Melatonin, Circadian Rhythm, and Supplementation
Sleep troubles are common in modern life, with about 70% of Americans reporting that they get insufficient sleep at least once a month. Getting better sleep is about consistency, good sleep hygiene, and overall hormonal and gut health. Melatonin is a naturally occurring hormone produced by the pineal gland that helps regulate your circadian rhythm, but it’s also a supplement that can help get you back on track.
A melatonin supplement might be a go-to over-the-counter natural sleep aid for when you’re tossing and turning, but how long does melatonin last in your system? Will it result in a groggy morning or daytime sleepiness? And how far ahead of bedtime should you take it?
Here, I’m going to answer all of these questions, provide a better understanding of how your body makes and uses melatonin, and explain why supplementing for short-term insomnia is a viable solution for most.
How Long Does Melatonin Last In Your System?
On average, melatonin stays in your system for four to eight hours. The speed at which melatonin hits your bloodstream and starts helping you get a good night’s sleep depends a lot on how you take it. Sublingual tabs, liquids, and intranasal sprays will hit your bloodstream more quickly than an in-tact pill that you swallow, for example. But because supplements aren’t regulated by the Food and Drug Administration (FDA) before hitting the market, onset ranges widely .
And extended-release melatonin will absorb more slowly (hence the name) than the immediate-release forms. That being said, for an immediate-release melatonin supplement, you’re likely to begin feeling the effects within about an hour .
Melatonin taken in typical dosing (1-5 mg) has a half-life of about 20 minutes when taken orally (and not in extended-release form). That means it takes about 20 minutes for your body to process and eliminate half of your dose of melatonin.
So, in an ideal world, you’d take your melatonin 30 minutes to an hour before bed so that you have some time to wind down, get in bed, and close your eyes. From there, the effects of melatonin slowly decline, and it’s completely out of your system within 4 to 8 hours . Because of the rapid onset and short half-life, immediate release melatonin is ideal for people who have trouble falling asleep but not staying asleep.
Extended-release (also called prolonged release or slow release) melatonin supplements are a little bit different. As the name suggests, these melatonin pills are designed to release your total dose of melatonin over a longer period of time throughout the evening.
With extended-release melatonin, you can expect peak melatonin levels about 3-4 hours after you’ve taken your pill with food . However, the half-life remains less than 30 minutes. One older study from 1999 showed inconsistent results, with one extended release capsule reaching its peak in four hours and the other reaching its peak at 12 hours . This type of melatonin is also more effective at helping you fall asleep than stay asleep, even though it lasts a bit longer in your system.
When it comes to whether or not the effects of melatonin carry over into the morning, it’s fairly individual. Some people do report next-day drowsiness as a side effect, while others may wake feeling refreshed.
For both types of melatonin, you ideally want to take it while allotting at least eight hours of time for sleep. That way, you’ll minimize your chances of waking up with drowsiness.
Your Body Should Make Melatonin Every Night
Endogenous melatonin production requires adequate serotonin levels and is produced in the pineal gland. Your pineal gland produces and releases melatonin in response to darkness at night to help you wind down for sleep, which is why it’s so important to begin dimming lights and reducing light exposure (especially blue light-emitting devices like phones, TVs, and tablets) as you wind down for bed .
Melatonin helps regulate your body’s circadian rhythm (the 24-hour sleep-wake cycle). If disrupted, this can result in other health disruptions, including those related to gut health [5, 6, 7, 8]. In other words, there seems to be a feedback loop between sleep problems and gut problems, and sleep improvements and gut improvements.
If your body is producing an inadequate amount of melatonin, you’re more likely to develop a sleep disorder and may need to supplement to get back on track. Circadian rhythm disorders and other types of insomnia can make it harder to fall asleep and cycle through the various stages of sleep, and some studies show that supplementing melatonin may help.
However, studies on certain populations have shown either mixed results or no improvement in sleep with up to 5 mg of melatonin supplementation. These studies looked at participants with additional physical or mental health conditions, such as Alzheimer’s and dementia patients, menopausal women, and post-surgical patients [11, 12, 13]. It might still be worth giving melatonin a try if you fall into these categories, as it might still work for you, especially since melatonin is generally safe and low cost with few (if any) side effects.
