Nightmares: why they happen and how to have fewer of them

What is a nightmare?

A nightmare is a long, deeply unpleasant dream that wakes you up. It usually revolves around a threat: someone is chasing you, you're under attack, you lose someone you love, or something terrible is about to happen. When you open your eyes you know right away where you are, and you remember much of what you dreamed. The fear, sadness or anger can linger for a while.

A nightmare isn't the same as a bad dream. A bad dream is unpleasant too, but it doesn't wake you. Nor is it the same as a night terror, which happens in deep sleep early in the night: the person screams or thrashes, is hard to wake, and usually remembers nothing in the morning.

Nightmares mostly come during REM sleep, the stage of the most vivid dreams, which grows longer toward morning. That's why they so often wake you in the small hours.

Why nightmares happen

Nightmares rarely have a single cause. What we do know is that certain situations make them more likely, and that an occasional nightmare is a normal part of sleep: it doesn't mean something is wrong with you, and it doesn't foretell anything.

• Stress and anxiety: a stretch of deadlines, exams, a move or conflict at home tends to fill the night with restless dreams.
• Hard or traumatic experiences: an accident, an assault or a loss can come back again and again as nightmares.
• Too little sleep or odd hours: sleep loss and irregular schedules disturb REM sleep.
• Some medications, such as certain antidepressants or blood pressure drugs, and also stopping some medications abruptly.
• Alcohol and other substances, especially in excess or when someone quits suddenly.
• Fever and some illnesses, which can bring very strange dreams.

When nightmares become a disorder

Nightmare disorder is a recognized condition in sleep medicine. According to the American Academy of Sleep Medicine (AASM), it affects about 4% of adults. It isn't defined by an exact number of nightmares but by what they do to you: distressing dreams that keep coming back, break up your sleep and spill into your days.

Signs include waking in fear several times a week, dreading bedtime, staying up late to avoid dreaming, or feeling worn out, irritable and unfocused because of those nights. If that sounds familiar, it's worth bringing up with a doctor: there are treatments that work.

What to do tonight, when a nightmare wakes you

Waking from a nightmare leaves your body on high alert. These steps help bring the intensity down so you can get back to sleep, or at least rest.

• Remind yourself where you are. Quietly name three things you can see or touch: the sheet, the lamp, the wall. It tells your mind the danger was a dream.
• Breathe slowly: in for a count of four, out for a count of six, several times. A longer exhale tends to slow your heart.
• Turn on a soft light if the dark bothers you. You don't have to lie in the dark to prove anything.
• If the dream keeps circling, jot it down in a few lines and close the notebook. Getting it out of your head can take some of the weight off.
• If twenty minutes or so go by and you're still awake, get up for a bit, drink some water and do something calm in low light. Go back to bed when you feel sleepy.
• Skip your phone and any upsetting news: your mind is already on alert and doesn't need more.

Habits that help you have fewer nightmares

No habit gets rid of nightmares on its own, but looking after your sleep tends to make them less frequent. Go to bed and get up at about the same times, weekends included. Go easy on alcohol at night: it may make you drowsy at first, but it disrupts sleep in the early morning. Save horror movies and hard news for earlier in the day, and give yourself a calm stretch before bed, even ten minutes of reading or quiet music.

If a new medication lines up with the start of your nightmares, tell the person who prescribed it. Don't stop taking it on your own.

Imagery rehearsal therapy

Imagery rehearsal therapy, or IRT, is the psychological treatment with the strongest backing for frequent nightmares. The idea is simple: while awake, you pick a nightmare, change the story however you like, and rehearse the new version in your mind during the day. Over time, the original dream tends to lose its grip.

One of its leading researchers was the American physician Barry Krakow. In 2001 he and his team published a trial in JAMA with 168 women, survivors of sexual assault who had chronic nightmares and posttraumatic stress disorder. Those who received the therapy had fewer nightmares, slept better and saw their PTSD symptoms ease.

In 2018 the AASM published a position paper on treating nightmare disorder in adults. IRT is the only option it gives its firmest recommendation, both for nightmares tied to PTSD and for nightmare disorder. Other approaches, such as cognitive behavioral therapy, muscle relaxation and lucid dreaming therapy, are listed as options that may be used.

Imagery rehearsal, step by step

IRT is usually learned in a few sessions with a professional, and many people keep practicing it on their own. If your nightmares don't stem from trauma, you can try this simple version. If they come from something that really happened to you, do it with a therapist's guidance.

• Pick a nightmare that keeps coming back, and start with one that isn't the worst.
• Write it down during the day, at a quiet moment, without dwelling on the most upsetting details.
• Change it any way you want. You can alter the ending, the place, the characters or a single detail: the door that wouldn't open now swings open, the chaser stops, someone shows up to help. It doesn't have to make sense.
• Write out the new version in full, from start to finish.
• Rehearse it in your imagination for ten to twenty minutes a day, eyes closed, using every sense you can: what you see, hear and feel.
• Keep at it for several weeks. Once that nightmare loses its force, you can work on another.

Nightmares after trauma

Nightmares are very common after trauma. In posttraumatic stress disorder they are among the most frequent symptoms: according to the AASM, up to 80% of people with PTSD report them. Sometimes the dream replays what happened almost exactly; other times it dresses it up in other images but leaves the same sense of danger.

If your nightmares started after something that shook you, you don't have to face them alone. A psychologist or psychiatrist with trauma experience can offer specific therapies, IRT among them, and a doctor can consider whether a medication might help. Asking for help isn't overreacting: months of sleeping in fear wear you down, and it can get better.

In the dictionary you'll find several dreams of this kind, such as dreaming of war, a kidnapping or a mugging. They offer possible readings, but when a dream like that comes from something that really happened, the most useful thing isn't to interpret it but to take care of yourself.

When to get professional help

An occasional nightmare doesn't need treatment. It's a good idea to see a doctor or a psychologist if:

• You have nightmares more than once a week for several weeks.
• You're afraid to fall asleep or do everything you can to avoid it.
• The exhaustion or distress from those nights affects your work, school or relationships.
• The nightmares began after a trauma or replay something that happened to you.
• They showed up when you started a new medication.
• You also shout, move a lot or hurt yourself while asleep.