Mirtazapine is an antidepressant drug that has a sedative effect. Although not a standard treatment for sleeping problems, some doctors prescribe mirtazapine for insomnia because of the drug’s ability to induce drowsiness. Mirtazapine is one of several antidepressant medications that are sometimes used to try to improve sleep. 

We discuss mirtazapine’s effects on sleep and explain who may be most likely to benefit from taking it. We also describe the typical dosage of mirtazapine, its potential side effects, and alternative ways to improve sleep. 

What Is Mirtazapine?

Mirtazapine is a drug primarily used to treat major depression. Mirtazapine is considered an atypical antidepressant because it is generally only prescribed for depression if standard antidepressants have not been effective. Mirtazapine helps regulate mood by increasing the release of certain chemicals in the brain, including serotonin. 

Mirtazapine has been approved by the FDA to treat depression since 1996. In addition to its approved use, mirtazapine has also been prescribed off-label in the treatment of other issues, including: 

  • Generalized anxiety disorder 
  • Post-traumatic stress disorder
  • Panic disorder
  • Tension-type headaches
  • Fibromyalgia
  • Insomnia

Does Mirtazapine Affect Sleep?

Sleepiness is a common side effect of mirtazapine. Up to 53% of people who take mirtazapine report increased drowsiness. This may be due to the way mirtazapine affects brain receptors for chemicals like serotonin and histamine. 

Because of its sedative effect, some researchers started to investigate mirtazapine as a way to try to improve sleep. Mirtazapine has shown promise as a treatment for people who have both depression and sleeping problems, and some doctors also prescribe it for people with insomnia who do not have depression. 

Mirtazapine for Both Insomnia and Depression

Most of the research about mirtazapine’s effects on sleep come from studies in which the drug was used in people who had both sleeping problems and depression. Insomnia, which is defined as trouble falling or staying asleep, is common among people with mental health conditions like depression. 

In a handful of studies, mirtazapine was found to have beneficial effects on sleep, including an improvement in total time spent sleeping and better sleep quality. Mirtazapine may be helpful in both decreasing depressive symptoms and enhancing sleep. Some researchers believe that some of mirtazapine’s impact on depression may come from its ability to reduce sleeping problems .

One potential benefit of mirtazapine compared to many other antidepressants is that it does not restrict rapid eye movement (REM) sleep, which is believed to be important for thinking and memory. However, dreaming is most vivid in REM sleep, and there have been some reports of nightmares in people taking mirtazapine.

Mirtazapine for Insomnia

Expert groups generally do not recommend prescribing mirtazapine to treat insomnia in people who do not have depression. Despite this, some doctors will occasionally prescribe mirtazapine for people with insomnia alone.

Very little research exists to evaluate the sleep-related effects of mirtazapine in people without depression. In one small study, people who took mirtazapine slept longer and had fewer sleep disruptions. They showed increases in deep sleep without a reduction in REM sleep.

Although most people in research studies have found mirtazapine to be tolerable, it can cause side effects. Given the limited track record in treating insomnia in people without depression, the American Academy of Sleep Medicine does not include mirtazapine in its general recommendations of medications for treating insomnia

Mirtazapine Dosage for Sleep 

When prescribed for sleeping problems in people without depression, mirtazapine is usually given in a dose of 7.5 or 15 milligrams. Mirtazapine at these dosage levels tends to cause more drowsiness than higher doses of the drug. 

In most cases, mirtazapine is taken once a day before bedtime as a tablet that is either swallowed or that disintegrates inside the mouth. 

How Long Does Mirtazapine Take To Work?

For some people, the sleep-inducing effects of mirtazapine appear within one or two days after starting to take the drug. When used for depression, mirtazapine may take multiple weeks to have a noticeable effect.

Side Effects of Mirtazapine

Like most medications, mirtazapine can cause a wide range of side effects. One of the most common side effects is feeling tired or drowsy, which is actually an intended effect when the drug is used to address sleeping problems. Other side effects that were most frequently experienced across research studies with mirtazapine include: 

  • Dry mouth
  • Increased appetite
  • Weight gain
  • Dizziness 

Additional side effects that can occur when taking mirtazapine include: 

  • Confusion
  • Anxiousness
  • Constipation
  • Nausea and vomiting

Although uncommon, mirtazapine may lead to potentially serious side effects. Immediate medical assistance should be sought by anyone experiencing: 

  • Chest pain
  • Rapid heartbeat
  • Seizures
  • Fever, chills, or other flu-like symptoms

As with a number of antidepressants, the FDA warns that people under the age of 24 who take mirtazapine may be more likely to have thoughts of suicide. While this is uncommon, it should prompt immediate care from a doctor, mental health professional, or suicide prevention service. 

