We all sleep, just as we all breathe, eat, and have blood pumping through our veins. It’s impossible to imagine life without sleeping because, well, life just isn’t possible without sleep. And while we all readily acknowledge this truth, it’s interesting that we often fail to ask the pertinent question: why do we sleep? Sure, we all go to bed every night (regularly, on a strict schedule, right everybody?), but the question of “why do we sleep” is so rarely addressed, especially since sleeping constitutes roughly 1/3rd of our lives.
Sleep is Antisocial
Compare sleeping to eating. When we eat, we’re using the now innate ability our species developed over millennia to turn consumables (corn, beef, corned beef, etc.) into the nutrients our bodies use to grow, repair, and function. We’re all aware of why we eat, diet science has shifted into pop science and even skipping a regular meal by an hour or two will cause notable changes in our comfort level. We get hangry, so we try to keep our eating to a schedule.
Now, why don’t we talk about the role of sleep on our bodies more often? Sleeping in is seen as sloth, sleeping early is seen as boring, and being tired is seen as weakness. Our modern culture has dictated that sleep is the enemy, something to scorn rather than embrace—in part because of this pervasive cultural norm, quality sleep isn’t given the positive attention it deserves. So we ask: why do we sleep? What’s the purpose of sleep and why should you go to sleep for 7-9 hours of every 24-hour cycle? Why give up the nightlife for the bed life?
Why Do We Sleep—Because We Have To!
Well, it’s important to remember that you must go to sleep—when you sleep, your brain performs a number of important tasks that keep your body and mind functioning properly. When you sleep, your brain isn’t just resting, it’s very active! There’s so much going on in there!
Memory and Sleep - Sleep is necessary to consolidate memories so they can be recalled in the future. Memories work pretty simple when you break it all down; your brain takes the acquisition of a new memory or experience (while awake), consolidation, which sorts that information (while asleep), and prepares it for future recall (while awake). Studies show that if you get a decent night of sleep after learning, your brain sorts short-term memories into long-term memories and you’re able to recall significantly better than when you get inadequate sleep. In contrast, this is exactly why you shouldn’t pull an all-nighter to study!
Spring Cleaning - Dr. Michael Breus, Ph.D. Notes that “The brain removes protein and hormonal waste during sleep to keep its cells functioning.” When we sleep, the cerebrospinal fluid that circulates throughout the spinal cord and brain increases in volume (according to this 2019 study). What Nina E Fultz and her team theorize is that the purpose of this increased circulation is to clear metabolic waste products from your brain that build up throughout the day. Out with the old, in with the new!
Physical Restoration - Like a Renaissance painting slowly fading behind the altar of an Italian church, the brain requires restoration periods to reverse natural damage—the normal wear and tear of the brain. While you sleep, your brain is boosting its metabolic stores, reinforcing connections, trimming unneeded synapses (aka forgetting the connections between things), producing myelin sheaths, and becoming more energy efficient. Your brain has to cut unneeded information to make room for new stuff and repair damaged cells. Why do we sleep every single night? So we can keep our brains healthy!
Dreaming - Why do we sleep if our brains are still going to remain active through the night? Do you remember your dreams? Whether or not you do, we all dream (particularly during REM sleep). The importance of dreams is likely (though this isn’t entirely proven) to help us process complex concepts, sort through trauma and stress in a safe environment, and conceptualize the abstract. Whether you’re having a nightmare about the office or flying through the sky, dreaming is part of your brain’s process of making sense of this wild world.
A Sense of Well-Being - During sleep, we can see brain activity increase in the areas that regulate emotion, like the amygdala, hippocampus, and medial prefrontal cortex (among others), suggesting that proper brain function and emotional stability require consistent sleep. Your amygdala is related to the “fear response.” When you’re sleep-deprived, your amygdala is more likely to overreact and cause unnecessary stress compared to when you get adequate sleep.
Weight and Sleep - Two important hunger-related hormones are affected by sleeping; ghrelin, which increases your appetite, and leptin, which increases satiety. They’re essentially opposites, so when you sleep your ghrelin decreases and leptin rises. When you’re awake, the opposite happens (which is why you get progressively hungrier throughout the day if you don’t eat). Sleep deprivation leads to an imbalance of excess ghrelin, making you hungrier, whether you need extra calories or not.
Sleeping is Essential to A Healthy Life
There are many things that can go wrong if you don’t get enough sleep—failing to get the allotted 7-9 hours you need can cause mood swings, anxiety, depression, poor memory, lack of focus and concentration, fatigue, poor motor skills, weight gain, high blood pressure—you name it!
Sleep is such a vital part of enjoying a functional, enjoyable life, yet so many of us take it for granted in the modern world. With more and more distractions to keep us up at night, longer work hours and seemingly endless things to check off the ol’ “to-do” list, it’s no wonder we collectively don’t get enough shut-eye. But despite the distractions, it’s important to remember that we must treat sleep as the necessity it is in order to live well and craft a bedtime routine to make sure we stick to it!
So… why do we sleep? Simply put, sleep is the time where our brains do the hard back-end work—sorting and storing memories, physically repairing damaged cells, cleaning up the unnecessary junk, regulating our hormones, and helping us subconsciously figure it all out. Next time you’re thinking of staying out late and catching up on zzz’s another day, think again! If you don’t get enough sleep, you might not even remember to do it at all.