How does melatonin work?
When it comes to the science of sleep, you won’t get far without coming across melatonin. Often referred to as the ‘sleep hormone’, melatonin plays an important role in healthy sleep and regulating your circadian rhythm.
Melatonin is a naturally occurring hormone but can also be purchased as an over-the-counter (OTC) supplement. According to a ConsumerLab report, 29.5% of people who use daily supplements take melatonin, making it one of the most commonly used supplements.
A supplement to help you sleep might sound like a great solution, but it’s far from perfect. Knowing how this supplement works and its pros and cons is the first step in determining whether it’s a good fit for your lifestyle.
What is melatonin?
Melatonin is a naturally occurring (endogenous) hormone produced by the pineal gland in the brain and secreted into the bloodstream. Its production is rhythmic and determined by our sleep-wake and light-dark cycles. It helps in transitioning our brain and body to sleep.
Man-made (exogenous) melatonin supplements have increased in popularity, with just about any form available including capsules, liquids, patches and even chewable gummies. Most melatonin supplements are made synthetically in a lab and are available in fast- and slow-acting varieties.
The chemistry behind how melatonin works
There are two factors that regulate melatonin in your body - your natural circadian rhythm and environmental light. Your body’s melatonin starts to increase in the evening and peaks at around 2 am. Daytime concentrations of melatonin are barely detectable.
Did you know?
Melatonin production in babies isn’t regulated until they reach around 3 months. There’s a lot more going on here than just a lack of melatonin or an established circadian rhythm, but gives some good insight to those sleepless nights you might experience with a newborn!
Daylight, and even bright indoor lights, inhibit the production of melatonin. Your eye’s retina detects light and sends a signal to part of your brain, the suprachiasmatic nucleus. This is then sent to other parts of the brain, down your spinal cord, and finally back to your brain’s pineal gland where melatonin is predominantly produced. These signals tell your pineal gland to stop producing melatonin during daytime hours.
In the absence of sunlight (or bright artificial lighting and devices), these signals are not activated, so your pineal gland can freely produce melatonin. Complex biochemical reactions work in the background to create the hormone, from its starting ingredient, tryptophan. Tryptophan is transferred to the pineal gland from the bloodstream.
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The amount of melatonin your pineal gland produces is largely determined by how active one of the enzymes is: serotonin-N-acetyltransferase, otherwise known as SNAT. Coincidentally, SNAT is only active at night and is degraded, or inactive, during the day. SNAT is critical for the conversion of tryptophan to melatonin, so when it is activated at night, melatonin can be produced and we start to feel sleepy.
How do melatonin supplements play into this?
Taking melatonin supplements claim to add or supplement your body’s natural supply, theoretically helping to improve the quality of your sleep. However, there are some limitations to these claims.
Most melatonin supplements are taken orally. While tablets, gummies and liquids are an easy way to get the supplement into your body, it’s not especially good at getting the hormone into your bloodstream, where it’s needed to work most effectively.
This means the bioavailability of oral melatonin supplements is quite poor. Some studies have reported a bioavailability as low as 15%, meaning that the other 85% is passed through your body without ever reaching your bloodstream.
That said, studies have shown that melatonin supplements can be useful in some cases.
Who might benefit from melatonin supplements?
While the research isn’t conclusive on melatonin, there is some supporting evidence that it can be beneficial in some cases. We’ve broken down some of the most common reasons people reach for melatonin and whether the science is there to back it up.
Does melatonin work for shift workers?
Changing your sleep times due to shift work can be a frustrating and exhausting experience. While melatonin might look like it could help make shift work easier, there’s little to no evidence to back it up.
Studies on shift workers using melatonin have had small sample sizes and inconclusive results, though there are some anecdotal reports to support it.
Can melatonin help with jet lag?
Frequent travelers are no stranger to jet lag. While usually only a short term problem, melatonin has been found to reduce its effect on people traveling over five or more time zones. Research about the use of melatonin for jet lag sufferers has been generally positive.
Is melatonin good for insomnia?
Some studies have shown that melatonin can be effective in treating short-term insomnia in adults who are otherwise healthy.
There isn’t conclusive evidence that melatonin is effective in treating long-term, chronic insomnia, so doctors recommend against using this as a treatment.
Is melatonin safe?
Short-term use of melatonin is considered safe, with few side-effects for most people. Always follow the instructions provided and consult your GP before taking any supplements.
The most common side-effects encountered when taking melatonin supplements are:
- Drowsiness during the day
- Headaches
- Dizziness
While few people experience these effects, it’s always worth consulting with your doctor if melatonin will work for you. This is especially true if you fall into any of the following cases:
- Taking medications currently
- Have had an allergic reaction to a medication in the past
- Are pregnant or breastfeeding
- Are older in age
- Have dementia
As a supplement, it’s also worth noting that it is less strictly regulated by the Food and Drug Administration (FDA). This means that what is written on the packaging isn’t necessarily 100% what you’re getting.
If this concerns you, keep an eye out for a USP verified badge on the supplement bottle. This means that the supplement has been verified by the United States Pharmacopeia to contain exactly what it says on the label.
How long does it take for melatonin to work?
Melatonin takes 30-60 minutes to start working for most people. You should allow this much time before you go to bed for the best results.
This time will vary from person to person, however, and will also depend on other factors about the supplement’s formulation.
What can I do instead of taking supplements?
Melatonin supplements aren’t for everyone. Whether they don’t work for you personally or you prefer to take a natural approach to improving your sleep quality, there are alternatives that don’t involve supplements or drugs.
Make the most of your natural melatonin by improving your sleep hygiene. This means improving your habits, routines and environmental factors that affect your ability to sleep.
With an understanding of how melatonin is produced in the body, you can take advantage of this to maximize its effectiveness. This means following your body’s natural circadian rhythm when you can, and avoiding bright light - natural and artificial - in the evenings leading up to bed time.
