The Science Behind Why We Dream

Scientists have long pondered the meaning of dreams, and now in the 21st century, we have a clearer idea than ever of the scientific reasons behind why we dream.


Did you know that some of the world's most groundbreaking discoveries came to scientists, inventors, and artists in dreams? For example, Dr. James Watson, the founder of modern genetics, saw a spiral staircase in a dream in 1953. This inspired him to think of the structure of DNA as a double helix, and he went on to win the Nobel Prize in Physiology or Medicine in 1962. And nineteenth-century German chemist August Kekulé discovered the structure of a benzene ring (a chemical compound with six carbons arranged in a hexagonal ring) after dreaming of a snake chasing its own tail.

Scientists have long pondered the meaning of dreams, and now in the 21st century, we have a clearer idea than ever of the scientific reasons behind why we dream. However, it's critical to note that scientists are still studying this topic, and we don't have definite answers, but we do have some very solid theories. So let's get into them.

Connecting Experiences, Emotions, and Memories

Several recent studies have further increased our knowledge of exactly how dreams work and their role in our daily lives. For example, research published in the Journal of Neuroscience gave insight into how we remember our dreams.

Researchers invited 65 students to spend two nights in their research lab and measured their brain waves while they slept. The students we woken at different points in the sleep stages and asked to detail whether they dreamt or not and what they dreamt about. The researchers found that the students were most likely to remember their dreams when woken directly after REM sleep (the stage where you're most likely to have vivid dreams). Scientists connected this phenomenon to the low-frequency theta waves in the brain's frontal lobes. And interestingly, these low-frequency waves are the same mechanism that helps us construct and retrieve memories when we're awake.

Other studies have linked bizarre and emotionally intense dreams to activity in the amygdala and hippocampus - areas of the brain critical for processing emotion and memory.

Based on these studies, scientists theorize that we dream so we can process complex emotions in daily life. Our ability to process complex emotions is directly related to our social functioning and mental health. For example, scientists have also found a correlation between people who can't experience REM sleep due to injury or disease and mental disorders.

The Threat Simulation Theory (TST)

TST argues that dreaming developed as an evolutionary biological defense mechanism to help us prepare for threatening encounters. Essentially, we rehearse threatening events in our dreams so the same areas of our brain will be activated more quickly during wakefulness, should we ever find ourselves in a dangerous situation. Studies have found that traumatized people typically have more dreams and these dreams have a higher number of threatening events, lending some support to this theory.

The Activation-Synthesis Hypothesis

This theory sparked significant controversy when it was proposed by J. Allan Hobson and Robert McCarley in 1977. Essentially, this theory states that dreams have no special meaning but are just our way to make sense of the random images we see while asleep. Proponents of this theory argue that the brain experiences fires of electrical impulses during sleep, pulling random images, emotions, and thoughts from our memories. These experiences don't have a coherent narrative, but we apply one after we wake up as natural storytellers. In simple words, dreams are meaningless, but we apply meaning to them after the fact.

This theory angered proponents of other theories who firmly believed there must be an evolutionary function behind dreaming.