Lesvos Greece

The Question: How do over-the-counter sleep aids like ZzzQuil help me fall asleep?

The Answer: These days there is a wide variety of OTC medications filling pharmacy shelves that are advertised as sleep aids for those struggling to drift off at the end of a long and stressful day. However, the active ingredient in many of these drugs is one that will be familiar to people with allergies: antihistamines. The only difference is often marketing, according to sleep medicine experts.

Looking at the label, one can see that the active ingredient in ZzzQuil is diphenhydramine, which is more commonly known as the active ingredient in Benadryl, according to Shalini Paruthi, M.D., a fellow of the American Academy of Sleep Medicine and the director of the Pediatric Sleep and Research Center at Cardinal Glennon Children's Medical Center. In other words, the antihistamine that has helped relieve us of sneezing and itchy, watery eyes for decades is also being used to address our disturbed sleep.

"We do know that antihistamines can certainly make people feel sleepy, and so we do find diphenhydramine in a number of over-the-counter medications that advertise as helpful for people trying to fall asleep at night," said Dr. Paruthi. "But it's important to know that when we use something like diphenhydramine to help us sleep at night, we’re actually using it for its side effect – not its treatment, which is to fight allergies."

Little long-term research exists on the risks associated with continuous use of OTC sleep aids, but Dr. Paruthi said the main concern among physicians and sleep specialists is the potential for dangerous drug interactions with other medications. But for a person in good health who does not take other prescription medications, this risk is much lower. Instead, the danger for this group is that they'll experience drowsiness that lasts longer than the amount of time they intended to sleep.

Trying an over-the-counter solution to get through a particular rough patch can be fine, said Dr. Paruthis. "After a couple of weeks, if they aren’t experiencing better sleep, that is a good time to see their physician or consult a sleep medicine expert."

In addition to diphenhydramine, the most common active ingredients in OTC sleep aids include melatonin (a synthetic version of the naturally-occurring hormone that signals to our bodies that it time for bed) and tryptophan (the component commonly associated with Thanksgiving Day turkey). Herbal remedy alternatives typically include valerian, chamomile or kava, according to Dr. Paruthi.

At the end of the day, the most important question people considering using an OTC sleep aid can ask themselves is: "Do I really need it?"

Dr. Paruthi explained that it's much better to check in with your current lifestyle habits before resulting to a chemical solution. Waking up at a consistent time, eating a balanced diet, exercising, and setting a healthy bedtime routine can often alleviate the insomnia-like symptoms so many people experience in our "constantly on" society. It's also important to rule out serious sleep conditions as the potential cause of your inability to rest. Dr. Paruthi recommends visiting a physician or a board-certified sleep specialist to test for problems like obstructive sleep apnea if insomnia is a persistent and serious problem for you. Those conditions left undiagnosed can wreak far more havoc on your health than ZzzQuil.

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