Long-Term Melatonin Use: What a New Heart Study Means for Your Sleep Routine
A large new study has linked long-term melatonin use with a higher risk of heart failure. That sounds alarming, especially if a small tablet has become part of your nightly routine.
The calm version is this: the study does not prove melatonin causes heart problems. It does raise a sensible question, though. If you have been taking melatonin most nights for months or years, is it time to review why?
Melatonin often gets treated as the “gentle” sleep option because it is linked to a hormone the body already makes. But “natural” does not always mean risk-free, and “available without much fuss” does not mean it is right for long-term use.
This is a good moment to check the habit, not panic.
What the new study found
The research was presented at the American Heart Association’s Scientific Sessions. It was a large preliminary observational study that used de-identified health records for 130,828 adults with insomnia.
Researchers compared people with documented long-term melatonin use, meaning 12 months or more, with matched non-users. Over five years, people in the long-term melatonin group had about a 90% higher risk of developing heart failure.
The actual heart failure rates were:
Group | Heart failure over five years |
Documented long-term melatonin users | 4.6% |
Matched non-users | 2.7% |
The study also found higher rates of hospitalisation for heart failure and death from any cause among those with documented long-term melatonin use.
That is the headline. The next part matters just as much.
This study shows an association. It does not prove that melatonin caused heart failure.
Observational studies can spot patterns, but they cannot fully explain why those patterns exist. In this case, the people taking melatonin long term may have differed from non-users in ways that were not fully captured in the records.
For example, some may have had more severe insomnia. Poor sleep itself is linked with poorer heart and metabolic health. Some may have had other conditions, taken other medicines, or used over-the-counter melatonin that never appeared in their medical records.
The researchers worked with a large dataset, which gives the findings weight. Still, the study was preliminary, and its design means it should be treated as a signal for more research, not a final answer.
Why the finding still matters
A study does not need to prove cause and effect to be useful. Sometimes it gives people a reason to pause and ask better questions.
Melatonin is often used for short-term sleep timing issues, such as jet lag or a disrupted body clock. It is not the same as a general sleeping pill, and it does not work like a sedative for everyone.
An independent sleep expert commenting on the findings noted that, in the United States, melatonin is not indicated for treating chronic insomnia and should not be taken long term without a clear reason.
That point is useful well beyond the US. If a supplement has become a nightly default, it can be easy to stop asking whether it still has a clear purpose.
Long-term use can creep in quietly:
A stressful month affects sleep.
A supplement seems to help.
The stressful month passes, but the tablet stays.
Months later, it feels impossible to sleep without it.
That pattern is common with many sleep aids, including so-called natural ones. The issue is not that every person taking melatonin is doing something dangerous. The issue is that sleep problems deserve a plan, not indefinite self-management.
Natural does not mean risk-free
Melatonin is a hormone involved in the sleep-wake cycle. The brain releases it in response to darkness, helping signal that night has arrived.
Taking melatonin as a supplement can be useful for some people, especially when the main problem is sleep timing. For example, it may help shift a body clock that has been pushed later by travel, shift work, or irregular routines.
But it is still a substance that affects the body. Side effects can include morning grogginess, vivid dreams, headache, dizziness, or changes in mood for some people. It may also interact with medicines or be unsuitable for some health conditions.
There is another consideration around product quality. In some markets, including the United States, melatonin is sold as a dietary supplement and is not regulated in the same way as prescription medicines. Product quality and dose can vary from bottle to bottle, and some products may contain more or less melatonin than the label suggests.
New Zealand’s rules changed recently. Since mid-2025, approved melatonin products can be bought at a pharmacy without a prescription for short-term use, roughly up to 10 days for jet lag or up to 30 days for insomnia and pharmacists can supply larger packs (up to 13 weeks) to adults aged 55 and over. It is also still available on prescription. What has not changed: importing unapproved melatonin from overseas still needs a prescription, and Medsafe warns those products can be poor quality or variable in strength. In other words, melatonin is easier to get here than it used to be, which makes it more important, not less, to be deliberate about long-term use rather than reaching for it by default.
The broader lesson applies to the whole sleep, mental wellbeing and supplements space. If something affects sleep, mood, alertness, hormones, or medication response, it is worth treating it with care.
Sleep hygiene should come before a nightly tablet
Sleep hygiene can sound too simple, especially to someone who has been awake at 2am staring at the ceiling. But the basics matter because they train the body to recognise when it is time to be alert and when it is time to power down.
They also reduce the chance that a supplement becomes the only tool in the kit.
Keep a consistent sleep window
A regular wake time is one of the strongest cues for the body clock. Going to bed at exactly the same time every night is not always realistic, but waking at roughly the same time most days can help stabilise sleep.
Try to avoid sleeping in for hours on weekends to “catch up”. It can feel good short term, but it may push the body clock later and make Sunday night harder.
Get bright light early in the day
Morning light tells the brain that daytime has started. That helps set up melatonin release later in the evening.
