Melatonin for cancer patients: Is it safe?

If you’ve ever struggled with insomnia, you’ve likely heard of melatonin. This nutritional supplement has been widely available in drug stores, health food stores and grocery stores for years, and touted as a natural sleep aid. It even comes in doses meant for children.

But what is melatonin? And is it safe for cancer patients to take during treatment?

We checked in with pulmonologist Saadia Faiz, M.D., for answers.

What is melatonin?

Melatonin is a hormone that’s produced naturally by the body. It’s secreted by the pineal gland, which is located deep inside the brain. It’s thought to help regulate the sleep cycle.

How does melatonin work?

The exact mechanism is not really understood, but melatonin is thought to promote sleep by controlling the circadian rhythm, the natural, 24-hour sleep/wake cycle that many creatures have.

The pineal gland’s secretion of melatonin is directly tied to the length of the night. Normally, melatonin levels rise as darkness falls, then stay high and steady during the night, and drop again as dawn breaks or people are exposed to bright light.

Where do melatonin supplements come in?

The melatonin in supplements, such as gummies or pills, is usually made in a lab, as opposed to derived from natural sources.

Typically, they are taken a few hours before bedtime. And some clinical studies suggest that melatonin supplements may help users fall asleep more quickly and increase the amount of time they spend asleep.

However, there is controversy about the use of these supplements for insomnia. And the American Academy of Sleep medicine does not recommend the use of melatonin supplements for the treatment of insomnia, due to unanswered questions about appropriate dosage, contamination and lack of regulation of over-the-counter preparations.

Is one type of melatonin product better, more effective or more quickly absorbed than others?

Not necessarily. A product’s effectiveness more likely depends on its concentration of melatonin, rather than its form.

One major limitation of over-the-counter supplements is that they are not regulated by the Food and Drug Administration (FDA), so the amount of melatonin contained in each supplement is unclear. For those using melatonin, I would at least make sure the product is labeled as “USP Verified,” which indicates that the formulation meets the requirements of the U.S. Pharmacopeial Convention.

Is melatonin addictive?

Not to the best of our knowledge. But, again, no long-term studies are available.

Is it safe for patients to use melatonin during cancer treatment?

Melatonin is generally regarded as safe. But data on long-term and high-dose use are scarce.

That’s why we strongly recommend talking to your health care team before taking any supplements — including melatonin — because they could potentially interact with your other medications and affect how they work.

Sleep disturbances are a common problem among those undergoing cancer treatment. Insomnia involves difficulties with falling asleep, staying asleep or waking up earlier than desired. For people with short term insomnia, adopting healthy sleep habits and promoting sleep hygiene may be more helpful than a supplement. For people with chronic insomnia, cognitive behavioral therapy is the recommended treatment. In any event, referral to a sleep specialist would be recommended first for anyone with insomnia or some other sleep issue.

What are the side effects of melatonin?

Side effects are very rare. They occur in less than 2% of cases and may include:

• daytime sleepiness
• headache
• dizziness
• hypothermia (low body temperature)

It’s important to keep in mind that daytime sleepiness can also be a symptom of some advanced cancers, though, which disrupt sleep cycles by reducing the normal secretion of melatonin.

Are there any reasons why someone shouldn’t use melatonin during cancer treatment?

No. But again, we encourage patients to discuss all of their medications — including over-the-counter and herbal supplements — with their oncologists.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.