Maximizing Your Melatonin Production With Good Sleep Hygiene
To maximize your own body’s melatonin production, sleep hygiene should be priority number one. This means you’ll need to focus on:
- Establishing a consistent bedtime and wake time every day (even on weekends!) and avoiding shift work, if possible [14, 15, 16]
- Avoiding big or heavy meals close to bedtime
- Minimizing caffeine and alcohol consumption, especially in the latter part of the day 
- Avoiding highly stimulating or stressful entertainment right before bed
- Minimizing blue light or bright light exposure from screens after the sun goes down, but especially within a couple of hours of bedtime 
- Getting regular exercise that brings your heart rate up every day, but not within a few hours of bed time
- Establishing an evening routine that will signal to your brain that it’s time to start winding down (dim the lights, brush your teeth, walk away from your phone, do some gentle stretching or muscle relaxation, read something relaxing or even boring, etc.)
- Seeking treatment for breathing problems, snoring, or sleep apnea, which can all disrupt sleep and reduce sleep quality
- Getting your gut health in order with probiotics and anti-inflammatory foods [19, 20, 21]
This may seem like a lot, but work on these recommendations one at a time so that you don’t feel overwhelmed. If you need help setting goals to tackle your sleep challenges, reach out to set up an appointment with us.
How Supplemental Melatonin Works
The idea behind melatonin supplementation is to mimic the effects of melatonin to help you sleep.
For any number of reasons, your body may begin to lag in its production of natural melatonin, causing sleep disturbances or problems falling asleep. In this case, you might consider a dietary supplement. The American Academy of Family Physicians considers melatonin a first-line treatment for insomnia due to its low occurrence of side effects and demonstrated efficacy for the relief of insomnia .
Supplemental melatonin has been shown to be effective in the treatment of primary insomnia, age-related insomnia, jet lag, shift work-related sleep disorders, post-traumatic brain injuries, and some neurodegenerative disorders. As I mentioned above, it doesn’t seem to help with dementia or Alzheimer’s patients [11, 12, 13, 22].
You’ll want to take the lowest dose that’s effective for you, starting with 0.5 mg, and not exceeding 10 mg. Studies seem to indicate that dosing over 5 mg doesn’t add any benefits. We’ve found in our clinic that when our patients take 10 mg or a higher dose, they often experience worse insomnia than when they don’t take melatonin at all . So be conservative by starting with a low dose, and add 0.5 mg at a time to find out how melatonin affects you.
Safety Concerns and Potential Side Effects
Always seek medical advice before starting a new supplement, especially if you’re taking prescription drugs or have other underlying illnesses. Melatonin can stimulate your immune response, which is why you need to know when not to use it. Specifically, avoid melatonin if you’re already taking benzodiazepines, alcohol, or zolpidem, if you have an autoimmune disorder like rheumatoid arthritis or asthma, or if you’ve had an organ transplant and are taking immunosuppressants [22, 24].
Melatonin also shouldn’t be mixed with other depressants. It’s also not been tested for safety on pregnant or breastfeeding mothers.
For those who don’t have these health concerns or aren’t taking these pharmaceuticals, potential side effects of melatonin are few, mild, and pretty rare. The most common are drowsiness, daytime sleepiness, headaches, and nausea.
A 2018 umbrella review of the available research found low-quality evidence of other mild side effects, including dry mouth, dyspepsia, diarrhea, rash, upper respiratory infection, and hypothermia . More work needs to be done to identify the effects of long-term use of melatonin, but short-term and long-term side-effects may be the same.
There’s little reason to believe melatonin is addictive, which gives it a leg up against pharmaceutical sleep aids. In fact, melatonin has been successfully used in clinical trials to help adults addicted to hypnotics or benzodiazepines eliminate their dependency on those drugs for sleep .
The Bottom Line
Melatonin stays in your system for only a short time. The half-life is about 20 minutes, and it’s much more effective for helping you fall asleep than stay asleep. Extended-release melatonin, although it lasts in your system for longer, is also better for falling asleep than staying asleep. To answer the question “How long does melatonin last?” is difficult, but most research points to a 4-8 hour window.
Good sleep hygiene is an important component of improving your overall sleep, no matter what types of supplements or pharmaceuticals you choose to use. It’s important to establish good nighttime routines, get your gut health in order, avoid evening caffeine, alcohol, and heavy meals, and get regular exercise in order to get your sleep schedule back on track. For help with any and all of these lifestyle changes, reach out to the clinic to get started.