Side Effects of Melatonin for Sleep

The hormone melatonin is important for a good night’s sleep, but there may be side effects. Taking melatonin for sleep is thought to be natural by some people because it’s secreted in tiny amounts from the pineal gland in your brain. But, others caution against taking too much melatonin for sleep.

Here’s a summary of what melatonin is, how it affects sleep, and the side effects of taking melatonin to sleep better. Since melatonin regulates the sleep-wake cycle, it can be an effective remedy for jet lag. Melatonin supplements should only to be used as a short-term solution to sleep problems, not a long-term sleep remedy.

What is Melatonin?

As each day draws to a close and darkness starts to fall, the hormone melatonin increases in our bodies. This is the optimal circumstance, anyway – sometimes our bodies don’t produce enough melatonin, which leads to problems sleeping or insomnia. Some people take melatonin for sleep, despite the possible side effects, because the supplemental melatonin increases the natural production of this sleep hormone.

Most of the time, melatonin is produced in a predictable daily rhythm by the pineal gland, which is located between the two hemispheres of the brain. Sleep doctors believe melatonin’s daily light-sensitive cycle helps keep the sleep/wake cycle on track – and large doses of melatonin can make us sleepy.

Causes of low melatonin levels

Melatonin production is disrupted in people who work shifts at night, have newborn babies or kids who are light sleepers, or who travel a lot. Another reason for low “sleep hormone” levels is electricity! We stay up long after the sun goes down and darkness falls, and this confuses our bodies. Our pineal glands think they should be producing melatonin because it’s dark outside, but the lights are blazing inside.

side effects melatonin sleep hormone

“Side Effects of Melatonin for Sleep” image by Peter Vilhelm

Low melatonin levels make it hard to fall asleep at night – which means a natural sleep remedy is to keep your lights low low low before going to bed at night. Try candlelight, especially if you’re hoping to spice up your love life a little.

Another reason our bodies don’t produce enough of this sleep hormone is age. Some people over the age of 65 have melatonin levels so low that they can’t sleep at all at night. Elderly people sleep less not because they need less sleep, but because their bodies aren’t producing enough melatonin for sleep. The side effects of melatonin for elderly people are different than younger people, which further complicates matters.

Melatonin and tamoxifen for breast cancer

Here’s a brief side note on melatonin, sleep, and women with breast cancer:

Research from Tulane University shows that low or no melatonin levels makes tamoxifen  (a widely used breast cancer drug) ineffective. Exposure to light at night shuts off the production of this sleep hormone, which in turn makes breast cancer resistant to tamoxifen. Melatonin by itself delayed the formation of breast cancer tumors and significantly slowed their growth. When melatonin levels are high because of darkness or melatonin supplements, tamoxifen caused a dramatic regression of tumors. But when melatonin levels are low, the cancer drug was ineffective.

These findings do NOT mean women who are taking tamoxifen for breast cancer should also take melatonin for sleep! Better is to make sure you encourage your body to produce melatonin naturally, such as by not exposing yourself to bright lights at night and by learning about natural sleep remedies that don’t involve supplements.

Possible Side Effects of Melatonin for Sleep

Before you take melatonin for sleep, eliminate all other possible causes of insomnia. Don’t take melatonin supplements unless you know your body isn’t producing enough of this sleep hormone.

Grogginess and dizziness for some people

“Melatonin has repeatedly been shown to be completely free of side effects when used as directed,” write Mindell and Hopkins in Prescription Alternatives. They add that melatonin isn’t addictive (unlike prescription sleeping pills). However, my research shows that melatonin supplements can be psychologically addictive. This means that people build up an emotional dependency and believe they can’t sleep without taking melatonin.

I took melatonin to help me recover from jet lag the last time I went to Europe, and I felt groggy and nauseous all the next day. I think I took too much – even though it was “only” one table of melatonin. How many milligrams of melatonin were in that tablet? That’s what I didn’t pay attention to, and it cost me a whole day in Vienna. If you’re taking melatonin for the first time, make sure you start small.

Most common side effects of melatonin

Sleep doctors disagree with people who claim there are no side effects of melatonin. “The most commonly reported side effects are nausea, headache, and dizziness,” writes Dr Lawrence Epstein in A Good Night’s Sleep. “Melatonin’s long-term side effects are unknown.”

The side effects of melatonin supplements depend on who is taking it – their body weight, genetic makeup, natural production of this sleep hormone, etc. My husband can take melatonin supplements to overcome jet lag and be perfectly alert the next day.

If you’re reluctant to take melatonin for sleep because of the possible side effects – or because you’re taking prescription medications that may interact with the sleep hormone – consider Bigelow Sweet Dreams Herbal Tea. It’s a calming, relaxing herbal blend of chamomile, peppermint, rose blossoms, spearmint, spices, and orange blossoms. It’s worth trying because it won’t affect your natural sleep hormones.

If you want to try melatonin for sleep, remember that it only takes a very small dose to help you fall asleep. It’s also very important to determine why you can’t sleep. If low levels of this sleep hormone aren’t your problem, then you could take a whole bottle of melatonin supplements and still not fall asleep! But of course the side effects of that much melatonin are not good – so don’t do it.

Long-term side effects of melatonin for sleep

Doctors don’t know what the long-term side effects of melatonin for sleep are, which means you shouldn’t take it every night. When we take any type of hormone in higher doses than our bodies naturally produce, we are setting ourselves up for imbalances.

“It is perfectly safe to take melatonin for an occasional bout of insomnia,” write Mindell and Hopkins. “Melatonin is a natural hormone, so when it is used occasionally your body should have no trouble excreting any excess.”

A Melatonin Supplement for Sleep

NOW Foods Melatonin 5mg Tablets is the most popular melatonin sleep supplement on Amazon, and has very positive reviews by users. According to the makers, melatonin for sleep may be associated with the regulation of normal sleep/wake cycles. Further, melatonin is a potent antioxidant that defends against free radicals and helps support glutathione activity in neural tissues.

Look for a reputable brand before you buy melatonin for sleep, and make sure you get a pharmaceutical grade of melatonin. Take melatonin tablets about one hour before you want to fall asleep, and give yourself at least eight hours of sleeping time.

It only takes a small dose of melatonin to help you sleep better – and the smaller the dosage, the less disruptive any possible side effects of melatonin will be. Always talk to your doctor before taking any natural herbal supplement, and ask him or her about side effects of melatonin for sleep.

If you have any thoughts or questions on the side effects of melatonin for sleep, please comment below. I’m not a sleep doctor, but I’m a good researcher. I’m happy to try to find the answers to your questions about this sleep hormone.

Resources: 1) Tulane University. Total darkness at night key to success of breast cancer therapy, study shows; and 2) Prescription Alternatives by Earl Mindell and Virginia Hopkins.  

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