Melatonin

What melatonin is

Melatonin is a hormone your brain makes in response to darkness. It helps set the timing of your circadian rhythms, the roughly 24-hour internal clock that governs when you feel sleepy and when you feel alert, and being exposed to light at night can hold its production back. The melatonin sold as a supplement is most often made synthetically. It is one of the most popular sleep supplements, and research suggests it may play other roles in the body beyond sleep that are not fully understood.

This page is general education about melatonin as a supplement. It is not a recommendation that you should or should not take it; that is a conversation to have with your clinician about your own situation.

What it is used for

It helps to be clear about what melatonin is good at, because it is not really a general sleeping pill. Its strongest use is as a timing signal. The evidence is most encouraging for jet lag and for a body clock that runs late (a delayed sleep-wake pattern), where it can nudge sleep earlier, and there is actually strong evidence that it can ease anxiety before surgery. For ongoing, everyday insomnia, though, there is not enough strong evidence to recommend it, and for shift work the research is small and inconclusive. Melatonin has also been studied in children’s sleep problems, but that is specifically a situation to handle with a clinician rather than on your own.

In a psychiatric setting, melatonin is something we might consider when the problem is genuinely one of timing, not as a stand-in for the treatment that addresses what is actually keeping you up. Whether it fits depends on your history, what else you take, and what you are hoping it will do. That is decided case by case, and it is reasonable to bring it up alongside guides like sleep and anxiety.

How it might work

Unlike many supplements, melatonin’s basic role is fairly well understood: it is the body’s own darkness signal, part of how your internal clock keeps time and decides when you should feel sleepy. Taking it as a supplement is essentially adding to that signal, which is why timing it well matters more than with most things and why it tends to help timing problems more than it helps insomnia in general. How much it helps a given person still varies, and plausible is not the same as proven for every use.

How people take it

There is no single right way to take melatonin, and the details are worth talking over with your clinician or pharmacist rather than copying a number from a label. A few general points apply:

• Timing is the whole point. Because melatonin works on your body clock, when you take it can matter as much as whether you take it; this is worth getting right for a timing problem like jet lag.
• Quality really varies. Studies have found that many over-the-counter melatonin products, gummies in particular, contain quite a bit more or less than the label says, and some have been found to contain other substances. Choosing a reputable, tested product matters more here than usual.
• More is not better, and smaller is often enough. Commonly used amounts are small, often around 1 to 3 mg taken before bed, and sometimes less. Many products sold over the counter contain much more, on the order of 5 to 10 mg, but for melatonin a higher amount does not work better; it mainly raises the chance of next-day grogginess.
• Keep it away from children. Accidental swallowing by young children has become common, so store it like a medicine, out of reach.

What to expect

This varies from person to person. Melatonin tends to help most when the problem is a timing one, and much less when it is general insomnia, so set your expectations by what you are using it for. If it helps, the effect is usually a gentle nudge rather than a knockout. Pay attention to how you actually feel, including the next morning. If you notice nothing, or you feel groggy through the day, that is useful information, and it is fine to stop and look at other options together. As always, this is case by case.

Possible side effects

Short-term use of melatonin appears to be safe for most people, and the side effects are usually mild. The lists below are possibilities, not certainties.

Possible more common side effects:

• Headache
• Dizziness
• Nausea
• Daytime sleepiness or grogginess

In children, melatonin’s side effects have usually been mild and can include drowsiness, more bedwetting or evening urination, headache, dizziness, and agitation; giving melatonin to a child is a decision to make with a clinician.

Less common, but a sign that could need urgent care:

• Signs of an allergic reaction: rash, hives, or swelling of the face, lips, tongue, or throat

For any of these, use the help options at the bottom of this page: call 911 or go to the nearest emergency department for a medical emergency or severe reaction, or call or text 988 for a mental health crisis.

Interactions and safety

This is the part most worth reading. Melatonin is low-risk for short-term use in many people, but several things matter:

• Some conditions need medical supervision. If you have a seizure disorder (epilepsy) or take a blood thinner, melatonin should be used only under a clinician’s supervision.
• Product quality is a real issue. Because many products do not contain what their labels claim, and some have been found to contain other substances, the brand and quality of what you buy matter.
• Older adults should be cautious. Melatonin can stay active longer in older people and cause daytime drowsiness, and a major sleep guideline recommends against using it in people with dementia.
• Children and development. Because melatonin is a hormone, there are open questions about whether it could affect a child’s development, which is another reason it is a clinician conversation.
• Keep it away from children physically. Accidental swallowing by young children has risen sharply, so store it out of reach like any medicine.
• Little is known about using melatonin during pregnancy or while breastfeeding, so that is a conversation to have first.

The simplest safeguard is to tell your clinician and pharmacist everything you take, including supplements and over-the-counter products. Knowing the full picture lets us catch a problem before it happens and decide together whether melatonin fits your plan.

When to contact your clinician

For routine questions, mild side effects, or whether melatonin fits with the rest of your plan, send a message through the patient portal or bring it to your next visit. These are part of your ongoing care and are answered in the normal course of a few business days, so they are best for things that are not urgent.

If a child swallows melatonin, treat it as urgent even if they seem fine: call Poison Control at 1-800-222-1222 for guidance, and call 911 or go to the nearest emergency department if the child is very drowsy, having trouble breathing, or hard to wake. For an adult medical emergency or severe reaction, call 911 or go to the nearest emergency department, and use 988 any time for a mental health crisis or thoughts of self-harm.

Questions to ask your clinician

• Is my sleep problem the kind of timing issue melatonin actually helps, or something else?
• If I try it, when and how should I take it?
• Does it interact with any of my medicines, especially a blood thinner or a seizure medicine?
• Is there a reason, like my age or pregnancy, that it would not be a good fit?
• How would I choose a trustworthy product?