Why do we dream? Discover the surprising benefits of our dreams
Why do we have dreams at night? Lottie Storey looks at the science of sleep and the nightly stories we enact there.
“Dreams are toys,” declared Antigonus in The Winter’s Tale, and anyone who’s experienced the surreal, fantastic or downright bonkers places our dreams can take us would agree with this. There is a playful nature to our dreams, sure, but what actually happens behind closed lids? Why do we dream in the first place?
Nobody knows for sure. We do know what happens in our brains when we sleep, though. Four stages of sleep produce four different levels of electrical activity in the brain, predominantly in the right half. Falling asleep takes us rapidly through from level 1 to 4 and we surface and descend through these stages throughout the night.
Another stage of sleep exists in which our eyes move rapidly back and forth, giving this cycle its name: rapid eye movement or REM sleep. It’s during this stage that people usually report having dreamed – physical rest and neurological activity coexist here, curiously. The electrical activity measured in the brain during this dreaming state of sleep is identical to when we are awake, which is why it’s also called paradoxical sleep. And it’s also where we go when we are hypnotised. The other four sleep stages allow us to toss and turn but during REM sleep our muscles become paralysed, preventing us from acting out our dreams.
Across an average night, humans spend around a quarter of the time immersed in dreams, which suggests they must have a purpose. But what? Many theories exist to explain why we dream. Most of us have experienced dreams that have helped us to work through difficult thoughts, emotions and experiences, leaving us feeling more balanced in our waking hours. One theory supports this, suggesting that dreams are a way to reset our brains, reflect upon and explore the day’s issues and to consolidate.
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REM sleep is when our brains get everything out onto the metaphorical table, figure out what’s there and then sort and bin, or match to existing memories and file accordingly. This suggests that REM sleep exists for the formation of emotional memory in humans. But that doesn’t explain why babies in the womb spend all their time in REM sleep despite having nothing to resolve. From this point, dreaming declines throughout childhood, which indicates that dreams are part of how immature brains function. Their modest neuro-wiring needs help to join and establish connections, and REM sleep does this very thing. But there has to be a huge benefit to REM sleep throughout our lives because of the way the brain fights for it to take place.
If you’re woken during REM sleep (and therefore likely to be dreaming), your brain will try to compensate the following night and you’ll enter REM sleep more often and for longer. One experiment woke participants every time they entered REM sleep. On the first night this was up to ten times but after six nights of repetitive waking their brains tried to enter REM sleep as many as 33 times. Parents of wakeful babies will know this feeling well, which results in dreams and reality often becoming extremely blurred.
We’re not alone in our dreaming ways. All mammals appear to dream as well as birds, occasionally. And it’s this that gives weight to the theory that dreaming is merely a neurological response to biochemical changes and electrical impulses. During our dreams, the brain unites experiences from the past, present and future; processing information from the first two prepares us for the third. Alternatively, this implies that dreams have a protective role, preparing us to face threats, dangers and challenges.
Depression and anxiety can provoke nightmares as can post-traumatic stress disorder, lending weight to the theory that dreams are the brain’s way to sort through difficult thoughts, emotions and experiences. Because much dreaming activity takes place in the right hemisphere, one final theory looks at its role as a creative portal fuelling creativity and problem solving. Lucid dreaming – where you can train yourself to influence or guide your dreams to take a certain route – is one way to solve real life creative problems. One study looked at the dreams of musicians, who dreamt frequently of music and nearly half the songs they recalled were unfamiliar and new. Can you compose in a dream? Yes! Paul McCartney famously recalls that the melody to ‘Yesterday’ came to him in a dream. Does dreaming exist to generate a creative landscape for the mind, then?
Beyond all these theories, the cause and function of dreaming still remains unknown and it's difficult to know why we dream. Insightful, healing or a biological function, where we go when we sleep is still a mystery. But there is delight in the not knowing, too. The secrets of sleep have become the stuff of plays, poetry and literature. The stuff that dreams are made of.
Illustrations by Matilda Smith.