Some side effects may also arise when abruptly stopping mirtazapine. These withdrawal symptoms can include: 

  • Depression
  • Panic attacks
  • Insomnia
  • Gastrointestinal distress

For this reason, anyone planning to stop taking mirtazapine should consult with a doctor about how to gradually discontinue its use. 

Alternative Ways to Improve Your Sleep

Sleep medications are not the only way to address insomnia. If you experience difficulty falling or staying asleep, improving your sleep hygiene may help. 

Sleep hygiene includes the habits and environmental factors that can influence your sleep at night. A series of small changes in your lifestyle and environment may have noticeable impacts on your quality of sleep.

People who are looking for additional support in making lifestyle changes to improve their sleep may want to consider talking with a health care provider about cognitive behavioral therapy for insomnia (CBT-I).

“While CBT-I is the recommended first-line therapy for insomnia, it is often hard to find qualified professionals who deliver this therapy. Medications can help in the short term.”

Dr. Abhinav Singh, Sleep Physician

Changes to Your Daily Routine

Changes in your daily routine can help you regularly get good sleep at night. While it might be difficult to immediately overhaul your routines, try small steps to incorporate certain changes into your day: 

  • Make time for exercise or other physical activity 
  • Follow a consistent schedule for going to bed and waking up 
  • Aim to be outside for at least 30 minutes of natural sunlight exposure 
  • Avoid naps that are long or too late in the day 
  • Stop drinking caffeine by early afternoon at the latest 

Tips Before Going to Bed

One part of sleep hygiene is preparing your mind and body for sleep. Practical tips before going to bed include: 

  • Avoiding electronics and screens for an hour or more before bedtime 
  • Establishing a consistent and relaxing bedtime routine 
  • Limiting alcohol and heavy foods later in the evening 

Creating an Environment Conducive to Sleep

Your bedroom environment can affect how well you sleep. Some ways to enhance your sleep setting include: 

  • Keeping the lights off 
  • Removing electronics and other distractions from the bedroom 
  • Keeping your bedroom comfortably cool 

Talk With Your Doctor

If sleep hygiene improvements are not bringing about better sleep, talk with your doctor about the most appropriate next steps. Your doctor can discuss your sleep habits and the pros and cons of various treatments for insomnia and other sleeping problems. 

Medical Disclaimer: The content on this page should not be taken as medical advice or used as a recommendation for any specific treatment or medication. Always consult your doctor before taking a new medication or changing your current treatment.

If you or someone you know is in crisis, dial 988 to reach the Suicide and Crisis Lifeline, which provides 24/7, free, and confidential support.

Learn more about our Editorial Team

5 Sources

  1. Jilani, T. E., Gibbons, J. R., Faizy, R. M., & Saadabadi, A. (2022, September 7). Mirtazapine. In StatPearls. StatPearls Publishing., Retrieved April 12, 2023, from

  2. Alam, A., Voronovich, Z., & Carley, J. A. (2013). A review of therapeutic uses of mirtazapine in psychiatric and medical conditions. The Primary Care Companion for CNS Disorders, 15(5), PCC.13r01525.

  3. Gandotra, K., Chen, P., Jaskiw, G. E., Konicki, P. E., & Strohl, K. P. (2018). Effective treatment of insomnia with mirtazapine attenuates concomitant suicidal ideation. Journal of Clinical Sleep Medicine, 14(5), 901–902.

  4. Neubauer, D. N. (2023, April, 5). Pharmacotherapy for insomnia in adults. In R. Benca, & J. G. Elmore (Eds.). UpToDate., Retrieved April 12, 2023, from

  5. 988 Suicide and Crisis Lifeline. (n.d.). Substance Abuse and Mental Health Services Administration., Retrieved April 12, 2023, from


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