Expert consulted: Dr. Albert Stezin – because this question relates to medicine and sleep, I asked Dr. Stezin to provide the content for this article because he is a practicing medical doctor and qualified neuroscientist (verified here).
Personally, I suffer quite badly from allergies, and I also struggle to get to sleep.
And whenever I’ve taken Benadryl, I have found myself feeling a little more sleepy – which is good when taken at night but not so great when taken in the daytime.
But is there a definite link between taking Benadryl and feeling sleepy?
I asked Dr. Stezin his thoughts on this question, and here’s what he had to say based on his medical knowledge:
Taking Benadryl can make you sleepy because Benadryl is an antihistamine which means that this medicine blocks the action of histamine in the body – resulting in drowsiness because histamine promotes wakefulness.
Because of this sedating effect, many people often take Benadryl as a sleep aid.
However, it’s possible to build up a tolerance quite quickly to this medication, reducing its effectiveness.
So in the rest of this article, I have asked Dr. Stezin to come up with 17 potential sleep aid alternatives.
He’s also provided more details in regard to the relationship between Benadryl and sleep.
Related: see the best mattresses we have reviewed for improved sleep here.
Benadryl Makes You Sleepy By Blocking Histamine
Symptoms such as flu, cough, and allergic manifestations are very common in clinical practice and affect most people at least once every year.
These symptoms are caused when chemicals are released from inflammatory cells such as lymphocytes and mast cells.
It leads to manifestations such as sneezing, runny or itchy nose, redness and watering of eyes, difficulty in breathing, wheezing, cough, skin rashes, swelling of lips, tongue, eyes, or face, and sometimes diarrhoea.
The most common chemical implicated in these symptoms is histamine.
Histamine is widely regarded as the chief mediator of allergic and inflammatory responses in the body.
It also serves several other purposes such as the production of gastric acid, relaxation of blood vessels, constriction of the airway in the lungs, and as a neurotransmitter in the brain.
Benadryl is an antihistaminic medicine that opposes the release and action of histamine at the level of receptors.
It is a very potent drug and improves allergic symptoms and manifestations quickly.
However, it is known to cause side effects due to its widespread action on different parts of the body.
Normal Histamine Activity Promotes Wakefulness
As a neurotransmitter in the brain, histamine maintains a state of wakefulness and decreases sleep.
When Benadryl blocks the histamine receptors, it causes drowsiness and sedation by attenuating the wakefulness-promoting action of histamine.
In addition to its effect on histamine receptors, Benadryl has limited action on cholinergic and adrenergic receptors in the brain.
When Benadryl acts on these receptors, it also leads to drowsiness and sedation.
Although the sleep-related actions through these receptors are not very powerful, the multiple receptor-blocking actions of Benadryl may lead to significant drowsiness.
Benadryl, unlike many other antihistaminic medications, can cross the blood-brain barrier with ease and begin its effects on the brain quickly.
Benadryl Can Cause Daytime Drowsiness
Previous studies have reported people using Benadryl to have a decrease in sleep latency and improved sleep maintenance as short-term side effects.
People with short latency of sleep tend to sleep faster after going to bed and people with an improved maintenance phase of sleep tend to sleep longer without waking up.
While these are beneficial to sleep, the sleepiness and drowsiness due to Benadryl tend to persist longer and cause excessive daytime sleepiness, decreased concentration, increased reaction time, and poor cognition.
These can significantly affect your work performance. I usually advise my patients not to drive or use heavy machinery when on Benadryl.
The elderly are particularly prone to its effects, more so when concurrently taking multiple other medications.
In my personal experience and from a sleep expert’s perspective, a very common side-effect of Benadryl is a combination of drowsiness, fatigue, and dizziness.
This state is usually described by people as feeling dazed or groggy.
This may be due to inappropriate use of medicine, inter-individual differences in metabolism, and differences in sensitivity to the effect of Benadryl.
