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Understanding Melatonin: Are People Taking Too Much?

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Many of my patients, over the years, have taken melatonin. Many other patients have asked me about it, but I’ve never had much to say. I hadn’t heard anything particularly bad about it, but couldn’t really recommend it. “Research melatonin” has been on my “To Do” list for a long time.

So here’s what I’ve discovered: Melatonin is a hormone. I’ve known that since medical school, of course, but that fact has struck me as peculiar these past few weeks. Why? Because it’s sold over the counter, and many people take massive amounts of it. No other hormone is available like this. The use of other hormones, such as insulin and thyroid hormone, need careful monitoring. Is melatonin so universally safe that it can be taken at any dose, for however long? The more we learn about melatonin, the less that seems to be the case.

Hormones are substances produced in one place that then go into the bloodstream and have their effect somewhere else. Melatonin is produced in the pineal body, which is just outside the brain proper. Ten times as much of it is made during the night as during the day. Our bodies sense when it is dark and tell the pineal body to make melatonin. If we cross six time zones, however, it takes a few days for the pineal to catch up and produce melatonin at the proper time. Hence comes Jet Lag.

So do people with insomnia benefit from melatonin? Many of them swear by it, but I’m wondering whether they are taking too much. The pills in pharmacies are generally 3mg or 5mg. But the amount that reproduces what our bodies produce at night is equivalent to somewhere between 0.1mg and 0.5mg. Higher doses flood the brain with melatonin, and make it actually less sensitive to its effects. So here is where it is not good to follow the “If a little is good, then more is better” principle. Since a little is all that is needed, stick with a little.

Studies are showing that the ideal amount of melatonin for sleep problems seems to be 0.3mg. But how can you take “0.3mg” when the pill is 3mg? Do you crumble it up and take a tenth, somehow? Not practical. There are liquid preparations available, with one dropperful giving 1.0mg. So you could take a third of a dropperful. If you can’t find it at your pharmacy, check online at www.drugstore.com.

As we age, we gradually produce less melatonin. I wonder if this is why so many older people have trouble sleeping. In the last few weeks, since I’ve been reading about melatonin, I’ve started recommending it to my older patients with insomnia. But I urge them to use the liquid so they only take 0.3mg a night. They may end up needing a little more, but, as with all medications, I much prefer starting at a low dose and creeping up slowly. I’ll follow up in a few months with how people have responded.

*This blog post was originally published at Making Sense of Medicine*


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3 Responses to “Understanding Melatonin: Are People Taking Too Much?”

  1. Elliot Krane says:

    Interesting thought, but you ignore the bioavailability of melatonin when orally ingested, which is certainly not 100%. Therefore taking 3mg is not equivalent to 10x the physiologic amount produced, the multiplier depends entirely on the amount absorbed, the amount subjected to first pass hepatic metabolism, the amount protein bound in the blood, and finally the amount actually delivered to effector sites in the brain. I’m not sure, in fact I doubt, that any of these variables have been studied.

  2. Amy Givler says:

    This is a good point, Elliot. The first pass effect for melatonin is significant, and the blood concentrations of the same dose varies widely from person to person. And yes, the medical literature doesn’t have nearly the number of studies you would expect for a widely-available hormone. The reason for that, probably, is that it is not under patent. Still, there have been studies done, over the years, in which people are given varying doses of melatonin. The lower dose I discuss in my post, 0.3mg, is associated with a more physiologic response in the plasma, with significant benefits to sleep — both sleep latency and sleep architecture. Also, tolerance to this dose doesn’t develop, whereas it does with the 3mg dose. I pulled most of my study from the UpToDate article titled, “Physiology and clinical use of melatonin,” which references over a hundred medical journal articles, if you have access to that.

  3. Jason B says:

    Since I can only find 1mg tablets in my area, would half a tablet be considered within the dosage tolerance discussed in this post? Thanks in advance.

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