Does Remeron Make You Tired? Morning Grogginess and What Helps
Sleepiness is the most common Remeron side effect, affecting more than half of people in the FDA trials.
By withClaro Editorial · 2026-11-02 · 4 min read
Clinical section reviewed by Dr. Jason Tan , Consultant Psychiatrist, on October 27, 2026.
Key takeaways In the FDA trials, sleepiness affected 54% of people on Remeron against 18% on placebo. About 1 in 10 stopped Remeron because of sleepiness in those trials. Remeron leaves the body slowly, so much of an evening dose is still there in the morning, which explains the grogginess; in women it lingers longer on average. On Reddit, 94 of 102 people who said whether Remeron made them more tired said it did. On this page
How tiredness on Remeron went for people on Reddit Why does Remeron make you so sleepy? Does Remeron tiredness go away? What should you tell your prescriber about tiredness on Remeron? Remeron (mirtazapine) often makes people tired. Sleepiness is its most common side effect: in the FDA trials it affected 54% of people on Remeron against 18% on placebo. The label recommends taking it in the evening, before sleep.
How tiredness on Remeron went for people on Reddit
Of 102 people on Reddit who said whether Remeron made them more tired, 94 said it did and 8 that it did not. We read 100 recent threads on r/antidepressants, r/Anxiety, r/insomnia and other subs, comments included, and 104 people described their own experience. These threads were chosen because they were about tiredness, so the numbers show what tiredness looks like when it happens, not how often, and some came from r/insomnia, where people take Remeron to sleep.
Only 28 of the 104 said how it went over time, a small group: 15 said the tiredness faded and 13 were still tired. One person on Reddit wrote:
It put me in a 13-hour deep sleep that I just couldn’t shake off.
For another it passed:
the fatigue has passed
Why does Remeron make you so sleepy?
Two things in the label explain it. Mirtazapine blocks histamine H1 receptors, the same target as sleepy allergy pills, and the label links this to its strong sleepiness. It also leaves the body slowly: its half-life is about 20 to 40 hours, and longer in women, 37 hours on average against 26 in men, so in women the morning heaviness tends to last longer. Much of an evening dose is still in the blood the next morning, and with daily doses levels build up over the first 5 days. That is why the morning after can feel heavier than the first night, and why grogginess can peak in the first week. Older adults clear it more slowly too, and the label warns that sedating drugs can cause confusion and over-sedation in them.
Does Remeron tiredness go away? Medically reviewed by Dr. Jason Tan on October 27, 2026, this section only.
The label says it is unclear whether people get used to the sleepiness, and in the trials 10.4% stopped Remeron because of it, against 2.2% on placebo. On Reddit, about half of the 28 who said how it went over time said it faded. The clinical view:
When it lasts, it can come from the medication, from depression itself or from poor sleep.
What can help:
taking the dose in the evening, if your medication allows it regular sleep, daylight and light activity, rather than extra caffeine not driving or using machinery if you feel drowsy Tell your prescriber if tiredness lasts beyond the first weeks or comes with low motivation and feeling flat. A lower dose or a different medication can help. ## Is it safe to drive on Remeron?
Not until you know how it affects you. The label asks you not to drive until you are reasonably sure Remeron doesn't affect your ability to, and to avoid alcohol and benzodiazepines, which add to the impairment. A small 2013 study gave 13 healthy men mirtazapine at night for 8 days and tested them in a driving simulator. Starting on 15 mg worsened lane-keeping, while 7.5 mg did not, though both made people feel sleepy; raising the dose from 7.5 to 15 mg after a week did not worsen driving. It was tiny and in healthy volunteers, so it suggests the start is the riskiest time, not which dose to ask for.
Some tiredness can't wait for the next visit. If you fall asleep at work or behind the wheel, can't wake properly, or your mood drops sharply or thoughts of self-harm appear in the first weeks, contact your prescriber right away. If you're having thoughts of harming yourself, contact emergency services or a crisis line straight away. In the US, call or text 988. In the UK, call Samaritans on 116 123. Elsewhere, find a crisis line near you .
What should you tell your prescriber about tiredness on Remeron?
Tell your prescriber how tired you are, when in the day it hits and how you sleep. Because the morning is often the worst part, note how long the heaviness lasts after you wake and whether it is easing over the weeks. It helps to tell them:
Your dose and what time you take it. How long you sleep and how you feel on waking. Whether the grogginess is easing or not. Other medicines that make you sleepy, including benzodiazepines. Whether driving or work has been affected. More on doses in Remeron dosage .
Download on the App Store Morning grogginess on Remeron can shift over the first weeks. The withClaro app lets you log sleep, energy and mood each day, linked to your dose, and turns it into a report for your prescriber.
Frequently asked questions Why does Remeron make me groggy in the morning? Because it leaves the body slowly, with a half-life of 20 to 40 hours, much of the evening dose is still active in the morning. Tell your prescriber how long the grogginess lasts each day.
Can I drink alcohol on Remeron? The label advises avoiding it: alcohol adds to Remeron's effect on thinking and movement, which makes the sleepiness worse. If you do drink, tell your prescriber how much and how often.
How long does Remeron take to wear off? Most of a dose is gone within about a week of the last one, so grogginess can linger for a few days. Don't stop on your own to get rid of it: the label recommends a gradual reduction rather than a sudden stop, planned with your prescriber.
Is Remeron prescribed for sleep? The label approves it for major depression in adults only. Prescribing it for sleep is off-label, which is legal and common, but ask your prescriber what they expect it to do for you.
Related articles
More about Remeron Same topic, other medications
Sources REMERON (mirtazapine) prescribing information, US Food and Drug Administration via DailyMed, revised November 2021 Iwamoto et al., 2013, Human Psychopharmacology: Effects of low-dose mirtazapine on driving performance in healthy volunteers Claro articles are for self-monitoring and educational purposes only. They are not a medical device, therapist, or diagnostic tool, and do not replace care from your prescribing clinician. If you are in crisis, contact your care team, emergency services, the Samaritans (UK: 116 123), or the Crisis Text Line (US: text HOME to 741741).