Outdoor light works best, even on cloudy days. A short walk, breakfast near natural light, or a few minutes outside can help. This is one reason morning exercise can support better sleep. A local routine, whether that means walking the dog, training before work, or heading to a place like Keep Fit Matakana Gym, can do more for sleep than people expect.
Dim the evening environment
Bright light at night, especially close to the face, can delay the body’s natural sleep signals. Screens are not the only issue. Bathroom lights, kitchen lights, and late-night scrolling all tell the brain to stay awake.
A simple evening shift can help:
Lower household lighting in the last hour.
Use night mode on devices if screens are unavoidable.
Keep the bedroom dark, cool, and quiet.
Charge the phone away from the bed if it fuels checking.
Build a repeatable wind-down routine
The brain likes patterns. A short routine done in the same order can become a signal that sleep is coming.
It does not need to be elaborate. Ten to 30 minutes is enough for many people. A useful wind-down might include:
A warm shower.
Light stretching.
Reading a physical book.
Calm music or a breathing exercise.
Writing down tomorrow’s key tasks to stop mental looping.
The goal is not to force sleep. It is to create conditions where sleep is more likely.
When melatonin may be worth discussing
Melatonin is not automatically bad. For some people, it may be appropriate, especially for short-term timing problems or under medical advice.
The key is to avoid treating it as a casual nightly habit for chronic insomnia without review.
A conversation with a GP, pharmacist, sleep physician, or qualified health professional is especially sensible if:
You have taken melatonin most nights for more than a few weeks.
You feel unable to sleep without it.
You need increasing doses to get the same effect.
You have heart disease, high blood pressure, diabetes, kidney disease, or liver disease.
You take medicines for mood, blood pressure, blood thinning, seizures, or immune conditions.
You feel sleepy during the day or unsafe driving.
You snore heavily, gasp during sleep, or wake with morning headaches.
Your insomnia started after anxiety, depression, pain, grief, menopause symptoms, or major stress.
Sleep issues often have treatable causes. These can include sleep apnoea, restless legs, pain, reflux, alcohol use, medication effects, anxiety, low mood, or an irregular work schedule.
Melatonin may not be the right tool if the root problem is not body-clock timing.
What to do if you take melatonin every night
Do not suddenly stop or change a long-term sleep aid based only on a news headline. That can backfire, especially if sleep is already fragile.
A better next step is to review the habit in a structured way.
Check the basics first
Write down the details:
The dose you take.
The time you take it.
How many nights per week you use it.
How long you have used it.
Why you started.
Whether it still helps.
Any morning grogginess, mood changes, vivid dreams, or headaches.
Bring that information to a health professional. It is much easier to give good advice when the pattern is clear.
Ask better questions
Useful questions include:
Is melatonin the right choice for my sleep problem?
Is my dose appropriate?
Should I be using it short term only?
Could it interact with my medicines or health conditions?
Should I be assessed for sleep apnoea or another sleep disorder?
What is a safe plan if I want to reduce or stop?
For chronic insomnia, many guidelines favour behavioural treatment, such as cognitive behavioural therapy for insomnia, often called CBT-I. It focuses on sleep patterns, thoughts about sleep, stimulus control, and habits that keep insomnia going.
It can take effort, but it targets the problem more directly than simply adding a nightly tablet.
The heart study should change the conversation, not create panic
The new research does not mean everyone who has taken melatonin should worry they have harmed their heart. It also does not mean melatonin has no place.
It does mean long-term, routine use deserves more caution than it often gets.
The most balanced reading is this:
What the study suggests | What it does not prove |
Long-term documented melatonin use was linked with higher heart-failure risk in adults with insomnia. | Melatonin directly caused heart failure. |
People using it for 12 months or more may need closer review. | Short-term or medically guided use is unsafe for everyone. |
More research is needed. | The finding should be ignored. |
That middle ground matters. Fear can make people stop useful treatments too quickly. Complacency can keep people stuck in habits that should have been reviewed years ago.
A calmer way to think about sleep support
Good sleep rarely comes from one thing. It usually comes from a stack of small, repeated signals: morning light, daytime movement, steady routines, less late caffeine, lower evening light, and a bedroom that supports rest.
Supplements can sometimes play a role, but they should not be the whole plan. If melatonin has become a nightly fixture, treat this new study as a prompt to review it.
Start with the low-risk foundations. Keep a regular wake time. Get outside early. Make evenings darker and quieter. Build a wind-down routine. Then speak with a qualified professional if sleep still feels out of reach or if you have been using melatonin long term.
This article is general information only and is not personal medical advice. For long-term insomnia, heart concerns, or questions about supplements and medicines, talk with a health professional who knows your history.
The takeaway is simple: do not panic about melatonin, but do not put it on autopilot either. Your sleep routine should support your health, not quietly become a habit no one has checked for years. _________________________________________________________________________ Justin, Keep Fit Matakana 📍 Matakana Village, Auckland | keepfitmatakana.co.nz Follow us on Instagram @keepfitmatakana for more tips from the team.
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