Nightmares are bad dreams that wake you up and that you can remember. The NHS says they affect both children and adults. In adults, the HSE says causes include stress, trauma and mental health conditions such as post-traumatic stress disorder (PTSD). Some medicines, such as antidepressants, can also cause them.
The NHS adds being very tired or unwell, and something that has frightened or worried you. Sleep conditions such as sleep apnoea, some brain conditions, and alcohol withdrawal can also play a part.
For most people, nightmares get better on their own. The HSE and NHS advise seeing a GP if you have regular nightmares that affect your sleep and your day-to-day life. Effective talking treatments exist.
Get help now
Call 112 or 999 in Ireland, 999 in the UK or 911 in the US, or go to an emergency department, if:
Contact your doctor straight away (or NHS 111 in the UK) if you take montelukast, an asthma and allergy medicine, and get new or worse sleep problems such as nightmares, mood changes or hallucinations.
See your GP if regular nightmares are affecting your sleep and daily life.
If you are having thoughts of suicide: in Ireland, freephone Samaritans on 116 123 or text 50808. In the UK, call Samaritans on 116 123. In the US, call or text 988.
Not everything frightening at night is a nightmare. The difference matters, because the causes and the help are different.
Source: NHS. If you cannot move or speak as you wake up or fall asleep, the NHS says this may be sleep paralysis.
If you shout, punch or kick while dreaming, that is a different problem. Night terrors, sleepwalking and acting out dreams are covered in our guide to sleepwalking, night terrors and acting out dreams. This article covers nightmares only.
The HSE and NHS both list stress as a common cause. The NHS also lists anxiety, worry, and seeing something frightening, such as a scary film. Mental health conditions such as generalised anxiety disorder can play a part.
If nightmares carry on, or the stress is ongoing, it is worth talking to your GP.
The NHS lists being very tired or unwell as a common cause. It also says a severe injury can disturb sleep for 4 to 6 weeks afterwards.
Nightmares are one of the main symptoms of PTSD. The NHS describes "recurring dreams or nightmares" alongside flashbacks and intrusive thoughts. A 2019 expert review says nightmares after trauma may replay the event, or carry related feelings or content in a different form.
PTSD is treatable. NICE guideline NG116 recommends trauma-focused talking therapies, such as trauma-focused CBT and, for some people, EMDR (eye movement desensitisation and reprocessing). Our guide to what PTSD guidelines recommend explains the options.
The HSE and NHS name antidepressants as one type of medicine that can cause nightmares. Others include:
A 2019 expert review found that medicines acting on noradrenaline, serotonin or dopamine are linked with nightmares in some people. It also says that stopping medicines that suppress REM sleep (dream sleep) has been reported to cause nightmares.
If nightmares started after a new medicine, a dose change or stopping a medicine, tell your GP or pharmacist. Do not stop a prescribed medicine on your own.
Alcohol changes dream sleep. A review of research in people with alcohol dependence found that REM sleep is usually suppressed during drinking. During withdrawal, REM sleep often rebounds above normal levels.
Most nightmares come from REM sleep. This may be one reason some people report vivid dreams or nightmares when they cut down. Our guide to what a nightcap does to your night explains how alcohol affects sleep stages.
If you drink heavily every day, stopping suddenly can be dangerous. The NHS says withdrawal symptoms can include anxiety, difficulty sleeping, shaking, hallucinations, confusion and seizures. Get medical help before you stop. Severe withdrawal symptoms need emergency care.
The NHS lists conditions that affect sleep, such as restless legs syndrome and sleep apnoea, among causes of nightmares. Sleep apnoea means your breathing stops and starts while you sleep.
A 2019 expert review describes a link between disturbed breathing in sleep and nightmares. It says treating sleep apnoea improved nightmares in some studies. If you snore loudly or wake unrefreshed, see our guide to checking for sleep apnoea.
The NHS also lists brain conditions such as Parkinson's disease. If you also move, shout or lash out during dreams, mention this to your GP.
Doctors call it nightmare disorder when repeated nightmares cause real distress or affect daily life. The nightmares must not be better explained by a substance, medicine or another condition.
How common is it?
Nightmare disorder can follow trauma, or start with no clear trigger. Either way, it can be treated.
Your GP will want to understand the pattern. They may ask:
The NHS suggests keeping a sleep diary. Note how long you sleep, how long it takes to fall asleep, and how you feel the next day.
Many people will not need tests. The NHS says a GP who suspects sleep apnoea may refer you to a specialist sleep clinic. Our guide to sleep studies explains what happens.
The NHS says cognitive behavioural therapy (CBT) can help adults who have frequent nightmares. CBT may also help with anxiety or insomnia that drives nightmares.
Imagery rehearsal therapy (IRT) is a form of CBT aimed at nightmares. While awake, you rewrite the story of a recurring nightmare so that it is no longer frightening. You then rehearse the new version in your imagination a few times each day.
The AASM's 2018 position paper recommends IRT for both PTSD-related nightmares and nightmare disorder. It was the only treatment given its top rating. The World Sleep Society endorsed this paper in 2025. These are US and international bodies. We did not find NICE or HSE guidance on IRT specifically.
Ask your GP or therapist whether someone trained in IRT is available. If nightmares come with PTSD, trauma-focused therapy is the first step.
The AASM says several medicines "may be used" for nightmares, where evidence is less clear. These include prazosin, an alpha-blocker medicine.
The evidence for prazosin is mixed. A large 2018 trial in 304 US military veterans with PTSD found prazosin did no better than placebo for distressing dreams or sleep quality. A 2020 meta-analysis pooling 7 prazosin trials found it reduced nightmare frequency compared with control groups. The AASM advises against clonazepam and venlafaxine for nightmare disorder.
Any medicine for nightmares is a decision for you and your doctor.
The NHS suggests:
If drinking is part of the picture, talk to your GP about cutting down safely.
A 2019 expert review reported that recurrent nightmares are linked to a higher risk of suicide attempts. This held after allowing for depression and other factors. If nightmares come with low mood or thoughts of self-harm, please tell your GP.
Yes. The NHS says nightmares affect both children and adults. See a GP if they are regular and affecting your sleep or daily life.
During alcohol withdrawal, dream sleep often rebounds. That may make dreams more vivid. If you drink heavily, get medical advice before stopping, as withdrawal can be dangerous.
Yes. The HSE names antidepressants. The NHS lists nightmares as a side effect of propranolol and montelukast. Speak to your GP or pharmacist, and do not stop a medicine without advice.
Often not. A GP may refer you to a sleep clinic if they suspect sleep apnoea or another sleep disorder, such as acting out your dreams.
This article is general information, not medical advice. It cannot diagnose the cause of your nightmares. Talk to your GP about your own symptoms, and before starting, stopping or changing any medicine.
Reviewed by: Proco Team
Last updated: November 2026