Writer: Srilalitha Jyosyula
Dreams are the strangest yet most vivid experiences we can have and they happen every single night! In fact, people spend about two hours dreaming every night, even if they don’t remember what they have dreamed [3]. During those two hours, our brains create a series of images, sounds, and sensations that can feel as real as our waking experiences.
This has been a fascination for a large part of human history: from ancient Mesopotamian dream diaries to published scientific studies in the modern day [3]. But even after thousands of years, there is no overarching reason for why we dream. Scientists have offered many theories but there is no definitive answer [1].
Some of the uncertainty comes from the intangibility of dreams. For much of history, dream research relied on people’s own reports of what they saw in their dreams. It wasn’t until MRI scans to image the brain were developed that researchers could understand the anatomical basis for dreams. They found that when we dream, we have increased activity in the parts of our brains that are responsible for movement (such as running, falling, or talking) and sensory input when we’re awake [1]! On the other hand, brain areas linked to logic and self-awareness had little to no activity at all. That’s why we sometimes dream of completely nonsensical things like a dog teaching algebra or your house falling into a pit of lava.
Most people dream about four to six times a night but only remember them if they wake up during or immediately after REM sleep [2], [4]. Otherwise, the memory fades almost instantly. Individual people can have wildly different levels of dream recall: some people can remember every little detail while others don’t remember dreaming in the first place.
It’s not just humans that dream! Animals also experience REM sleep and have twitching paws or tails, which may be a clue that they can also dream [3].
As for the purpose of dreaming, some scientists think that dreams are a by-product of REM sleep, the stage of sleep marked by high levels of brain activity that almost mirror waking brain activity [3], [2], [4]. However, it seems that REM sleep and dreaming are somewhat independent because it is possible to have REM without dreaming or vice versa depending on which area of the brain is damaged [4].
Another leading theory is that dreaming helps with memory and learning. During sleep, the brain could be sorting through the events of your day, strengthening useful connections and removing unnecessary ones [3], [4]. Dreams could also be some sort of practice for real-life situations, such as processing emotions, solving problems, or preparing for future problems [4].
Basically, while you dream of flying through the skies, your brain might be quietly reorganizing your brain, solidifying your memories and preparing you for waking life. We may never understand dreams, but they are a reminder that even while we sleep our brains are busy learning and understanding the world around us.
References
1. MacDonald J. Nobody really knows why we dream. JSTOR Daily. October 15, 2019. Accessed October 26, 2025. https://daily.jstor.org/nobody-really-knows-why-we-dream/
2. Marks H, Booth S. Dreams. WebMD. Accessed October 26, 2025. https://www.webmd.com/sleep-disorders/dreaming-overview
3. What is a dream and why do we have them? BBC Bitesize. Accessed October 26, 2025. https://www.bbc.co.uk/bitesize/articles/zmnjb7h
4. Why do we dream? Cleveland Clinic. Accessed October 26, 2025. https://health.clevelandclinic.org/why-do-we-dream
5. Zhang J, Pena A, Delano N, et al. Evidence of an active role of dreaming in emotional memory processing shows that we dream to forget. Sci Rep. 2024;14:8722. doi:10.1038/s41598-024-58170-z