Dayvigo (lemborexant) is a prescription oral tablet used in adults to treat insomnia (trouble falling or staying asleep). Dayvigo can cause side effects that range from mild to serious. Examples include tiredness, headache, and next-day sleepiness.

Some people may experience mild to serious side effects while taking Dayvigo. Examples of the most commonly reported side effects that caused people to stop taking Dayvigo during the drug’s studies include:

Not everyone will have these side effects from Dayvigo, but you may notice other possible side effects. For more information, keep reading.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Dayvigo, visit MedWatch.

Mild side effects have been reported with Dayvigo. These include:

Because Dayvigo can commonly cause next-day sleepiness, you should not drive or use machinery until you know how it affects you. Only take this medication if you can sleep for at least 7 hours afterward.

In most cases, these side effects should be temporary and easily managed. But if you have ongoing or bothersome symptoms, talk with your doctor or pharmacist. And do not stop taking Dayvigo unless your doctor recommends it.

Dayvigo may cause mild side effects other than those listed above. See Dayvigo’s prescribing information for more details.

* An allergic reaction is possible after taking Dayvigo, but this side effect wasn’t reported in studies.

Serious side effects from Dayvigo were uncommon during the drug’s studies.

Serious side effects reported with Dayvigo include:

The above list of serious side effects may not be complete, and not everyone will experience them. If you develop serious side effects while taking Dayvigo, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* See the “Side effects explained” section below to learn more about this side effect.
† An allergic reaction is possible after taking Dayvigo, but this side effect wasn’t reported in studies.

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Get answers to some frequently asked questions about Dayvigo’s side effects.

How do the side effects of Dayvigo compare with those of Ambien or Xanax?

A 2021 review of studies compared the safety of Dayvigo to other medications for insomnia, including Ambien (zolpidem). It found that Dayvigo may have side effects similar to those of other sleep treatments. However, this study noted that Dayvigo might make you less dizzy than Ambien but may make you more sleepy.

No studies have compared the side effects of Xanax (alprazolam) and Dayvigo. Both drugs can make you feel tired and less alert. Studies show that Xanax may cause moodiness, memory and speech problems, confusion, dry mouth, low blood pressure, and skin rash. But these side effects weren’t reported in Dayvigo’s studies.

Studies have also shown that Dayvigo does not cause physical dependence. (This is when your body gets used to a drug and needs it for you to function as usual.) So even with long-term Dayvigo use, patients won’t experience withdrawal symptoms (side effects caused by suddenly stopping a drug), which are common with Ambien and Xanax.

Is Dayvigo safe for long-term use?

Dayvigo can be used for both short- and long-term treatment. Studies show that it’s safe for up to 6 months. But if you’ve been taking Dayvigo for 7–10 nights and still aren’t seeing improvement, it’s important to discuss this with your doctor.

Does Dayvigo cause weight gain?

Dayvigo studies showed no evidence of weight gain. However, not getting enough sleep has been associated with gaining weight. Additional research is necessary to determine whether sleep aids can effectively aid in weight loss. Talk with your doctor if you’re concerned about weight loss or gain before taking a sleep aid.

Learn more about some of the side effects Dayvigo may cause.

Sleep paralysis

Sleep paralysis was an uncommon side effect reported in studies of Dayvigo. During the process of falling asleep or waking up, a person may experience temporary muscle paralysis, known as sleep paralysis. This may cause symptoms such as:

  • the inability to move or talk
  • sweating and chest pressure
  • a feeling that you’re in danger
  • the sensation of being smothered

Conditions that can increase the risk of sleep paralysis when taking this drug include:

What might help

If you have sleep paralysis during Dayvigo treatment, talk with your doctor. Because taking the lowest Dayvigo dose possible decreases your risk of sleep paralysis, they may recommend a dose change. Or they may have you switch to a different medication.

If you and your doctor decide you’ll continue taking Dayvigo, try following a bedtime sleep routine. This can include limiting caffeine and alcohol intake (if any), as well as not watching TV or other electronics 1 hour before bedtime.