Benadryl May Make Children Hyperactive
In children, Benadryl can actually cause hyperactivity than sleepiness.
Since the consumption of Benadryl may affect people differently, I advise caution when using the drug.
Another important point to remember is that other brands may also contain the same active chemical (namely, dimenhydrinate) as is seen in Benadryl.
Other brands which contain dimenhydramine are Advil PM®, Midol PM®, Motrin PM®, and Sudafed PE Day/Night Cold®, to name a few.
It is often a component of cough and cold medications but may not be clearly mentioned prominently in the content list.
You should read the active ingredients listed on the pack or ask your pharmacist or doctor about the presence of Benadryl.
Antihistamine Medications Vary in their Sedative Potential
There are other antihistaminic medicines from the same class which produce sedative side effects.
These medicines are classified into highly sedative, moderately sedative, and mildly sedative drugs.
The medicines that are highly sedative include diphenhydramine, dimenhydramine (Benadryl), promethazine, and hydroxyzine.
The moderately sedative antihistaminics are pheniramine, cinnarizine, and cyproheptadine whereas the mild sedative effect is seen with chlorpheniramine and cyclizine.
These medicines are all classed under first-generation antihistaminics.
Second-generation antihistaminics are more popular due to the absence of sedative side effects.
Benadryl Can Make Adults Feel Sleepy for 5-6 Hours
The duration that Benadryl makes you feel sleepy can vary quite significantly between individuals – 5-6 hours seems typical for most adults – but feeling groggy can last for several days in some cases.
The sleep-inducing effect of Benadryl is a side effect of histamine receptor blockade in the brain.
Due to this reason, as long as Benadryl stays in the system, sleepiness or drowsiness will persist.
However, its severity will change as a function of time.
Benadryl Clearance Time Varies Depending On Age
Previous studies on the pharmacokinetics of Benadryl show that the half-life (time needed for half of the administered dose to be eliminated from the body) varies depending on the age.
In general, the half-life of Benadryl is about 13.5 hours in elderly adults, 9.2 hours in young adults, and 5.4 hours in children.
In most cases, the effect of the drug would persist for up to 2-3 half-lives.
Hence, the sleep-related effect of a single therapeutic dose of Benadryl can last for most of the day in young adults and the elderly.
The maximal side-effect is usually at the peak of the dose which is between five and six hours in adults and two hours in children.
That said, it should be noted that the normal dose of Benadryl for cough, cold, or allergy is three to four times a day (every 6th to 8th hour).
Hence, the sleep effects may persist for a very long duration.
In most circumstances, with regular use of Benadryl, the sleepiness and drowsiness do not last beyond a few days due to the development of tolerance.
In a previous study, 50mg of Benadryl taken daily produced sleep-related side effects which lasted only for 4 days.
The Effect of Sedation May Be Influenced by Other Medications
The duration of sleep effect also varies when multiple drugs are concurrently used.
The major drug groups that interact with Benadryl include pain medicines, antiepileptics, psychiatric medicines, potassium supplements, alcohol, and sleep medicines.
When concurrently used, the drowsiness and sleepiness may outlast the sleep-related side effects of either medicine.
However, whether tolerance develops when taken concurrently with another medicine is not yet known.
Benadryl Can Make You Sleepy the Next Day
Benadryl produces a long-lasting residual sedative effect after night time administered dose.
This excessive daytime sleepiness is a side-effect that is perceived as intolerable by most people taking Benadryl.
In my clinical practice, this is also the most commonly reported reason for non-adherence to medicine.
This ‘hangover effect’ has been established in many studies and is reported even after a single dose of Benadryl.
In addition to the patient-reported increase in total drowsiness score, electroencephalography studies have also revealed a slowing of brain activity after taking Benadryl.
The Cause of Benadryl Daytime Sleepiness is Not Clear
The exact cause of daytime sleepiness due to Benadryl is not very well understood.
