How Much Melatonin Is Really in That Supplement?

Supplementary melatonin is the fourth most popular natural product used by adults in the United States and the second most popular given to children.

But supplements like melatonin are not subject to the same quality controls as prescription medications. A new study of melatonin sold over-the-counter shows that information on the label often does not reflect the content of the product.

Melatonin content may differ from amount listed on labelSupplementary melatonin is the fourth most popular natural product used by adults in the United States and the second most popular natural product given to children. It can change the timing of sleep, ease jet lag, and help night owls shift to an earlier sleep schedule. Occasionally it’s used to correct a melatonin deficiency, or for insomnia (although for insomnia it’s unlikely to yield much benefit).

But supplements like melatonin are not subject to the same quality controls as prescription medications. A new study of melatonin sold over-the-counter shows that information on the label often does not reflect the content of the product. Here are the details:

Testing for Melatonin and Serotonin

The researchers tested the contents of 30 different melatonin supplements sold in Canada (likely similar to melatonin sold in the United States). Among them were products with 16 different brand names (the names were not published), in 5 different strengths, and in 7 different formulations, some containing herbal additives and others without. They wanted to see how closely the amount of melatonin listed on the label matched the melatonin content of the actual supplement.

They also screened for serotonin. Serotonin is a precursor of melatonin found in the herbal extracts with which commercial melatonin is often combined.

Variation in Melatonin Content

Holy cow! The actual melatonin content of the supplements varied quite a lot from the content listed on the labels. Some labels overstated the amount of melatonin contained in the product. The worst offender here was a capsule listed as containing 3 mg of melatonin that actually contained about 0.5 mg.

Other labels greatly underrepresented the amount of melatonin in the product. The worst offender here was a chewable tablet listed as containing 1.5 mg of melatonin that actually contained nearly 9 mg. (This is particularly concerning since chewable tablets are most often taken by children.)

Not only was the melatonin content of the product off by more than 10% of the listed content in about 71% of the products tested. As shocking as this may seem, the melatonin content varied widely from lot to lot of the same product. While the first lot of the chewable tablets cited above contained nearly 9 mg of melatonin, the second lot contained only 1.3 mg. That’s a variation of 465%.

Variation Could Be a Problem

Does the dose of melatonin you take matter? To some extent, yes, say the authors of a commentary on the study. Suboptimal doses might be ineffective. Taking too low a dose might lead you to believe melatonin didn’t work when a higher dose would.

Higher-than-advisable doses could lead to undesirable side effects. Too high a dose would be risky for people taking medications that interact with melatonin, or those who are pregnant or have diabetes. And the long-term effects of supplementary melatonin on prepubertal children are still unknown.

Overall Conclusions

So what are we to do with this information in light of the fact that the researchers haven’t revealed the names of the products they studied? Here’s a summary of what they learned, which, if you take or are contemplating taking melatonin, is worth consideration.

  • The least variable products overall were those containing the simplest mix of ingredients: the tablets or sublingual tablets with melatonin added to a filler. Apparently, added herbal extracts tend to make products more variable.
  • Except for the chewable tablet cited above, capsules generally showed the greatest lot-to-lot variability in melatonin content. (However, the melatonin content of some capsules was within 10% of the content listed on the label).
  • Unexpectedly, the three liquid products tested showed fairly high stability and low lot-to-lot variability.
  • The melatonin content of products listed as containing 1 or 1.5 mg of melatonin was quite a bit more likely to diverge from what was claimed than were products listed as containing higher doses. Products purportedly containing 1.5 mg of melatonin were also quite a bit more variable from lot to lot.

Unlisted Serotonin

Eight of the 30 products tested contained unlisted serotonin. While the presence of serotonin is hard to explain in supplements containing just melatonin and a filler, it might be expected in supplements containing herbal extracts. In one such product, a capsule listed as containing 3 mg of melatonin plus lavender, chamomile, and lemon balm, the serotonin content was assessed at 74 micrograms.

Serotonin raises significant health concerns if taken in excess, the Canadian authors say. It can lead to a condition called serotonin syndrome, which can be mild or fatal and “exacerbated by interactions with other medications, such as selective serotonin reuptake inhibitors and the analgesic tramadol.”

