealing with migraine, or have another sleep problem such as sleep apnea.

Dizziness can happen as well. If you already tend to feel light-headed or take medication for hypertension, talk with your healthcare provider before using melatonin regularly.

5. Your stomach may feel upset

Melatonin can cause nausea and stomach discomfort in some people. Abdominal cramps have also been reported.

Other ingredients used to make melatonin supplements may upset your stomach too. 

Gummies and flavored liquids can contain sweeteners, flavorings, dyes, sugar alcohols, and other inactive ingredients. If one product bothers your stomach more than another, it may be worth checking the full ingredient list.

Also Read: Tart Cherry Juice vs. Melatonin Pills: Which Works Better for Sleep?

6. You may have vivid dreams or nightmares

You might notice unusually vivid dreams or nightmares after taking melatonin.

It isn’t completely clear whether melatonin itself directly causes them. One possible explanation involves REM sleep, the stage of sleep when vivid dreaming is most common. Melatonin may increase REM sleep in some people, which could make vivid dreams more noticeable. [2]

Stress and anxiety can affect your dreams too. Certain medications and sleep disorders, including obstructive sleep apnea, have also been linked with vivid dreams or nightmares. Research has not yet shown exactly how melatonin affects dreams.

Less common side effects of melatonin

Melatonin can cause other side effects too, although they’re reported less often.

These may include:

• Temporary feelings of depression

• Mild anxiety

• Abdominal cramps

• Irritability

• Reduced alertness

• Confusion or disorientation

• Low blood pressure

These effects are less common than daytime sleepiness, headache, dizziness, and nausea. 

If a side effect becomes severe, doesn’t go away, or starts interfering with your daily life, talk with a healthcare provider.

Can you overdose on melatonin?

While melatonin is generally well tolerated, taking too much can still cause problems. 

There isn’t one dose that doctors consider an overdose for everyone. Higher amounts are more likely to cause side effects such as sleepiness, headache, dizziness, and nausea.

Children and teenagers are also at risk for accidental or intentional melatonin overdose. From 2012 to 2021, U.S. poison control centers received more than 260,000 reports involving melatonin ingestion in people age 19 and younger. Most involved young children who accidentally took melatonin at home, but hospitalizations and more serious outcomes also increased during that period. Intentional overdoses were more common among teenagers who were hospitalized. [3]

A later CDC report estimated about 11,000 emergency department visits from 2019 through 2022 for unsupervised melatonin ingestion among children age 5 and younger. Flavored products such as gummies were involved in many cases. [4]

If someone takes much more melatonin than intended and becomes difficult to wake, confused, has trouble breathing, or develops another severe symptom, seek medical care.

Also Read: Is Melatonin Safe Long-Term? A Sleep Physician Explains

Is melatonin addictive?

Melatonin isn’t generally considered addictive in the way benzodiazepines and some prescription sleeping medications can be.

Research hasn’t shown the same pattern of physical dependence that can happen with those drugs. Studies of prolonged-release melatonin have also found little evidence of tolerance or withdrawal after stopping it. [5] 

However, it is still possible to develop a psychological reliance on melatonin. This can happen if you take it every night and begin to feel incapable of sleeping without it.

If your sleep worsens after you stop taking melatonin, it may indicate that the underlying sleep issues that prompted you to start using it are still present. This situation is not necessarily the same as experiencing withdrawal. 

Also Read: Melatonin Withdrawal: Is It Real, and What Happens When You Stop Taking It?

So, is it OK to take melatonin every night?

Melatonin supplements are generally considered safe and well tolerated by most people when used for a short period of time.

The most common side effects include daytime sleepiness, headache, dizziness, and nausea. Less common effects can include vivid dreams or nightmares, irritability, mild anxiety, stomach cramps, and reduced alertness. 

There’s less information about taking melatonin every night for months or years, so its long-term effects are still not fully known. If your side effects become serious or don’t go away, or if you feel like you need melatonin every night to sleep, talk with your healthcare provider.

And if you’d rather not rely on a synthetic melatonin supplement every night, Sip2Sleep® is worth a try. It’s a physician-made natural sleep aid made with two natural ingredients, Montmorency tart cherry extract and Rafuma leaf, with no added synthetic melatonin.

About the author

Dr. Ruchir P. Patel, MD, FACP, is the Medical Director of the Insomnia and Sleep Institute of Arizona and the founder of Sip2Sleep. He is triple board-certified in sleep medicine, obesity medicine, and internal medicine. Dr. Patel is a multi-year Phoenix Magazine Top Doctor and holds the Inspire Excellence designation.

Reference

1. Costello, R. B., Lentino, C. V., Boyd, C. C., O'Connell, M. L., Crawford, C. C., Sprengel, M. L., & Deuster, P. A. (2014). The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature. Nutrition journal, 13, 106. https://doi.org/10.1186/1475-2891-13-106

2. Kunz, D., Mahlberg, R., Müller, C., Tilmann, A., & Bes, F. (2004). Melatonin in patients with reduced REM sleep duration: two randomized controlled trials. The Journal of clinical endocrinology and metabolism, 89(1), 128–134. https://doi.org/10.1210/jc.2002-021057

3. Lelak, K., Vohra, V., Neuman, M. I., Toce, M. S., & Sethuraman, U. (2022). Pediatric melatonin ingestions — United States, 2012–2021. Morbidity and Mortality Weekly Report, 71(22), 725–729. https://doi.org/10.15585/mmwr.mm7122a1

4. Freeman, D. I., Lind, J. N., Weidle, N. J., Geller, A. I., Stone, N. D., & Lovegrove, M. C. (2024). Notes from the field: Emergency department visits for unsupervised pediatric melatonin ingestion — United States, 2019–2022. Morbidity and Mortality Weekly Report, 73(9), 215–217. https://doi.org/10.15585/mmwr.mm7309a5

5. Lemoine, P., Garfinkel, D., Laudon, M., Nir, T., & Zisapel, N. (2011). Prolonged-release melatonin for insomnia - an open-label long-term study of efficacy, safety, and withdrawal. Therapeutics and clinical risk management, 7, 301–311. https://doi.org/10.2147/TCRM.S23036