It may be due to the ability of Benadryl to readily penetrate the blood-brain barrier and have a long-lasting effect or due to the blockade of receptors that uses acetylcholine or amine neurotransmitters.
This effect is also shared by most first-generation antihistaminics such as diphenhydramine, promethazine, hydroxyzine, and chlorpheniramine.
The daytime sleepiness is usually self-limited and resolves by the way of developing tolerance.
The development of tolerance has been proven using both subjective and objective measures of sleep and psychomotor performance sensitive to the sedative effect.
Studies show that tolerance to sedative action occurs with continued dosing than at any specific dose.
With 50 mg of Benadryl taken twice daily, tolerance develops within three to five days.
Beyond this time duration, most people do not experience daytime sleepiness.
However, inter-individual differences are common.
I usually ask people to take a break from their work for a few days when on Benadryl to avoid work accidents.
Benadryl Cream Won’t Normally Cause Sleepiness
Benadryl cream is used to treat pain and itching from insect bites, sunburns, rashes, and other minor skin conditions.
When used over a small area of the skin, it usually doesn’t get absorbed into the blood and spread all over the body.
So in most cases, Benadryl cream doesn’t cause excessive sleepiness.
However, if used extensively over large skin surfaces, especially in children, it can enter the bloodstream and cause sleepiness.
Benadryl Spray Won’t Normally Cause Sleepiness
Benadryl spray is used to treat allergic conditions that cause itching and pain over the skin, such as insect bites and skin irritation due to poison ivy, oak, or sumac.
In most cases, Benadryl spray causes only minor side effects such as skin irritation without any systematic side effects.
However, if Benadryl is sprayed over a large area of skin, there is a possibility of systemic absorption into the blood and the brain – this may make you drowsy and sleepy – but it’s quite uncommon.
It’s Not Safe to Take Benadryl Every Night to Sleep
Benadryl is often used by people as a quick solution to insomnia.
Some doctors also prescribe it for sleep problems.
Although it may work well in the short term, it not only is useless for chronic insomnia, it can even be harmful if used regularly.
There is evidence that people become tolerant of the sleep effects of Benadryl within one week of regular use.
This may cause people to take larger quantities of Benadryl and end up having significant side effects.
The major side effects of Benadryl are drowsiness, tiredness, constipation, dryness, incoordination, urinary retention, tremor, and blurred vision.
These side effects may be particularly more and cause functional impairment in older adults, young children, and pregnant women and are generally advised to avoid them as much as possible.
Another reason I do not recommend the regular use of Benadryl is because of the chance of becoming dependent on Benadryl for sleep.
Although the exact time duration for developing dependence is not known, a two-week interval is a reasonable approximation.
I always ask my patients to avoid taking Benadryl for more than a week to avoid dependence.
If a doctor feels that you should be on Benadryl for a longer duration, a scheduled drug holiday of one to two days in between may help.
In very rare cases of insomnia due to self-limiting conditions and patients refusing sleep medicine, I recommend taking Benadryl at a dose of 50 mg/day about 20 minutes before sleep time for less than one week.
Apart from these exceptional cases, taking Benadryl for sleep is not recommended.
17 Sleep Aid Alternatives to Benadryl
If you suffer from chronic insomnia, I recommend that you take sleeping medicines or alternate sleep aids other than Benadryl – as prescribed by YOUR doctor.
While Benadryl is available as an over-the-counter medication and may be an “easier” alternative than waiting for a doctor’s appointment and prescription for controlled substances (sleep medicine), I advise caution and recommend the following medicines and sleep aids ONLY under the guidance of your doctor.
Do NOT self-medicate with these substances.
1: Doxepin
Doxepin is a drug that comes under a class of medications called tricyclic antidepressants.
As the name of the class suggests, doxepin is an antidepressant medicine but it also has good sleep-promoting action.
It has high affinity and selectivity for histamine receptors even at low doses.