I’d like to see the content of supplementary melatonin sold in the U.S. tested and reviewed by brand and formulation. ConsumerLab? Otherwise for people using over-the-counter melatonin (or interested in trying it) it’s a kind of Wild West situation when it comes to knowing which brand to buy. Pharmacists and doctors who prescribe melatonin may be better informed. Comments?

Sleep and Health Benefits of Melatonin

As a treatment for chronic insomnia, melatonin supplements disappoint. Internal secretion of melatonin, the hormone of darkness, begins to rise some two hours before you fall asleep. Adding to it with a melatonin supplement is often redundant.

But there’s increasing evidence that melatonin supplementation is effective for some sleep problems and may also help to treat and/or avert serious health conditions. Here’s a summary of the benefits.

Melatonin ineffective for insomnia but effective for other sleep problemsAs a treatment for chronic insomnia, melatonin supplements disappoint. Internal secretion of melatonin, the hormone of darkness, begins to rise some two hours before you fall asleep. Adding to it with a melatonin supplement is often redundant.

But there’s increasing evidence that melatonin supplementation is effective for some sleep problems and may also help to treat and/or avert serious health conditions. Here’s a summary of the benefits.

Shifting the Timing of Sleep

Supplementary melatonin can be used as a chronobiotic—an agent that brings about a phase adjustment of the body clock. It can shift the timing (but not the duration) of your sleep. So it’s an effective therapeutic in at least two situations:

  1. As a jet lag remedy: Eastward travel across several time zones is difficult. Your body clock has to shift forward several hours until sleep syncs up with darkness in the new time zone. A melatonin tablet taken before a late afternoon or early evening departure (together with reduced light exposure) may help to initiate this phase advance and serve as a jet lag remedy. From day 1 you’ll fall asleep earlier and wake up earlier, starting out on the right foot.
  2. As a maintenance therapy for night owls: If you come alive in the evening and can’t get to sleep till 2 or 3 a.m., chances are your body clock runs late. Instead of completing a daily period every 24 hours, a daily period for you may be closer to 25 hours and even longer. The medical diagnosis for this problem is delayed sleep phase disorder, or DSPD. People with DSPD have a tough time getting up for early morning classes and work. The solution is twofold: bright light exposure in the morning and a daily melatonin supplement taken around dinnertime. (For details see this blog post on DSPD.) Recently, melatonin was found to be quite effective in helping adolescent night owls fall asleep earlier so they could rise ‘n’ shine in time for early morning classes.

Correcting a Melatonin Deficiency

Melatonin is secreted by the pineal gland. It helps to create the relatively strong biological rhythms that put you to sleep and keep you sleeping through the night. But melatonin rhythms can weaken with age. The following may be involved:

  • degeneration of neurons in the body clock
  • deterioration of neurons connected to the pineal gland
  • calcification of the pineal gland

All of these factors are associated with melatonin deficiency and will make it harder to fall and stay asleep.

How can you know if you’re deficient in melatonin? An easy way is to test for the main melatonin metabolite in a urine sample collected during the first void of the morning. Testing for melatonin in the saliva and the blood is more involved. Home test kits are available, but you’re more certain to get accurate results from tests ordered by a doctor.

Older adults deficient in melatonin may find their sleep improves when they take a daily melatonin supplement. Timed-release melatonin is now available over the counter in the United States. Particularly if your problem is sleep maintenance insomnia (you wake up several times at night), a timed-release supplement will probably be more effective than immediate-release tablets, which exit the system fairly quickly.

Other Benefits of Melatonin Supplementation

Melatonin may have other health-protective effects. It’s been found to act as a powerful antioxidant in laboratory tests. In a review paper published last year, Lionel H. Opie and Sandrine Lecour cite evidence that melatonin may be effective in helping:

  • lower hypertension
  • reduce damage to body tissue after a heart attack
  • protect against, and reduce cell death following, strokes
  • prevent the adverse health effects of obesity
  • treat type 2 diabetes

Weaker evidence suggests that melatonin may help combat some cancers, including prostate and breast cancer.

If you’re a garden-variety insomniac like me, you may not think much of melatonin. But don’t you have to love it a little bit for all the things it can do?

If you’ve tried melatonin for sleep or some other reason, how did it work?