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Many of us think of melatonin only as an over-the-counter sleep aid, given its widespread use. But melatonin is a hormone already circulating through our bodies, like adrenaline or cortisol.
As a sleep psychologist, when I first mention melatonin to patients, they often interrupt to say, "I tried that. It didn’t work.” They are confusing our bodies’ naturally synthesized, "endogenous” melatonin with pill, gummy, liquid or other "exogenous” forms of melatonin.
Both endogenous and exogenous melatonin can help us sleep better if we understand how to sidestep pitfalls and make them work for us.
How light affects melatonin output, rhythm
Melatonin, among other functions, tells our bodies when it is time to sleep. And this function is cued by the timing of light and darkness. Darkness promotes melatonin, and light suppresses it. The blue end of the spectrum (present even in white light) is melatonin’s most potent - but not exclusive - suppressant.
But over the millennia, we have introduced inconsistency to the timing of light and darkness, and therefore to our melatonin and sleep rhythms.
Humans evolved near the equator. Day and night were of roughly equal length, and there was scant seasonal variation in patterns of light and dark. As we migrated to other latitudes, and as we modernized, we introduced seasonal variation, artificial light, cross-time-zone travel, daylight saving time and close-range screens.
Luckily, our bodies evolved to adjust to new "time zones” - patterns of light and darkness. This adaptability is both our strength and our Achilles’ heel because we want to be able to adapt if we move from D.C. to California, but we don’t want our biological rhythms upended by light needed to read a short story to get back to sleep in the middle of the night.
Melatonin plays an important part in this adaptability. And by regularizing its activity, we encourage robust output and maintain our biological rhythms when we don’t want them altered.
Under optimal conditions, we begin to ramp up melatonin production two to three hours before sleep (in primitive concert with sunset). Levels are high all night long until morning light quashes it and inclines our bodies to begin secreting it again in the evening.
When this ancestral cycle is disrupted by inconsistent, melatonin-suppressing, artificial nighttime light and weak indoor morning light, our rhythms are forced to recalibrate to new time zones, often haphazardly. (And the chaos itself tends to diminish nighttime melatonin output.)
Fortunately, ample light in the morning, throughout the day and in the early evening mitigates the undesirable melatonin-suppressing effects of late-evening light.
How to stabilize and promote ample melatonin
There are ways to use natural and artificial light to support our bodies’ production of melatonin to help us sleep better.
Go outside (ideally) for daily light for 15 minutes (without looking at the sun) 16 hours before preferred sleep. For instance, begin at 7 a.m. if you desire regular 11 p.m. sleep. Some gentle indoor light for 30 or so minutes before that is fine, much as light gradually accretes with sunrise.
Work near a window, if possible, during the day. Mildly blue-enriched indoor light would be a second choice.
Spend some time outdoors in the early evening. In the winter, you can enhance indoor light then.
Dim all light and eliminate the blue end of the spectrum two hours before sleep (at 9 p.m. for an 11 p.m. sleep time) until lights out. Blue-blocking can best be achieved with special glasses, screen filters and red bulbs rather than apps. Limit close-range screens.
Blue-block and dim any middle-of-the-night light. Light continues to exert an effect even after it is turned off, and brief exposures can add up.
These steps are not a substitute for individualized health care; nor are they for those who want to significantly alter their sleep timing.
Melatonin as a supplement
As a supplement, melatonin can serve as a sleep aid in older age, when we naturally produce less. It can assist in treatment of disorders of biological rhythms. It is sometimes recommended for migraines, irritable bowel syndrome and other conditions. It can also have positive effects on inflammation and immunity.
But consult a physician about use, dosing, timing, controlled-release vs. immediate-release formulations, safe brands, and melatonin vs. a prescription agonist - which binds to a common receptor and produces a similar effect - such as ramelteon.
What to consider when using a melatonin supplement
Some people inadvertently misuse melatonin: As a hypnotic. While there are exceptions, melatonin is not that efficacious for sleep onset and maintenance. It works better as a "chronobiotic” to manipulate biological rhythm for conditions such as jet lag, delayed sleep phase (night-owlishness) and impaired sleep timing in people who are blind.
At concerningly high doses. We produce melatonin in minute quantities in response to exquisitely orchestrated instructions from the hypothalamus. Doctors often recommend between 0.3 and 5 mg.
Doses greater than or equal to 10 mg are not often associated with serious adverse events, but may have unintended consequences and exacerbate side effects such as headaches, dizziness, daytime sleepiness and nightmares. High doses may also desensitize the brain to its effects.
At the wrong time. Phase response curves help guide what time to take melatonin to shift or maintain the timing of sleep. Two to three hours before sleep mimics sunset. Melatonin won’t help sleep much when your natural levels are already high, but it might throw off your rhythm if it’s (still) in your system at the wrong time (more likely at high doses).
For too long. We don’t know enough about long-term - greater than six months - safety.
From the wrong source. Studies have exposed inconsistent and sometimes vastly higher doses than labels indicate. Purity is another concern. Look for the USP or NSF mark for pharmaceutical-grade melatonin.
Without a doctor’s input. Melatonin should not be used by people with certain conditions (for instance, autoimmune diseases) or on certain medications (such as anticoagulants, seizure medications and immunosuppressants). Risks in older adults must be weighed.
Coaxing your own melatonin to work for you and using supplements thoughtfully can be of great benefit to sleep. But don’t hesitate to seek insomnia treatment if you need further help.