The sleep-promoting action is achieved through resynchronization of the circadian cycle rather than histamine blocking action.
An important feature of doxepin is that it is a non-habit-forming medication (no dependence) and doesn’t show tolerance.
Furthermore, studies also show it can increase both the duration of sleep and its quality.
Hence doxepin is an effective and safe alternative to Benadryl if prescribed and monitored by your own doctor.
2: Melatonin
Melatonin is a hormone that is involved in the regulation of sleep and wakefulness.
It has been commercially used in the treatment of chronic insomnia.
While the American Academy of Sleep Medicine (2017) and the American College of Physicians (2016) do not recommend the use of melatonin as a first-line treatment, it is available over-the-counter and is a popular sleep supplement.
Furthermore, previous studies have demonstrated that supplementation with melatonin improves the quality of sleep in people with sleep disorders.
Melatonin at a dose of 3 to 10 mg can be safely taken under the guidance of your doctor.
Click here for more details on melatonin.
3: Ramelteon
Ramelteon acts on the melatonin receptors selectively and is useful for the treatment of chronic insomnia with difficulty in the onset of sleep.
It has no sedating effect but improves sleep by modulating the regulatory mechanisms within the hypothalamic nuclei.
It also has no abuse liability.
It is recommended to take an 8 mg tablet about 30 minutes prior to sleep time.
There is no clear recommendation regarding the duration of treatment although longer durations are generally well-tolerated due to the absence of dependence.
Whenever I prescribe I keep the duration between 1 week and 2 months depending on whether insomnia is acute or chronic (> 1-month duration).
4: Zolpidem
Zolpidem is a widely prescribed medicine in clinical practice for sleep problems.
It is usually prescribed for moderate to severe insomnia.
It is highly effective when used in the short term but has certain specific side effects that you should know.
The most common ones are a metallic taste in the mouth and an increase in sleepiness during the daytime.
While it decreases the latency of sleep, it often leads to an increase in episodes of waking up during sleep.
An extended-release version of zolpidem may help with improving the sleep maintenance phase.
If you take zolpidem, you should ensure that you get 7 to 8 hours of sleep.
If not, you may feel groggy, confused, and may have recurrent falls.
Rarely, it can also lead to sleepwalking and sleep talking.
The maximum duration of use is approximately four weeks, but the shorter the better.
Recently, the FDA has approved the use of an oral spray formulation called Zolpimist for short-term use.
5: Eszopiclone
Eszopiclone is a non-benzodiazepine sleep medicine that improves sleep quality by decreasing latency and improving the maintenance of sleep.
Hence it is useful for insomnia with sleep onset or sleep maintenance insomnia.
It has a long half-life of approximately six hours.
The starting dose is 1 mg every night increased up to a maximum of 3 mg.
It has a rapid onset of action and should be taken immediately before bed.
It should be avoided in patients older than 65 years.
6: Valerian Root
Valerian root extract has sedative and anti-anxiety properties.
Valerian extracts contain valepotriates, monoterpenes, sesquiterpenes, carboxylic compounds, valerenic acid, and valerenol.
These molecules act on GABA receptors, modulate their activity, and increase the amount of GABA which in turn increases sleep.
Few studies have also reported valerian to interact with serotonin and adenosine which are neurotransmitters implicated in the regulation of sleep and mood.
The sleep benefits associated with valerian extract have been proven in clinical trials.
Upon regular use, it improves sleep quality by decreasing night awakenings and sleep latency.
7: Magnesium
Magnesium produces a sleep-promoting and relaxing effect by regulating GABA and melatonin levels.
Combinations of magnesium and vitamin B have been shown to be useful in the treatment of insomnia in prior research.
Magnesium supplements are available as over-the-counter medicines in pharmacies.
The major side effects associated with the use of magnesium supplements include diarrhoea, cramping, and nausea.
If there is a sudden change in the levels of magnesium in the blood, it can also cause irregular heart rate.
