Medically reviewed by Mary Lucas, RN
Written by Our Editorial Team
Last updated 10/06/2020
From time to time, just about all of us will experience a night in which our bodies just won’t let us fall asleep at a normal time.
Dealing with insomnia, whether temporary or recurring, can be stressful. Not only is it frustrating to spend hour after hour in bed without being able to fall asleep, but the lack of sleep that occurs after a night of insomnia can zap your energy, focus and wellbeing.
To deal with occasional bouts of insomnia, many people turn to over-the-counter antihistamines such as diphenhydramine, the active ingredient in Benadryl®.
Although antihistamines aren’t designed to treat insomnia, the drowsiness they induce may make it easier to fall asleep, making them a convenient now-and-then treatment option that most people already have inside their medicine cabinet.
Benadryl is a popular first-generation antihistamine that does cause drowsiness as a side effect, partly because it's less likely to affect the natural histamine produced by our brain.
That's where the association comes from — because of the tight association between antihistamines like Benadryl and drowsiness, it's a pretty common connection people experiencing light levels of insomnia make to help them curb their sleep problems.
However, they aren’t the best option for treating insomnia.
Not only are they less effective than other sleep aids, but they may also be more likely to lower your sleep quality and cause certain side effects.
Below, we’ve dug into the data behind how Benadryl and other antihistamines cause you to fall asleep easier. We’ve also listed a range of safer, healthier alternatives to Benadryl that can help you fall asleep if you’re prone to difficulty sleeping.
Benadryl is a type of medication called an antihistamine. It contains an active ingredient called diphenhydramine. Diphenhydramine is an old, well-studied medication that first came onto the market in the 1940s and has been widely used in the decades since.
diphenhydramine is typically used to treat the effects of allergies. It’s also used for certain cold symptoms, motion sickness and, in some cases, as a treatment for sleep difficulties.
Diphenhydramine works by blocking the effects of histamine — a neurotransmitter responsible for numerous processes in the body.
Histamine mediates your body’s response to allergens by triggering an inflammatory response in your body’s nasal mucosa.
When you feel sick or have an allergic reaction, histamine’s effects on your body may cause you to develop a runny nose, itchy skin, watery eyes and other common allergy symptoms.
This is why Benadryl is often used to treat allergies and cold symptoms. By blocking the effects of histamine, it makes the symptoms of allergies or a cold less severe and easier to deal with.
Interestingly, histamine is also responsible for regulating your sleep-wake cycle. By binding to the brain’s H1 histamine receptors, medications containing diphenhydramine not only make it easier to deal with cold symptoms, but can also make you feel drowsy and ready to sleep.
Benadryl isn’t the only cold and allergy medication that contains diphenhydramine.
You can also find diphenhydramine in a lot of other common medications, including Advil PM®, Midol PM®, Motrin PM®, Sudafed PE Day/Night Cold® and certain cough medicines.
Numerous studies of diphenhydramine show that it’s effective as an over-the-counter sleep aid for treating insomnia.
For example, a 1983 study found that people with mild to moderate insomnia fell asleep faster after using diphenhydramine compared to a placebo, and reported a higher level of restfulness, despite experiencing some side effects.
Another study from 1990 on psychiatric patients found that diphenhydramine improved sleep in people with insomnia when given at a range of doses, all without any symptoms suggestive of drug dependence.
In short, there’s a reasonable amount of scientific evidence showing that diphenhydramine, the active ingredient in Benadryl and several other allergy medications, could make it easier to fall asleep if you’re prone to insomnia.
Unfortunately, although diphenhydramine may be effective at inducing sleep, it has several side effects that make it a poor sleep aid overall.
First, diphenhydramine is only safe to use as a sleep aid in the short term. We’ve explained the reasoning behind this a little further down the page.
Second, although diphenhydramine might make you feel drowsy and help you fall asleep faster, it often causes next-day drowsiness and a hangover-like feeling in the morning. This means that while you might fall asleep faster, you may wind up feeling worse the next day.
