Getting a good night’s sleep is essential to our physical and mental health. But when you can’t seem to fall asleep or stay asleep, it’s tempting to reach for melatonin supplements to help the process along. 

Wondering if melatonin supplements put you at risk for health problems is a fair question, especially if you have heart failure. 

The difference between natural melatonin and supplements

Melatonin is a hormone naturally produced in the brain in response to darkness. While the body produces melatonin on its own, factors like exposure to light at night, stress or digital device use can disrupt your internal clock. Melatonin supplements, on the other hand, are made either by extracting the hormone from animals or by synthesizing it through a chemical process.

The FDA does not regulate melatonin supplements sold in the United States. This means they are not held to the same safety or approval process as medications.

The melatonin use and heart failure study

A recent study sought answers to the question of melatonin use and a higher risk of heart failure. Researchers looked at the electronic medical records of 130,000 adults with chronic insomnia who had the same health factors. They compared adults who took melatonin supplements for a year or more with those who did not.  

Did the participants taking melatonin have a higher chance of heart failure or be more likely to be hospitalized for it? The answer isn’t clear, as the study itself had significant limitations. Researchers didn’t have details on insomnia severity, mental health issues, melatonin dosage or whether they used prescription or over-the-counter supplements.  

“The abstract reported by the American Heart Association was based on this study’s retrospective chart review,” says advanced heart failure and transplant cardiology fellow Jennifer Nickol, DO. “What it showed was an association between melatonin use and heart failure, not causation, or a cause and effect. It’s important that we don’t jump to conclusions about melatonin causing heart failure based on this type of study design.” 

Patients with heart failure often have difficulty sleeping due to their condition. This may make them more likely to be prescribed melatonin more frequently. 

“This association does not necessarily mean melatonin is causing heart failure,” adds Dr. Nickol. “While some studies have suggested melatonin may have a slight blood pressure lowering effect, clinical evidence is not yet conclusive. There is no clear evidence that melatonin is unsafe for heart failure patients specifically. More research is needed to fully understand melatonin's cardiovascular effects.”

A noteworthy aside: The study was not designed to prove a link, and contradicts previous studies that suggested potential benefits for heart health. The study has not yet been published.

Melatonin safety

Melatonin is generally considered safe. Dr. Nickol recommends that heart failure patients use the lowest effective dose for the shortest duration. Melatonin supplements shouldn’t be taken for long periods without a health care provider’s oversight. The general recommendation for over-the-counter melatonin is one milligram each night.

Some people notice side effects such as:

• Headaches.
• Nausea or stomach aches.
• Dizziness or drowsiness.
• Confusion or irritability.

“As to melatonin’s side effects, we suspect that it affects older people more than young people because of the way metabolism works as you age,” says Dr. Nickol. “But so far, with the data that we have, I think that there is more evidence to show melatonin safety than evidence to show clear harm.”

If you have heart failure, discuss melatonin use with your doctor

Dr. Nickol advises that all patients with a heart problem who are dealing with insomnia should discuss starting melatonin or any new supplement with their doctor. If insomnia is chronic, perhaps a closer look to see if there’s another reason for the sleep difficulty is warranted.

“A discussion is always a good idea due to potential interactions with certain medications like blood thinners and blood pressure drugs,” adds Dr. Nickol. “However, I wouldn’t use a retrospective study such as this to discourage melatonin use. If you feel you need long-term use of melatonin, like having to take it every night, then it's probably best to speak with your doctor about other options to help with your sleep.”