Melatonin: The Good, the Bad, and the Ugly

Melatonin is available over the counter and is widely marketed towards children for sleep, so my patients and their families are often surprised when I caution them against using it. Like most things in medicine, there are both risks and benefits. After looking at all of the research, I’m not convinced that it works well enough in most kids to justify the risks of taking it, and I’ll outline my thoughts here. Let’s look at the good, the bad, and the ugly! And if you hear me out until the end, there’s even more “good” hiding there:)

The Good:

It’s super convenient that we’re able to supplement the body’s natural sleep hormone. Starting about 2 hours before falling asleep, when the eyes sense darkness, this hormone is secreted by a gland in the brain. Our nightly surge of melatonin is closely related to our internal sleep/wake clock, which is also known as our circadian rhythm. Studies have shown that taking melatonin can shorten the time it takes to fall asleep and lengthen total sleep time in healthy people, as well as those with disorders like insomnia. These studies are typically done in well-controlled settings (labs). Studies looking at melatonin use in the “real world” have struggled to consistently show positive effects. OK, so maybe melatonin isn’t a miracle drug, but when our family’s not sleeping we’ll try anything as long as it’s safe, right? Let’s move on to the bad…

The Bad:

Why doesn’t melatonin work better? Unfortunately, the timing of the dose is important and it’s difficult to time well. Our best guess is to administer melatonin 1-2 hours before sleep onset, but unfortunately real-life studies have been unable to show good consistent results from that general recommendation. To truly optimize when to give melatonin, we need to first determine an individual’s “Dim Light Melatonin Onset” time, or DLMO. This time varies in each person. To find it, a patient sits in a dark room and gives frequent saliva samples overnight. The time when the melatonin level starts to rise in the saliva samples is marked as the DLMO. Unfortunately, this testing isn’t widely available, and melatonin given without knowing an individual’s DLMO can be ineffective or even worsen sleep!

Our goal is always to use the minimal amount of any drug necessary to get the desired effect. Using more can increase the likelihood of side effects and interactions with other medications. Unfortunately, dietary supplements like melatonin are not regulated by the FDA like prescription and over-the-counter medications. A study of many different brands shockingly found the actual amount of melatonin in the supplement to be up to 83% less than, or 478% more than(!), what was labeled on the bottle. Unfortunately, we could be giving our kids almost 5X the amount of melatonin we think we’re giving them! And it isn’t just a few brands who have wacky doses. The advertised vs. actual amount of melatonin was mismatched (by more than 10%) in 71% of the brands that were studied! Can you believe it?!

So let’s say, optimistically speaking, without the DLMO test and not knowing how much melatonin you’re actually giving, it might be helpful on only some nights at best. That’s better than nothing, right? And studies have shown that it’s at least safe in the short-term, but what about the long-term, and theoretical risks? Here comes the ugly…

The Ugly:

Melatonin, being the hormone that it is, has been shown to affect another hormone important for fertility. Although we’re still unclear on exactly what these effects mean, we must acknowledge that there is some possible risk to a child’s endocrine system. This system is in charge of not only growth and puberty, but metabolism and blood sugar as well.

Another issue that bothers me about taking melatonin, besides the varying amounts of the active ingredient itself, is the presence of other unknown components in the supplement. Remember, companies often use fillers to make their products look and taste nice. I’m not too picky about what I give my kids so that might not be a deal breaker for me, except that the same study that measured the varying melatonin levels in different brands also found serotonin in 26% of those brands. Yes, serotonin. The feel good hormone that’s essential for mood regulation (as well as digestion and blood clotting). While it seems like giving extra serotonin might actually be helpful, too much of it can result in serotonin syndrome, with symptoms ranging from sweating and diarrhea to seizures and death. There are actually cases of this happening, and it’s definitely not a risk I want to take. For reasons like these, I tend to be cautious about supplements in general.

So those are the facts (as well as my very biased medical opinion) about giving melatonin for sleep. Although you’re probably discouraged about giving it at bedtime, wait! There’s more good news about melatonin that I didn’t mention before…

More Good News:

There are so many ways to help improve your child’s natural melatonin production! Melatonin is affected by both the brightness and duration of light exposure before bed. If possible, start dimming the lights in your house after dinner. Bathtime with a few nightlights in the bathroom can be very relaxing for kids, too! If your child needs a nightlight, using a red-colored light on the lowest setting will affect melatonin production the least. We love the Hatch Rest because it’s dimmable and you can set it to any color. Exposure to blue light is the most harmful for melatonin production. This is the type of light emitted by TV, tablet, and phone screens, which is why avoiding all screens for 2 hours before bed is so important. Room-darkening shades are also crucial, and so is getting outside to let those eyes soak in the natural daylight every single day!

What are your thoughts on melatonin? Do you have any great room-darkening tricks? I’d love to try them and share them!

Sleep well,


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