Nightmares: what they mean and how to have fewer

Nightmares versus bad dreams

Not every unpleasant dream is a nightmare. Sleep researchers usually call it a nightmare when the fear, dread or disgust is strong enough to wake you, and you remember the dream clearly. A bad dream is upsetting but you sleep through it, and it may only come back to you later in the day. Both come mostly from REM sleep, which is why they cluster in the early morning hours, when REM periods are longest.

Nightmares are also different from night terrors. A night terror happens in deep non-REM sleep, usually early in the night; the person may scream, thrash or sit up looking terrified, but is hard to wake and remembers little or nothing. Night terrors are most common in children. With a nightmare, you wake fully and the dream is fresh in your mind.

Why do I keep having nightmares?

A run of nightmares almost always has a reason. These are the most common.

• ✦Stress and anxiety: worries at work, at home, about money or health are the most common cause of all.
• ✦A frightening or painful experience: after an accident, an assault, a loss or other trauma, nightmares that replay or echo it are common.
• ✦Not enough sleep or an irregular schedule, which can bring REM rebound and more intense dreams.
• ✦Alcohol: it may help you fall asleep, but as it wears off later in the night, sleep becomes lighter and dreams more intense.
• ✦Some medicines, or stopping them, can bring on disturbing dreams.
• ✦Illness and fever, which produce their own strange, frightening fever dreams.
• ✦Scary films, books or news close to bedtime, which give the mind fresh material.

Bad dreams meaning: what your nightmare is about

Most theories agree that nightmares are the mind working on fear. Antti Revonsuo's threat simulation theory proposes that frightening dreams evolved as a rehearsal for danger, letting us practice escape and defense in safety. Others see bad dreams as the brain trying, and sometimes failing, to process strong emotions overnight. In both views, a nightmare is not a random horror. It takes something you are afraid of and puts it on stage.

So the most useful question is not "what does this monster mean?" but "what in my life feels like this?" The pursuer in a chase dream may be a conversation you are avoiding. A house on fire may be a home life under strain. A demon or faceless figure often gives shape to guilt, shame or a fear you cannot name. Look at the feeling and the situation in the dream, and you will usually find its twin in your waking life.

How to stop nightmares

You cannot switch nightmares off, but you can make them less frequent and less frightening. These steps help most people.

1. 1.Keep regular sleep and wake times, even at weekends. A stable rhythm calms REM sleep.
2. 2.Cut down on alcohol in the evening, and avoid heavy meals right before bed.
3. 3.Wind down for an hour before sleep, without frightening shows, news or work email.
4. 4.Write down worries before bed, with one small next step for each, so your mind can set them down.
5. 5.If you wake from a nightmare, get your bearings: sit up, turn on a soft light, notice the room, and breathe slowly until your heart settles.
6. 6.Write the nightmare down in daylight. Seeing it on paper often makes it smaller, and patterns become clear.

Rewrite the ending: imagery rehearsal

One of the best-studied approaches for repeated nightmares is imagery rehearsal therapy. The idea is simple: while awake, you write down a nightmare, change its story in any way you like, and then spend a few minutes each day picturing the new version. The new ending does not have to be heroic. The pursuer can turn out to be a friend, the door can open, the water can go calm.

Clinicians use it as a structured treatment, especially for nightmares after trauma, but the basic exercise is gentle enough to try on your own for an ordinary recurring bad dream. If a nightmare is tied to a traumatic memory, it is better done with a therapist. Some people also learn to become lucid in nightmares, so they can remember it is a dream and change it from inside; our guide to lucid dreaming explains how.

Nightmares after a frightening experience

After an accident, an assault, a sudden loss or any event that overwhelmed you, nightmares that replay it, or echo it in disguise, are very common. They are a sign that the mind is still trying to file something too big to file. They often fade as weeks pass. When they do not, or when they come with flashbacks, jumpiness or avoiding reminders of what happened, trauma-focused therapy helps many people, and nightmares often ease along with everything else. Be gentle with yourself in the meantime: a nightmare like this is not weakness and not a bad omen, it is an injury still healing.

Nightmares in children

Nightmares are common in children, especially in the preschool and early school years, as their imagination grows faster than their ability to tell fantasy from reality. Comfort them, keep the room calm, and talk about the dream in daylight if they want to. Drawing the nightmare and then drawing a new ending is a child-sized version of imagery rehearsal. Frequent nightmares that upset a child's sleep or days are worth mentioning to their doctor.

When to talk to a doctor

If nightmares come often, make you afraid to go to sleep, or leave you tired and on edge during the day, they are worth raising with a doctor. Frequent nightmares are recognized as a sleep problem in their own right and are treatable.

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