Home Mind & Brain Why Do We Have Nightmares?

Why Do We Have Nightmares?

Reading Time: 3 minutes

Few experiences are as jarring as waking up from a nightmare, heart pounding and sheets damp with sweat. Almost everyone has been rudely yanked from sleep by a distressing dream at some point. But what causes these night-time horrors, and why do our brains thrust us into imaginary worlds of fear and dread?

A brief foray into the nature of dreams

Before diving into the murkiness of nightmares, it’s useful to understand what dreams are in general. Dreams are sequences of thoughts, images, emotions, and sensations occurring in the mind during certain stages of sleep, particularly REM (rapid eye movement) sleep. They are the product of a complex interplay between neural pathways, with the brain sifting through and processing the vast quantities of information it receives each day.

The evolutionary angle

Some evolutionary psychologists posit that nightmares, like dreams, have an adaptive purpose. They might have evolved as a mechanism for our ancestors to rehearse possible future threats in a safe environment. This “threat rehearsal” theory suggests that experiencing and confronting fears in dreams better prepared early humans for real-world dangers.

Imagine our ancestral hunter waking from a dream where he was chased by a large predator. That nightmare, as distressing as it was, might have sharpened his reflexes or made him more cautious the next day – thus increasing his chances of survival.

Processing emotional experiences

Another school of thought focuses on the emotional aspect. Psychologists believe that dreams, including nightmares, are a way for the brain to process unresolved emotions, especially negative ones like fear, anxiety, anger, and sadness.

Consider a particularly stressful day, full of confrontations or disappointments. That night, the brain dives into these unresolved feelings, spinning a narrative that becomes a nightmare. It’s almost as if the mind is trying to confront and make sense of these emotional experiences, even if the resulting dreams are distressing.

Responses to traumatic events

Posttraumatic stress disorder (PTSD) and other trauma-related conditions frequently present with nightmares as a prominent symptom. Victims of trauma often relive their experiences in their dreams. This can be incredibly distressing and can lead to a cycle of anxiety and further sleep disturbances. The repeated exposure to traumatic events in dreams might be the brain’s attempt to process and come to terms with the trauma, though, often, this process can feel agonisingly slow and painful for the sufferer.

Influence of medications and substances

Certain medications and substances can increase the likelihood of experiencing nightmares. For instance, some antidepressants, blood pressure medications, and drugs used to treat Parkinson’s disease can lead to vivid and distressing dreams. Furthermore, substance withdrawal, especially from alcohol or recreational drugs, can also lead to an increase in nightmares.

The mystery continues

While these theories provide a fascinating insight into the possible reasons behind nightmares, the exact cause and purpose remain elusive. Our understanding of the human brain is still in its infancy, and dreams, being an intricate part of our cognition, remain one of its most enigmatic phenomena.

Coping with nightmares

Although occasional nightmares are normal, recurrent nightmares can be disruptive to one’s quality of life. For those who struggle with frequent nightmares:

  • Establish a routine. Regular sleep patterns can help stabilise the body’s internal clock, potentially reducing the chances of nightmares.
  • Create a relaxing bedtime ritual. Activities like reading a light book or listening to soothing music can ease the transition to sleep.
  • Limit stimulants. Reduce the intake of caffeine and sugar before bedtime.
  • Seek professional help. If nightmares are persistent and causing distress, it might be beneficial to consult with a sleep specialist or therapist to uncover any underlying causes.


While nightmares can be unsettling, understanding that they might be the brain’s way of processing emotions, rehearsing for potential threats, or responding to various stimuli can provide some comfort. However, as science delves deeper into the realms of the mind, there’s hope that we’ll uncover even more about the mysteries of our night-time tales of dread.

Colleen Morningside is a freelance writer hailing from Bozeman, Montana, with a penchant for decoding the human mind’s enigmas.

© Copyright 2014–2034 Psychreg Ltd