What do you know about the research that linked melatonin use to cardiac outcomes?
The study, which has not been published or peer reviewed, looked at retrospective data from adults with insomnia. Its numbers were robust, as it considered 130,000-plus people over five years.
The researchers broke them into two groups – those who took melatonin and those who did not take melatonin. What they found is that individuals who took melatonin had a 90% higher risk of developing heart failure . Additionally, the melatonin users were more than 3.5 times as likely to be hospitalized for heart failure and twice as likely to die from any cause.
Why do people take melatonin?
Melatonin is a hormone released by the body’s pineal gland to regulate the sleep/wake cycle. Melatonin supplements are designed to prime you for sleep – I’ve been told it's like a “burst of darkness.” It’s given to patients in the hospital to help regulate sleep, and it’s often used with success by shift workers – people who work at night and sleep during the day.
People assume melatonin is safe because it’s “natural.” But all supplements need to be treated with respect, just as you would a prescription. It’s important to talk to your doctor before taking any supplement.
What are the limitations of the study?
The people in this study all had insomnia, so we can assume they were experiencing disrupted sleep and taking melatonin to help. There are a few limitations that stand out to me.
The first is something we already know, which is insomnia can be caused by the habits and behaviors people have leading up to sleep. People with poor sleep hygiene are known for taking melatonin hoping it’s an easy fix.
We also know that insomnia can be the result of an underlying sleep disorder. Sleep disorders such as sleep apnea and narcolepsy can increase the risk of heart-related problems, including high blood pressure, heart attacks and death from cardiovascular causes. The American Medical Association estimates that sleep apnea – a condition where breathing is interrupted when you sleep – affects 30 million people. Only about 6 million people are diagnosed, so they estimate 80% of people aren’t aware they have a problem.
This study didn’t look at comorbidities, so we don’t know if these patients had other medical conditions that were impacting their heart. We also don’t know the dosage of the melatonin they were taking or other medications they were taking in addition to the melatonin. Because of this, we can’t associate the cardiac outcomes these patients experienced based on melatonin supplementation alone.
"I suspect we may find that melatonin use is a marker – a confounder. It’s similar to saying that people who smoke cigarettes and drink coffee are more likely to get lung cancer. The coffee is a marker, not the cause of lung cancer." – Robert Page, PharmD, MSPH
What can we take away from this study?
Well first, if you’re taking melatonin, don’t panic. I suspect we may find that melatonin use is a marker – a confounder. It’s similar to saying that people who smoke cigarettes and drink coffee are more likely to get lung cancer. The coffee is a marker, not the cause of lung cancer.
If you are taking melatonin for sleep, let this be a wake-up call to talk to your doctor – not because you’re using melatonin but because you need to be evaluated for sleep disorders and learn more about improving sleep hygiene.
Finally, no supplement is 100% safe. Anytime you take over-the-counter melatonin or any supplement, take it at the lowest dose possible.
How to Improve Sleep Hygiene
There are many things you can do to improve your habits and behaviors surrounding sleep, says board-certified sleep expert Jessica Camacho, MD, assistant professor of internal medicine at CU Anschutz.
“First, it’s important to have consistent sleep and wake times, every day. Make sure you’re sleeping in a cool, comfortable space. Stop using electronics in bed, and don’t use screens an hour before you sleep. Avoid excess alcohol and caffeine and get enough exercise. These aren’t quick fixes to great sleep – they are hard work. But they can greatly improve your sleep quality if used consistently,” Camacho said.
Key points:
- A study found adults with insomnia who used melatonin for a year or longer were reported to have a higher risk of heart failure than those who did not.
- The research showed an association but not cause and had clear limitations, including not accounting for participants’ other health conditions, medications and melatonin dosage.
- Persistent insomnia can signal another health problem, and people experiencing ongoing sleep difficulties should talk to their doctor.
- Experts recommend consistent sleep and wake times, limiting electronics before bed, keeping the bedroom cool, exercising, and avoiding excessive caffeine and alcohol.