Hence, caution is advised if you have heart disease.
Speak to your doctor before taking magnesium supplements
8: Chamomile
Chamomile has been used as a sleep promoter in the form of tea and essential oil aromatherapy for many centuries.
Chamomile has a moderate sedative and tranquilizing effect which can allay anxiety and induce sleep.
Although the specific mechanism of sedative action is not known, it is believed to be related to the action of flavonoids called apigenin on the benzodiazepine receptors.
You should make a strong chamomile tea to get the sleep-promoting effect.
Click here for a guide on preparing chamomile tea for sleep.
9: Glycine
Glycine and other glycine-rich products such as bone broth, poultry, fish, spinach, kale, and bananas are known to improve objective measures of sleep quality.
If you are taking supplements of glycine, 3 mg tablets/sachet one hour before sleep can help.
Studies show that people on glycine fall asleep faster and have no sleepiness during the daytime.
10: Lavender
Lavender has an antidepressant and sedative effect and has been used to calm the nerves and stabilize mood disorders.
Studies show that lavender aromatherapy reduces stress and anxiety, creates a positive mood, encourages daytime alertness, and produces a more restful nighttime sleep.
The sleep, cognitive, and mood actions are due to a volatile terpene called linalool which moderates the levels of glutamate, GABA, acetylcholine, and dopamine.
For sleep benefits, either use lavender essential oil in aromatherapy or make lavender tea using plant parts.
The essential oils should not be consumed as it is toxic to humans and the preparation process introduces toxic chemicals into the oil.
Click here for more details on using lavender to help with sleep.
11: Ashwagandha
Ashwagandha is a medicinal herb widely used in Indian and African medicines as a cure for insomnia.
Recent studies show that it decreases sleep latency and improves the quality of rest.
The sleep benefits are due to triethylene glycol in the leaf extract which instills a sense of peace and calm and eases you into a state of relaxation and sleep.
You should take this preparation carefully as there are not many studies on its interaction with other medicines.
12: Holy Basil
Basil is an herb which many naturalists claim can combat sleep disorders.
It has been used as an herbal remedy for a number of health conditions such as nausea, breathing difficulty, allergy, skin irritations, and sleep.
It is believed to have many ‘adaptogens’, which are molecules that help the body adapt to stress.
These chemical molecules may be responsible for the sleep benefits associated with Holy basil.
13: Wild Lettuce
Wild lettuce has a chemical compound called lactucarium which has analgesic and sedative properties.
It is widely used in homeopathy for the treatment of anxiety and mild insomnia.
Since there are fewer scientific studies about wild lettuce, its safety in different medical conditions are poorly understood.
I advise you to speak to your healthcare professional before taking wild lettuce extract as a sleep aid.
Click here to discover some of the myths about lettuce water/tea and sleep.
14: Hops
Hops have a sedative molecule called methylbutenol.
Physicians have used hops as a potent remedy for sleeplessness since the early 1900s.
The strong fragrance of the flower is believed to induce sleep and it was common for physicians to advise leaving sachets of hops under pillows for good sleep.
It is also useful as a brewed potion but is very bitter to taste.
You may brew it with other sleep-producing plant products such as chamomile to mask the taste.
However, you should always check with your doctor if combining herbal products would cause a harmful interaction.
15: Peppermint and Lemon Balm
Peppermint is not a potent sedative but has a natural muscle relaxant action that decreases muscle tension.
It also helps in digestion and is useful for a bloated stomach.
Hence, they impact sleep indirectly.
Furthermore, they add taste to herbal teas which are notoriously insipid or have offensive tastes.
If you do not like peppermint, lemon balm is another plant from the mint family which shares similar properties but with a citrusy flavor.
16: St. John’s Wort
St John’s wort is often used in the treatment of mood disorders and insomnia.
Its action is related to its ability to increase the levels of serotonin in the brain.
In clinical studies, St John’s wort increases the REM stage of sleep and deep sleep duration.
