Are There Dangers to Using Melatonin for Sleep in ADHD?

Melatonin is a hormone produced by the body which tells it, among other things, when it is time to sleep.  Patients with ADHD often have sleep problems and are typically advised to take melatonin, which is currently sold over the counter as a dietary supplement.  Recently the media has featured multiple doctors discouraging the public from using melatonin, citing dangers such as possibly worsening sleep, cardiovascular and reproductive side effects long term.  So, how unsafe is melatonin?

Melatonin has been demonstrated in 4 clinical studies (some small, some not randomized) to help with sleep initiation in people with ADHD.  This isn’t entirely  impressive but when you consider that many people with ADHD also have difficulty with sleep phase regulation (a disorder of circadian rhythm, which is regulated by melatonin) and abnormal melatonin levels, it makes sense.  Melatonin has also been recommended by experts in ADHD for sleep for more than 10 years, which likely reflects some effectiveness, though exactly how much remains to be seen.

There are some known short term risks to taking melatonin.  For example, it’s possible it could cause tumors in a developing fetus (it does in some doses in rats), so pregnant women should avoid it.  It may lower the seizure threshold in epileptics.  It also has some drug interactions and short term side effects, like headaches and nightmares.  For this reason, a doctor should always supervise the use of melatonin and all of your doctors should know you take melatonin before prescribing other medications.

The long term risks to taking melatonin are a lot less well defined.  The main question comes up when you talk about how long melatonin is safe to use, and at what doses.  The reason melatonin is not regulated as a drug is because it can be found in many foods, such as meat, eggs, and nuts.  In other words, in low enough doses, taking it is as safe as eating (barring any harmful additives).  One to 3 mg of melatonin would be found in  approximately 100-300g (3.5 to 10.5 ounces) of tart cherries, which is probably more than most people could eat in a day but not a lot more.  The lowest doses of melatonin currently available are 0.3mg and 0.5mg.

Speaking of additives, not all melatonin is the same.  Since melatonin is regulated as a supplement and not a drug, the FDA does not tightly police how much melatonin is in any give preparation.  In one study from 2017, the amount of melatonin in a pill varied from the labeling by as much as 400% and that more than 70% of pills contained a dose more than 10% different from their label .  It is possible that consumers could get around this by purchasing only “pharmaceutical grade” melatonin verified by the United States Pharmacopeia (USP).  Furthermore, melatonin often comes with other “inactive” ingredients like gluten, artificial coloring, or other supplements like chamomile.  Many supplements marketed for children often contain flavoring and coloring, so checking for these ingredients is important if the patient shows sensitivity to them.

The main theoretical concerns about long term usage are based on the fact that we know melatonin is a hormone and many body processes depend on correct hormonal balances.  In animals, melatonin is involved in regulating reproduction in species that breed seasonally.   In rats, melatonin has been investigated as an anti-breast cancer agent, and it has been suggested that it could function as an anti-estrogenic hormone based on the fact that rats predisposed to cancer that are given melatonin have been observed to live longer and to develop fewer tumors.  Melatonin has also been demonstrated in human breast cell cultures to inhibit the enzyme aromatase, which is necessary for the production of estrogen from testosterone.

In human studies, however, chronic use of melatonin over 1-3 years has not seemed to change the rate children experience puberty.  Available studies are admittedly small, including one of adolescents with sleep phase delay syndrome (not receiving melatonin for ADHD related sleep onset insomnia) and one of children with ADHD.  The results of these studies were also not segregated by sex, which could be important if the issue is sex hormones.

Another concern is that many hormones are regulated by a feedback mechanism which shuts down hormone production if there are high enough levels of the hormone in the bloodstream.  This is certainly the case for many hormones in the body.  However, scientists have known for many years that melatonin is mostly regulated by the amount and time pattern of light reaching the eyes.  It is not at all clear that taking melatonin will cause the pineal gland to malfunction or atrophy, and pineal atrophy due to exogenous melatonin has never been documented in any study of any species. 

In many studies of patients with ADHD who take melatonin, however, the need for melatonin on a chronic basis is high.  In clinical studies usually only about 10% of patients are able to stop using melatonin after using it chronically, and about 70-85% continue to take it daily into long term follow up.    This does not mean that taking melatonin will cause a person to be unable to produce melatonin, however.  It could reflect an underlying deficiency in melatonin to begin with. 

People with ADHD who have sleep onset insomnia have a few alternatives outside of standard behavioral measures.  However, these all have their own side effects.

Clonidine, for example, works as a sedative, but cannot be taken as needed due to the fact that it can cause severe rebound hypertension (high blood pressure) which can (rarely) lead to stroke, heart attack, or kidney damage.  It also can cause hallucinations and nightmares, as well as headaches. 

Standard sleep medications often do not work well in patients with ADHD related insomnia, and almost all of them are potentially addictive and can interfere with sleep architecture during long term use.

The Bottom Line

You should only use melatonin under the supervision of a physician, and for an appropriate reason.   While it is unlikely to cause significant problems with judicious use, the issue of which doses of melatonin are safe to use long term needs more clinical study, especially in children.  Unfortunately, no such study is being done at this time, so it is likely that we will be living with uncertainty on this issue for a long time.  Lower doses are likely to be safer so it’s smart to start with 0.3-0.5 mg and only as needed after behavioral measures have failed.

References:

"MELATONIN: Uses, Side Effects, Interactions and Warnings." WebMD. WebMD, n.d. Web. 24 Apr. 2017.

Technical Resources International, Inc. "NTP Nomination History and Review: Melatonin." 4th ser. 73.31 (n.d.): n. pag. Mar. 1996. Web. 24 Apr. 2017.

Everything ADHD Medical Disclaimer

Everything ADHD Privacy Policy