Third, antihistamines like diphenhydramine may affect your sleep quality, meaning that although you might sleep for longer than you would without medication, you may not feel as refreshed as you should after getting a full night’s sleep.
Fourth, your body can develop a tolerance to medications like diphenhydramine, even in just a few days.
In a 2002 study, researchers found that although diphenhydramine 50mg worked well as a sleep aid for several days, after four days it was no more effective than a placebo.
Even though Benadryl and other medications containing diphenhydramine are generally considered safe in the short term, there's some evidence that diphenhydramine could contribute to cognitive decline when used over the long term.
This side effect appears to be most common in the elderly.
In a 2001 study, researchers found that elderly patients given diphenhydramine were more likely to show inattention, disorganized speech and altered consciousness than those not given the medication.
There’s also evidence that medications with anticholinergic effects like diphenhydramine may be linked to the development of dementia.
There are numerous alternatives to Benadryl that can help you get a better night’s sleep. Some of these are over-the-counter treatments that you can buy online or from your drug store, while others are prescription medications.
One over-the-counter sleep aid that can be a helpful alternative to Benadryl is melatonin. It’s a hormone produced by your body to regulate the sleep-wake cycle. Like diphenhydramine, it’s helpful as a short-term treatment if you find it difficult to fall or stay asleep.
Melatonin is a supplement rather than a medication, meaning you can purchase it without any prescription. It’s one of several ingredients in our Sleep Gummy Vitamins, which are designed for relief on occasional restless nights.
Although study data is limited, melatonin also doesn’t seem to negatively affect deep sleep or sleep quality.
We’ve dug into the science behind melatonin in more detail in our guide to using melatonin for sleep, which looks at how melatonin measures up next to other sleep aids.
Beyond melatonin, there are numerous natural sleep aids that may help you to fall asleep and stay asleep easier.
Overall, the science behind these products is mixed, although some appear to show promise.
We’ve listed and compared these in our guide to natural sleep aids.
If you frequently suffer from insomnia, you may benefit from using a prescription medication to improve your sleep. Several prescription medications are available to treat insomnia, including newer medications that improve sleep without being habit-forming. Options include:
Doxepin. Originally designed as a treatment for depression, doxepin is also effective as a treatment for insomnia at low doses. As a non-habit forming medication, doxepin is an effective, safe alternative to both Benadryl and older sleeping pills.
Studies of doxepin show that it can increase sleep duration and sleep quality, all without reducing deep sleep.
Ramelteon. Ramelteon is a prescription medication that works by binding to the body’s melatonin receptors. It’s prescribed to treat sleep-onset insomnia — a form of insomnia that makes it difficult to fall asleep in a normal amount of time.
Studies of ramelteon show that it’s effective at reducing sleep onset time in people with insomnia, without any significant habit-forming potential.
Zolpidem (Ambien®). Well known and widely prescribed, zolpidem is a popular sleeping pill. Studies show that it’s highly effective at helping people with insomnia enjoy better sleep, albeit with some side effects.
Like many other sleeping pills, zolpidem is intended for short-term use only, meaning it may not be the best choice if you have chronic insomnia.
Eszopiclone (Lunesta®). Eszopiclone is a prescription sleeping pill that works similarly to zolpidem. However, it’s approved by the FDA for use as a long-term treatment for sleep difficulties for up to six months at a time.
Because these medications require a prescription, you’ll need to talk to a doctor before you can purchase or use any of them.
Although antihistamines like Benadryl will make you feel sleepy, they’re not a great choice when it comes to treating insomnia. Not only can they affect your sleep quality, but they’ll also become less effective very quickly, meaning you may not notice any benefits if you use them often.
Instead of relying on Benadryl for sleep, consider talking to your doctor about using a safer and more effective medication. For mild insomnia, you can also consider an over-the-counter option such as melatonin or a herbal sleeping aid.
Finally, insomnia is often treatable by making changes to your habits and lifestyle. We’ve listed a variety of proven tactics that you can try to improve your sleep in our guide to science-backed ways to get better sleep.