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Benadryl for Sleep

With one in four Americans developing insomnia each year, there are millions of people misusing over-the-counter sleep aids to claw back those vital hours of sleep each night. Of this enormous number of unrested souls, there’s a mind-boggling number of people self-prescribing antihistamines to treat their insomnia.  

A simple google search for “Benadryl for sleep” will show there is a common misconception that Benadryl improves sleep, however, there is little to no evidence that this is true. Of the studies conducted, the findings recommend against using Benadryl for sleep. 

What is Benadryl?

Benadryl is the brand name for diphenhydramine, which is an antihistamine. Antihistamines are a type of drug that reduces allergy symptoms by blocking histamine compounds from working in the body. 

Antihistamines and antihistamine-pain medicine combinations are widely used and often misused remedies for insomnia. There is very limited evidence for the efficacy and safety of these medications. Antihistamines have the potential for serious side effects because of the way that they work.

How is Benadryl intended to be used?

Benadryl is an over-the-counter (OTC) medication typically used in patients who have allergy symptoms. These can include runny nose, hives, sneezing, itchy and watery eyes, and nose and throat irritation, among others. 

Benadryl can be helpful in patients who are having allergic reactions. As an antihistamine medication, it can cause side effects like drowsiness, blurry eyes, dry mouth, constipation, and trouble urinating. 

Why does Benadryl cause drowsiness?

The drowsiness that Benadryl causes is really just a side effect of the medication. Diphenhydramine is an antihistamine medication. 

Antihistamine medications block histamine from being used up by cells. This allows your brain to accumulate histamine. An abundance of histamine can make you feel sleepy. 

Why you should not use Benadryl for sleep

Benadryl’s sedative effects may help you fall asleep faster but it will not help you stay asleep. Benadryl will not increase your quality of sleep either. In fact, studies have shown that Benadryl is no more effective at helping you sleep than placebo and can cause many side effects. 

Side effects include dizziness, confusion, and decreased coordination. These side effects can lead to injury and are known to be worse in older adults. People often abuse Benadryl for sleep because of its drowsiness-inducing side effect. However, the sedative effects commonly carry over into the next day with a hangover-like effect, which can make next-day physical and mental functioning difficult, to say the least.

How Benadryl affects REM sleep 

When you reach the REM stage of sleep you have rapid eye movements and vivid dreams. Benadryl increases the amount of time it takes for your body to reach REM sleep and reduces the duration of this stage

This can lead to poor-quality sleep and impairment in attention, vigilance, working memory, and sensory-motor performance the following morning.

Benadryl tolerance

If you take Benadryl regularly for sleep it may seem like it works at first because the side effects can make you sleepy. However, Benadryl ultimately loses effectiveness over time as your body adapts to the medication. The drowsy side effect can weaken after only three days of regular use. Building tolerance can lead to people taking increasingly higher doses in order for them to feel tired. 

This can be extremely unsafe and even lead to overdose. Benadryl overdose can include extreme drowsiness, increased heart rate, blurred vision, confusion, seizures, and even coma in severe cases.

Benadryl May Increase Your Risk of Dementia

A recent study observed patients who used high doses of antihistamine medications like Benadryl. The results of the study showed an increased risk of dementia in patients who used higher doses of antihistamine medications. 

Sleep aid products containing Diphenhydramine (the active ingredient in Benadryl)

Most sleep aids in the OTC class are made with the antihistamine Diphenhydramine. These products include:

  • Benadryl 
  • Tylenol PM, Advil PM, Aleve PM
  • Unisom Sleep Sleep Gels
  • ZzzQuil

If not Benadryl, then what?

Benadryl is not a great option to improve sleep, particularly to get better sleep over time. Using Benadryl for sleep improvement will likely not be beneficial and can potentially cause serious side effects. 

Addressing the underlying causes of poor sleep requires a multi-pronged approach. 

Poor-sleep can be the result of issues relating to:

  • diet,
  • stress,
  • evening and night light exposure from electronic screens,
  • bad habits/ poor sleep hygiene, and 
  • other influences. 

Often the most impactful way to improve your sleep is to start out with lifestyle and sleep hygiene changes. While some of these can feel like big shifts, others can be surprisingly easy. Learn more...

OTCs aren’t the only way to improve sleep. Z’s creates customized natural sleep supplements that address specific sleep troubles. Learn more

Alternatively, there are many natural sleep aids out there. Learn more


  1. Benadryl (diphenhydramine hydrochloride) [Package Insert]. Johnson & Johnson Consumer Inc., McNeil Consumer Healthcare Division; 2018.
  2. Lie JD, Tu KN, Shen DD, Wong BM. Pharmacological Treatment of Insomnia. P T. 2015;40(11):759–771.
  3. Sateia MJ, Buysse DJ, Krystal AD, Neubauer DN, Heald JL. Clinical practice guideline for the pharmacologic treatment of chronic insomnia in adults: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2017;13(2):307–349.
    1. DOI: 10.5664/jcsm.6470
  4. Gray SL, Anderson ML, Dublin S, Hanlon JT, Hubbard R, Walker R, Yu O, Crane PK, Larson EB. Cumulative use of strong anticholinergics and incident dementia: a prospective cohort study. JAMA Intern Med. 2015 Mar;175(3):401-7.
    1. DOI:10.1001/jamainternmed.2014.7663
  5. Church MK, Church DS. Pharmacology of antihistamines. Indian J Dermatol. 2013;58(3):219–224.
    1. DOI: 10.4103/0019-5154.110832

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