I keep hearing from people who are trying to fix their sleep problems by taking melatonin. This is because most people know melatonin as the #1 sleep hormone (and it is successfully marketed as such). Yet, many don’t know exactly what function it has in relation to sleep.
True, melatonin is a hormone that is immensely important in regulating our internal clock and thus our sleep, but can be taking melatonin really improve falling asleep or even sleeping through the night? That’s the question I want to address in this article.
The interplay between your biological clock and melatonin
Since melatonin is closely linked to your biological clock, also known as the circadian rhythm, let’s look first at what that is.
Your biological clock determines when you want to be awake and when you want to be asleep. During the day, the circadian rhythm activates many brain and body mechanisms designed to keep you awake. These processes are then shut down during the night.
So the clock’s wake-up drive becomes stronger during daylight hours but weaker during the night. Thus, wakefulness and sleep are under the control of the circadian rhythm. Whether you have slept or not, your circadian rhythm will regulate every twenty-four hours to give your body and brain optimum time to rejuvenate.
How fits the sleep hormone melatonin in here?
Melatonin acts as a messenger between your biological clock, your brain, and your body. In other words, your biological clock transmits its repeating day and night signal to your brain and body through the use of melatonin.
Melatonin is made by your pineal gland, but it’s your biological clock that controls its production. And the main factor influencing its production is daylight – or lack thereof. The less sunlight there is, the more melatonin is produced. That’s why melatonin is also called the “vampire hormone.”
How works the production process of melatonin?
Through your optic nerves, your internal clock receives information about the intensity of incoming light. When it gets dark at night, your internal clock communicates to your brain to release more melatonin, with the result that you become sleepy.
When you’re sleeping, the melatonin levels slowly decrease during the night. As the daylight from the morning enters through your optical nerves, your pineal gland stops the production of melatonin, and your cortisol hormone levels are now high.
This is the signal to your brain and body to change state to conscious and active wakefulness. Then, at night, when it gets dark, your melatonin levels rise again, calling for another sleep event.
The influencing factor of light on your melatonin levels
So changing the light-dark cycles can strongly influence your biological clock and your circadian rhythms and alter sleep-wake processes. Some of those influencing factors are work shift, jet lag, and exposure to light from computer screens and mobile devices during the night.
For this reason, many sleep experts recommend avoiding screen time before bed. The excess light can trick your body into thinking it’s daytime, which messes with your circadian rhythm and prevents the release of sleep hormones. This can keep you up or prevent you from falling into a deep, restorative sleep.
Melatonin has little influence on the generation of sleep
Melatonin helps regulate the timing of when sleep occurs by systematically signaling darkness throughout the organism. But melatonin has little influence on the generation of sleep itself. Or as Mathew Walker explains it skilfully in his excellent book Why We Sleep: “… think of sleep as the Olympic 100-meter-race. Melatonin is the voice of the timing official that says, ‘Runners, on your mark,’ and then fires the starting pistol that triggers the race. That timing official (melatonin) governs when the race (sleep) begins, but does not participate in the race.”
This last sentence states that melatonin is crucial for signaling bedtime but does nothing to generate sleep, a mistaken assumption that many people hold and the answer to whether melatonin is an effective sleep aid.
Yes, it can help jump-start the sleep event. Still, since it is not involved in the generation and maintenance of sleep, it is not a powerful sleep aid to cure insomnia (aside from a potential placebo effect that should not be underestimated!).
So no real benefit at all from taking melatonin?
Not so fast – since melatonin helps initiate the sleep process, it can be beneficial if you need to adjust to a new time zone. We all know that traveling between different time zones is a significant cause of poor sleep. As you travel, your biological clock differs from the local time of your destination.
For example, if you travel across the USA from the West Coast to the East Coast, you’ll be 3 hours behind. If you wake up with the rest of the East Coast population, it will likely feel like 4 or 5 am. Your biological clock will eventually adjust to the current time zone you are in, but it will take a few days (generally about one day per hour).
One thing you can do to better adjust to a new schedule is to get natural light on your skin in the morning. Remember that light resets your biological clock. A short walk outside will help your internal clock keep time and improve your sleep quality the following night.
Why melatonin can help to prevent jet lag
Another thing you can do to help with jet lag is taking a melatonin supplement. Imagine, for example, you were flying from Los Angeles to London. After arriving that day, you have real difficulty getting to sleep and staying asleep that night. In part, this was because melatonin was not being released during your nighttime in London. Your melatonin rise was still many hours away, back on California time.
But let’s imagine that you take some melatonin after arriving in London. Here is how it works: at around seven or eight pm London time, you would take a melatonin pill, triggering an artificial rise in circulating melatonin that mimics the natural melatonin spike currently occurring in most people in London. Consequently, your brain is fooled into believing it’s nighttime, and with that chemically induced trick comes the signaled timing of sleep.
It will still be a struggle to generate the event of sleep itself at this – for you – irregular time, but the timing signal significantly increases the likelihood of sleep occurring.
Since melatonin only plays a crucial role in timing your sleep but not in the actual sleep event, it is not a helpful sleep aid if you have chronic insomnia. But when traveling to a different time zone, taking melatonin at the right time can help to prevent jet lag.
However, keep in mind that in some countries like the US, melatonin is a dietary supplement and not medication, meaning that it is not commonly regulated by governing bodies such as the Food and Drug Administration (FDA). Scientific evaluations of over-the-counter brands have found melatonin concentrations range from −83% to +478% of the labeled content.
Some brands added things like valerian root, passionflower, chamomile, skullcap, hops, or even serotonin, a much more strictly controlled substance because an overdose can lead to serious side effects.
So be careful when purchasing melatonin supplements. While not always a guarantee of safety, certifications from organizations such as US Pharmacopeia (USP), ConsumerLab.com, or the NSF International Dietary Supplement Program can confirm that products have been tested for impurities or mislabeling.