Dreams and Nightmares

Patient Information Brochure


What is dreaming?

Dreaming is a form of mental activity that occurs during sleep. Dreaming can vary from very simple thoughts or images to elaborate stories with vivid colour images, sounds and intense physical activity.

Dreaming takes place throughout a night of sleep. While it was believed for many years that dreaming occurred only during rapid eye movement (REM) sleep (the stage of sleep that occurs every 90 minutes and is characterized by rapid eye movements, intense brain activity and muscle paralysis), we know now that dreaming of varying degrees of intensity and vividness can be experienced during all stages of sleep. For example, short vivid dreams can occur at the onset of sleep, thought-like dreams can occur during non-REM sleep and more detailed, active and emotional dreams typically occur during REM sleep, particularly in the latter part of a night’s sleep.

Dream recall

Many people do not remember their dreams. However, research in the laboratory has demonstrated that almost everybody experiences dreaming sometimes (e.g., when awakened from REM sleep) but, for a number of reasons (e.g., short sleep, lack of interest, distraction by radio-alarm clock), people may not recall their dreams when waking up at home. Dream recall can be improved by some simple measures such as changing wake-up times, paying attention to dreams immediately upon awakening and writing them down, or telling them to a spouse or friend. Simply developing an interest in dreams and a motivation to remember them has been found to increase dream recall. It is well documented that women have a greater interest in dreams than men and remember them more often.

What are the sources of dreams?

How dreams are generated is still a debate among sleep and dream researchers. Typically, dreams have been found to incorporate, in one form or another, events that occurred during the previous day, although events from about a week ago are also regularly incorporated. Research has also demonstrated that in elderly persons, dream elements can refer to events dating back 50 to 60 years. Differences in age, gender, cultures and social role have been found to be reflected in dreams. For example, laboratory dreams of young children contain more animals than human beings. Also, women have more verbal interactions in their dreams than do men who tend to have more anxiety and physical aggression.

Dreams appear to be in continuity with many aspects of waking life. However, some common daytime activities, like reading, writing, or counting, rarely appear in dreams. Also, representations of waking experience in dreams are often distorted such that often only the dreamer can understand the links. Many dreams are also unpleasant for the dreamer, a fact that usually contrasts with a person’s waking life.

Are dreams useful?

Dreams are a natural phenomenon and there is no harm in recalling them. In fact, the distorted representations that dreams express can be useful when they provide creative images and associations. Many artists and writers use dream images and stories to inspire them in their work. Scientific discoveries have also arisen from dreams. However, since many dreams are unpleasant, they can sometimes negatively affect mood at wake-up and later on into the day.

Because dreams can reflect a person’s waking state of mind or concerns, they are often used in psychotherapy. There are also many techniques of working with dreams that have been developed to help people gain insight, solve problems or improve relationships in everyday life. Although paying attention to dreams can help improve self-awareness, universal dream symbols found in popular books are the result of unscientific speculations.

Nightmares and sleep terrors

Some dream experiences are particularly distressing and have a negative impact on waking life. Nightmares are well-elaborated dreams that have a frightful, anxious or other dysphoric content that usually wakes up the dreamer. Nightmares tend to occur late in the night and normally during episodes of REM sleep.

Sleep terrors, in contrast, are characterized by sudden awakenings from deep (nonREM) sleep near the beginning of the night. Although they, too, are associated with intense and negative mental experiences, these are typically very short and not remembered the next morning. The person wakes up from a sleep terror very suddenly with dramatically increased respiration and heart rate and outward expressions of fear or panic. Sleep terrors can cause serious injuries at night and substantial daytime distress.

Nightmares increase in prevalence through childhood into adolescence. From 1% to 4% of parents report their preschoolers have nightmares “often” or “always”. Nightmare prevalence increases from ages 10 to 13 for both males and females but continues to increase to ages 20-29 for females, when it can be twice as high as for males. From then, nightmares decrease in prevalence with age but the gender difference remains. Among adults, prevalence of nightmares at least monthly is 6%, for frequent nightmares (i.e., 1/week or more) it is 1%-2%. Frequent nightmares can have a detrimental impact on daytime functioning. When nightmares do not disappear spontaneously, psychotherapy may help. Research has demonstrated that simple techniques of dream narration and transformation of the storyline are very useful in eliminating nightmares. Children may be encouraged to share their nightmare experiences with parents and professionals; very young children can benefit from drawing them.

It is well documented that traumatic experiences can trigger intensive recurrent nightmares. These nightmares can be associated with post-traumatic stress disorder (PTSD), which is often experienced as a result of war, assault, accidents, and other trauma. Professional help is recommended to alleviate recurring nightmares following trauma.


Authored by:
Joseph De Koninck, Ph.D., FRSC
Emeritus Professor of Psychology
University of Ottawa
Tore Nielsen, Ph.D.
Professor of Psychiatry
Université de Montreal