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What Are Nightmares & How Do They Occur?

Nightmares are universal human experiences that span across cultures and ages. They are frightening dreams that can arouse people from sleep and leave them with unpleasant emotions, such as fear, guilt or anxiety. People experiencing nightmares may awaken with a pounding heart or rapid breathing. Scientists have a difficult time pinpointing exactly how nightmares and dreams occur since they cannot be directly observed. Certain physiological and psychological factors, however, are associated with the occurrence of nightmares.

  1. Nightmare Content

    • According to "Working with Dreams" by Ruth Berry, while the content of nightmares differs among individuals, certain types of nightmares are more common than others. Many people are familiar with nightmares in which they are being pursued or chased by another person or creature. People may dream that they are suffocating, being strangled or are paralyzed and cannot escape from a situation. In a nightmare, a person can witness or experience violence. Other common nightmares involve people struggling with exams or tests or failing to arrive at certain destinations.

    REM Sleep

    • In "The Corsini Encyclopedia of Psychology and Behavioral Science," edited by W. Edward Craighead and Charles B. Nemeroff, sleep is divided into two major phases: rapid eye movement (REM) sleep and nonrapid eye movement (NREM) sleep. REM sleep is the phase in which most people dream, and nightmares occur almost exclusively in this stage. In REM sleep, the brain is in an activated state, and brain metabolism is normal or slightly increased. During this time, the brain processes daily experiences and emotions. Brain activity may relate to nightmare activity, since in NREM sleep, which includes the deepest state of sleep, brain waves are slower, and brain metabolism is decreased. Brain stem neurons immobilize skeletal muscles during REM sleep. Sleepers who are falling asleep or awakening may become slightly conscious of their body's paralysis in REM sleep and have paralysis-related nightmares or hallucinations.

    Nightmare Triggers

    • According to Ruth Berry, Sigmund Freud believed that dreams were manifestations of repressed desires and that dreams appeared in symbolic form to mask these desires. Berry notes that modern psychologists tend to not agree with Freud's symbolic theory and alternatively perceive dream imagery as the natural picture language of sleep. People experiencing intense emotional periods in their waking life may have their sleep disrupted by stress and anxiety and may experience nightmares or insomnia. Illness, especially high fever, is linked to nightmares. People withdrawing from sleeping pills, alcohol or drugs may experience frightening dreams. Eating a large meal before sleep may also disrupt your sleep patterns because your body has to actively digest the food while you sleep.

    Nightmares and Night Terrors

    • Nightmares differ from another sleep phenomenon called night terrors. In "The Corsini Encyclopedia of Psychology and Behavioral Science," night terrors relate to waking up severely distressed, scared and disoriented. Nightmares contain elaborate imagery and generally occur during the last hours of sleep in the REM phase and are easier to recall. Night terrors occur during the first hours of sleep in the NREM phase and are harder to recall upon waking. Young children are more likely to experience night terrors than adults, and it is difficult to awaken a child who is having a night terror.

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