The short answer
For most adults, melatonin is not bad for you when you use a low dose for a clear reason. It is a hormone your body already makes. Short term use appears safe for most adults, and the most common side effects are mild, like daytime drowsiness or a headache.2,6
The honest part: we do not have strong data on many years of nightly use.2 A 2025 study linked long term melatonin records to heart failure, but it could not show that melatonin caused it.1 That is a reason to use the lowest dose that works, with a plan, not a reason to panic.
What people are really asking
Friends and patients ask me all the time if melatonin is safe. I tell them the same thing every time. Melatonin is a natural hormone your body makes every night. The trouble usually starts when people take far more than their body would ever make on its own.
So the better question is not "is melatonin bad?" It is "how much am I taking, and why?" Many products on store shelves hold 5 mg to 10 mg. In a study of adults over 50, just 0.3 mg was enough to bring night levels back to normal, while 3 mg pushed levels far higher, into the next day.5
The 2025 heart study: what it found, and what it could not show
In November 2025, researchers presented a study at the American Heart Association's yearly meeting. It looked at the health records of about 130,000 adults with insomnia. The average age was about 56, and most were women.1
What it found
- People whose records showed melatonin for a year or more were more likely to be diagnosed with heart failure over 5 years.
- 4.6% in the melatonin group, compared with 2.7% in the group without it.1
What it could not show
- It could not prove melatonin caused heart failure. The lead researcher said so.1
- It only counted melatonin written in medical records. Many people who buy it at the store would have been counted as not taking it.
- It did not know the dose, or how bad each person's insomnia, stress, or depression was.1
- It was a meeting presentation, not yet a full published study.
My reaction as a nurse: we always have to be careful with anything we put into our bodies, and we should know why we are taking it. A single study like this one is not built to give the final answer. So I keep an open mind, I watch for better research, and I lean toward the lowest dose that does the job.
If you have heart disease, or heart failure runs in your family, talk to your doctor before you use melatonin, and bring this study up. I walk through all of the numbers in melatonin and heart failure: what the 2025 study found.
Is it safe to take melatonin every night?
Many people take melatonin every night for a few weeks or months. The US National Center for Complementary and Integrative Health says melatonin appears safe for most adults short term, but that information on long term safety is lacking.2
Some of the longest studies used a 2 mg slow release form in adults 55 and older. People took it for up to 6 to 12 months, and the researchers did not see withdrawal or rebound sleep trouble when they stopped.3,4
When someone tells me they take melatonin every night with no plan to stop, here is what I say. Your body already makes melatonin every night. If you take a low dose and it is working, I do not see a big problem with that. But only take what is actually working for you, and do not count on melatonin alone.
That last part matters most. Melatonin is a timing signal, not a sleeping pill. That is why the American Academy of Sleep Medicine does not recommend it as a treatment for chronic insomnia on its own.11 For long term sleep trouble, doctors recommend cognitive behavioral therapy for insomnia, often called CBT for insomnia, as the first step.10
Can you build a tolerance to melatonin?
There is little sign that melatonin works like sleeping pills, where you need more and more over time. In the long term studies above, people did not have withdrawal when they stopped.3,4
If melatonin seems to stop working, the cause is usually something else: taking it at a different time each night, bright screens before bed, stress, alcohol, or night sweats. Taking more is rarely the fix. A higher dose can leave you groggy the next day. I explain why in why you feel groggy after melatonin.
Side effects to know
Mayo Clinic lists these as the most common side effects:6
- Daytime drowsiness
- Headache
- Dizziness
- Nausea
They are more likely at higher doses. For signs of taking too much and what to do, read how much melatonin is too much. Two more things are worth knowing. Labels are not always right: one lab test found some products held far less melatonin than the label said, and some held far more.7 In a 2023 test of 25 melatonin gummies, 22 did not match their labels.8 And gummies that look like candy are a real risk for kids. Calls to US poison centers about children taking melatonin rose 530% from 2012 to 2021.9 Keep melatonin out of reach.
Check with your doctor first if
- You are pregnant or breastfeeding.
- You take blood thinners, diabetes medicine, blood pressure medicine, birth control, or medicine that calms the immune system.
- You take other sleep medicine or medicine that makes you drowsy.
- You have heart disease, seizures, or depression.
- You snore loudly or stop breathing in your sleep. Sleep apnea needs its own care.
- Your sleep trouble has lasted more than a few weeks.
Worried about memory? Read can melatonin cause dementia. On blood pressure medicine? Read melatonin and blood pressure.
How I tell friends to use melatonin
There is no one answer that fits everyone. What helps most people is a few things done together:
- Know why you are taking it. Melatonin helps tell your body that night has started. It is not meant to knock you out.
