Why Do We Dream

Whether bizarre and fantastical events or ordinary, trivial matters, they all appear in our dreams. Some dreams are so vivid that we remember them clearly after waking, while others vanish instantly without a trace. What is happening behind this? What controls these experiences? Why do humans dream?

Our sleep repeatedly passes through multiple stages, and in different stages, our bodies undergo different changes. Sleep can mainly be divided into two phases: non‑rapid eye movement sleep (NREM sleep) and rapid eye movement sleep (REM sleep). Within NREM sleep, there are three stages: the falling‑asleep stage, light sleep, and deep sleep. We first enter the falling‑asleep stage, then light sleep, and finally deep sleep. In deep sleep, our heart rate, body temperature, and breathing gradually slow down, it becomes difficult to wake us, and the body secretes growth hormones. The body is repaired, and energy gradually restored. After this, we enter REM sleep. In REM sleep, the eyes move rapidly, heart rate and breathing increase, and brain activity accelerates. Dreams are easily generated in the brain, and most of our dreams occur during REM sleep.

Humans have not yet fully understood the reasons and mechanisms of dreaming. In ancient times, many believed that during sleep, the soul, or part of it, left the body, and the things seen in dreams were experiences encountered by the soul outside the body. Some ancient civilizations believed dreams were a kind of prophecy, a revelation from the gods. In modern science, however, scientists generally believe dreams are activities of the human brain, a way for the brain to process memory, emotions, stress, and the unconscious. Dreams are a window for expressing desires and feelings from reality.

In the school of the famous Austrian psychologist and psychoanalyst Sigmund Freud, dreams are mainly driven by the unconscious and are “wish fulfillment.” He called dreams the “royal road to the unconscious,” a way to express desires repressed in daily life. But these desires do not appear directly in our dreams; they are disguised and distorted, presented indirectly. Moreover, dreams are not only wish fulfillment but can also reflect inner unease and fear. Dreams can be divided into manifest dreams and latent dreams. Manifest dreams are the surface form, the disguised and distorted version just mentioned. Latent dreams are the true, deeper meaning hidden beneath the manifest dream. For example, if you dream of running happily across a vast meadow, that is the manifest dream. The latent meaning beneath it may be that your current life and work are heavily constrained and stressful, leaving you breathless, so the dream expresses this in a disguised form. Of course, this is just a simple example.

One school of neuroscience theory holds that dreams are merely products of the brain’s processing of information and memory. Scientists who support this view disagree with Freud. They believe dreams are products of brain activity during REM sleep. The images in dreams are simply the presentation of various signals received by the brain during REM sleep, organized together. These images are random, mixed, and illogical, yet our brains integrate them and assign meaning.

So, is dreaming actually good or bad? Does frequent dreaming harm the body? In fact, dreaming is a very normal physiological phenomenon. Humans generally have three to six dreams each night. Dreaming usually does not affect sleep. If someone says they rarely dream, in many cases it is simply because they do not remember the content of their dreams. Usually, only particularly strange dreams, or dreams interrupted by waking at the time, are remembered clearly. Otherwise, in many cases our brains do not retain dream content, especially those very ordinary dreams.