Dreamlike hallucinations

Dreamlike hallucinations, also known as hypnopompic and hypnagogic hallucinations, were an uncommon side effect reported in Dayvigo studies. These types of hallucinations can happen when you’re partially awake, such as when falling asleep or waking up. Symptoms include:

  • having an intense feeling of confusion or fear
  • feeling like you’re flying, floating, or falling
  • hearing people talking or other sounds that are not real
  • seeing lifelike images of faces, bugs, animals, or people
  • seeing light flashes, changing patterns like a kaleidoscope

What might help

If you have dreamlike hallucinations during Dayvigo treatment, talk with your doctor. They’ll likely recommend a dose change or switch you to a different medication.

To lower the risk of hallucinations, try to:

  • get enough quality sleep
  • follow a regular sleep schedule
  • avoid alcohol and electronic device use 1 hour before bedtime

Allergic reaction

Like most drugs, Dayvigo can cause an allergic reaction in some people. But this side effect wasn’t reported in studies. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an oral antihistamine, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Dayvigo, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Dayvigo, they may have you switch to a different treatment.

Keeping track of side effects

During your Dayvigo treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Dayvigo affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before taking Dayvigo.


Dayvigo can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Dayvigo is a good treatment option for you.

Talk with your doctor about your health history before starting Dayvigo. Be sure to tell them if you’re under the age of 18 years or over the age of 65 years. You should also let them know if you’re pregnant or breastfeeding. (See “Pregnancy and breastfeeding with Dayvigo” below for more information).

You should also tell your doctor if you have any of the following:

Alcohol and Dayvigo

You should not take Dayvigo with alcohol because alcohol can worsen the side effects of this medication. These side effects include:

  • impaired driving
  • excessive sleepiness
  • inability to think or act clearly
  • risk of falls due to unsteadiness when walking

If you have questions about consuming alcohol during Dayvigo treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Dayvigo

Before starting Dayvigo treatment, it’s important to talk with your doctor if you’re pregnant, breastfeeding, or planning to be either.


If you’re pregnant or planning a pregnancy, talk with your doctor before starting Dayvigo treatment.

This drug has not been studied in pregnant people, so it’s not known whether it’s safe to take during pregnancy. However, your doctor will likely recommend that you do not take Dayvigo during this time.

If you take this drug while pregnant, consider signing up for the Dayvigo pregnancy registry by calling 888-274-2378. A pregnancy registry collects information about the safety of certain medications when taken during pregnancy.


It’s not known whether Dayvigo is safe to take while breastfeeding. But because this drug can be found in breast milk, your doctor will likely recommend that you not take it while breastfeeding. Dayvigo may cause excessive drowsiness in a breastfed child.

If you’re breastfeeding or planning to do so, talk with your doctor before starting this medication.

Due to the risk of misuse and dependence*, Dayvigo is a controlled substance in the United States. This means it has an approved medical use, but may be misused for other purposes. It also means government agencies, doctors, and pharmacists pay close attention to how the drug is prescribed and used.

If you have a history of alcohol or drug misuse, you may be more likely to become dependent on or misuse Dayvigo. Only take this drug exactly as prescribed by your doctor. Misuse increases the risk of overdose, which can lead to trouble breathing, coma, and even death.

Keep in mind that there’s no antidote for Dayvigo overdose.

* With misuse, a drug is taken in a way or for a reason other than how or why it was prescribed. Misuse can lead to dependence, which is when your body gets used to a drug and needs it for you to function as usual.

Like most drugs, Dayvigo can cause many side effects that range from mild to serious. However, most are temporary and go away after a few days to weeks. If you have questions about side effects that Dayvigo can cause, talk with your doctor.

Examples of questions to help get you started include:

  • To lower the risk of side effects, can I just take Dayvigo when I can’t sleep?
  • How long will Dayvigo stay in my system after I stop taking it?
  • Will daytime sleepiness from Dayvigo go away with time?
  • Will Dayvigo affect my memory?
  • Will I become dependent on Dayvigo?

To learn more about Dayvigo, see these articles:

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.