- Start low. Stay in the 0.3 mg to 3 mg range sleep doctors point to, not 5 mg or 10 mg.5
- Take it at the same time each night, about 30 minutes before bed.5
- Pair it with good habits. Go to bed and wake up at the same time, dim the lights in the evening, and keep your phone out of bed. These are part of CBT for insomnia.10
- Check in after a few weeks. If it is not helping, stop. If you want to keep going, talk to your doctor about a plan.
For more on dose, read my guide to how much melatonin you should take.
Where Driffly fits
A low dose, by design
Melatonin levels fall as we get older.13 That is why I chose a low dose for Driffly: 1 mg, the same amount behind the European Union's approved melatonin sleep claim.12 It is meant to support your body's own night signal, not flood it.*
- 1 mg of melatonin in each strip.
- Valerian root, lavender, chamomile, and hibiscus to support a calm wind down.*
- Melts on your tongue. No water and no sugar.
Every order comes with a 30 night money back guarantee.
Common questions about melatonin safety
Is melatonin bad for you?
For most adults, no, when used at a low dose for a short time. The most common side effects are mild.2,6 Data on many years of use is limited, so use the lowest dose that works.
Is it safe to take melatonin every night?
Many adults take it nightly for weeks or months. Studies of up to 6 to 12 months did not find withdrawal when people stopped.3,4 If you plan to use it longer, talk to your doctor.
Is melatonin bad for your heart?
A 2025 study linked long term melatonin records to more heart failure, but it could not prove melatonin was the cause.1 If you have heart disease, ask your doctor before using it. Read my full breakdown of the heart study.
Can you get addicted to melatonin?
Melatonin is not known to be habit forming the way some sleeping pills are. In long term studies, people did not have withdrawal when they stopped.3,4
What happens if you stop taking melatonin?
Most people simply go back to how they slept before. If your sleep was poor before melatonin, that problem may return, which is why good sleep habits matter too.10
Is melatonin safe for older adults?
Many studies of melatonin were done in adults over 50 or 55.3,5 Older adults often take more medicines, so check with a doctor or pharmacist for interactions first.
Sources
- American Heart Association. Long-term use of melatonin supplements to support sleep may have negative health effects. News release on a study by Nnadi E, et al., presented at Scientific Sessions 2025. November 2025.
- National Center for Complementary and Integrative Health. Melatonin: What You Need To Know.
- Lemoine P, Nir T, Laudon M, Zisapel N. Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effects. Journal of Sleep Research. 2007;16(4):372-380.
- Lemoine P, Garfinkel D, Laudon M, Nir T, Zisapel N. Prolonged-release melatonin for insomnia: an open-label long-term study of efficacy, safety, and withdrawal. Therapeutics and Clinical Risk Management. 2011;7:301-311.
- Zhdanova IV, Wurtman RJ, Regan MM, et al. Melatonin treatment for age-related insomnia. The Journal of Clinical Endocrinology and Metabolism. 2001;86(10):4727-4730.
- Mayo Clinic. Melatonin side effects: What are the risks? Expert Answers, Adult Health.
- Erland LA, Saxena PK. Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content. Journal of Clinical Sleep Medicine. 2017;13(2):275-281.
- Cohen PA, Avula B, Wang YH, Katragunta K, Khan I. Quantity of melatonin and CBD in melatonin gummies sold in the US. JAMA. 2023.
- Lelak KA, Vohra V, Neuman MI, Toce MS, Sethuraman U. Pediatric melatonin ingestions, United States, 2012 to 2021. Morbidity and Mortality Weekly Report. 2022;71(22):725-729.
- Qaseem A, Kansagara D, Forciea MA, Cooke M, Denberg TD. Management of chronic insomnia disorder in adults: a clinical practice guideline from the American College of Physicians. Annals of Internal Medicine. 2016;165(2):125-133.
- Sateia MJ, Buysse DJ, Krystal AD, Neubauer DN, Heald JL. Clinical practice guideline for the pharmacologic treatment of chronic insomnia in adults. Journal of Clinical Sleep Medicine. 2017;13(2):307-349.
- European Commission. Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods (melatonin: reduction of time taken to fall asleep, at least 1 mg per portion). 2012.
- Karasek M. Melatonin, human aging, and age-related diseases. Experimental Gerontology. 2004.
Tyler Smith, RN, BSN, BA is a registered nurse and the founder of Driffly. He writes and reviews the articles in the sleep education hub. About Tyler
The author is the founder of Driffly, which sells the product mentioned in this article. This article is for education and is not medical advice. *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.