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Why do we have dreams and nightmares?

Why do we have dreams and nightmares?

Dreams are a fascinating and mysterious world. Everyone wondered at least once about the meaning of their dreams. From recurring, to vivid and premonitory dreams, this area always had the ability to catch our interest.

Even though we don't always remember them, every time we sleep in the REM phase we have dreams.

But why do we dream?

The truth is that there's more than one answer to this question. There are many theories that can explain why we dream, and they're all likely:

  • We dream to forget: there are more than 10,000 trillions neural connections inside our brain, created by things we think and do. According to a 1983 neurobiological theory, while we sleep the neocortex reviews these connections and it deletes the unnecessary ones, and this process gives life to dreams.
  • We dream to rehearsal: another theory says that dreams that contain danger (like fighting an attack or running from an aggressor) are a way to practice our fight or flight response, so that we're prepared in case we need it in real life.
  • We dream to remember: according to many studies, when we sleep we collect memories. In these studies, it was highlighted that sleep helps maintain the information acquired during the day. For this reason, if you have an exam is recommended to study and then go to sleep (and not to pull an all-nighter!) to retain the information learned.
  • We dream to heal: stress neurotransmitters are less active during sleep and many researchers theorize that dreams can be a way to deal with traumatic situation and negative emotions so that we can feel better psychologically.
  • We dream to keep our brain active: the brain needs to stay active during sleep out of necessity. According to the Continual Activation Theory, dreams would be a way to keep the brain active when exterior input are low. Basically, dreams are a sort of "screen saver".

And why do we have nightmares?

On the other side, there are nightmares, those dreams that scare us and make us upset. As for normal dreams, there are a few theories to explain them:

  • Stress and worry: high levels of stress have been linked to a higher level of nightmares. Disorders like depression and anxiety are also linked to them.
  • To face a traumatic event: as we explained before, dreams could be a way to process traumatic events. For this reason, people who suffer from PTSD (post-traumatic stress disorder) generally have many nightmares, especially regarding the event. It's a way for the brain to process what happened.
  • Alcohol and drugs: many studies demonstrated that a high consumption of alcohol and drugs can cause nightmares. Moreover, there are a few legal drugs that can cause them as well.
  • Eating a lot before bed: heavy meals before sleeping can make our brain very active during sleep, provoking nightmares.