St John’s wort is known to interact with a large number of drugs.
Hence, you should consult your doctor before you decide to take this as a sleep aid.
17: Cognitive Behavioural Therapy
Cognitive behavioural therapy is the preferred first-line therapy in people with chronic insomnia.
This therapy involves allaying anxiety and thoughts that are associated with insomnia, addressing unreasonable expectations about the duration of time spent sleeping, and resolving misinformation regarding the effects of perceived or actual sleeplessness.
It also involves teaching techniques useful for sleep such as meditation, mindfulness, and progressive muscle relaxation.
It is not effective for all people and may not be readily accessible due to the unavailability of trained therapists.
Click here for more information about getting to sleep with anxiety and OCD.
Summary: Benadryl Shouldn’t Be Used as a Sleep Aid
Benadryl has sedative properties due to its antihistaminic action.
The sleep-inducing actions are usually short-lasting.
On regular consumption, tolerance develops within 3 to 4 days requiring larger doses for the same sleep benefits.
Hence, Benadryl is not recommended as a sleeping aid.
Alternatively, for the treatment of chronic or acute insomnia, you should speak to your doctor about taking a short course of sleep medicines or sleep-promoting herbs.
Always consult a doctor or a registered medical practitioner before taking the listed sleep alternatives.
Sources and References
[1] Larry Culpepper, Mark A. Wingertzahn. Over-the-Counter Agents for the Treatment of Occasional Disturbed Sleep or Transient Insomnia: A Systematic Review of Efficacy and Safety. Prim Care Companion CNS Disord. 2015; 17(6): 10.4088/PCC.15r01798
[2] Sandrah-Ann M Almond , Madelyne J Warren , Kayce M Shealy , Tiffaney B Threatt, Eileen D Ward. A Systematic Review of the Efficacy and Safety of Over-the-Counter Medications Used in Older People for the Treatment of Primary insomnia. Sr Care Pharm 2021 Feb 1;36(2):83-92.
[3] Dieter Riemann, Chiara Baglioni, Claudio Bassetti, et al. European guideline for the diagnosis and treatment of insomnia. J Sleep Res. 2017 Dec;26(6):675-700. doi: 10.1111/jsr.12594.
[4] Jungyoon Kim, Suji L Lee et al. Natural Products from Single Plants as Sleep Aids: A Systematic Review. J Med Food. 2018 May;21(5):433-444.
[5] S. Guadagna, D. F. Barattini, S. Rosu, L. Ferini-Strambi. Plant Extracts for Sleep Disturbances: A Systematic Review. Evid Based Complement Alternat Med. 2020; 2020: 3792390.
Medical Disclaimer
No part of this post or website offers medical advice – always consult with your doctor for the best guidance.
Image Attribution and Licensing
Main image: ‘Herbal Medicine’ by Nikolaydonetsk (used with permission and commercially licensed through Envato Elements).
Dan is the founder and head content creator at Bedroom Style Reviews.
He has been working as a professional online product reviewer since 2015 and was inspired to start this website when he ended up sleeping on a memory foam mattress that was too soft and gave him backache.
Through in-depth research and analysis, Dan’s goal with this website is to help others avoid such pitfalls by creating the best online resource for helping you find your ideal mattress, bedding, and bedroom furniture.
Dan is a qualified NVQ Level 2 Fitness Instructor with 6 years’ experience helping clients improve their health through diet, exercise, and proper sleep hygiene.
He also holds several college and university-level qualifications in health sciences, psychology, mathematics, art, and digital media creation – which helps him to publish well researched and informative product reviews as well as articles on sleep, health, wellbeing, and home decor.
Dan also has direct personal experience with insomnia, anxiety, misophonia (hypersensitivity to sounds), and pain from both acute and long-standing sporting injuries – he enjoys writing insightful articles around these subjects to help fellow sufferers of such conditions.
Learn more about Dan here.