Gone are the days when we thought that our brains go to sleep with our bodies at night. We now know that the brain never sleeps (although it may, at times, take a rest during boring office meetings or anthropology lectures).
We–if we’re smart–spend one third of our lives asleep. For some, that seems like a waste of time. But sleep is crucial for good health and more: our brains are freed up from conscious activity to catch up on the homework.
Neural activity during sleep is almost at the same level as while awake. So what are we doing without knowing that we’re doing it? Besides regular involuntary bodily functions like digesting food, breathing, sending signals to organs to keep working, etc., your brain is conducting more active cognitive processes than you may realize–all the more reason to embrace sleep as your very good friend.
Here are just five purposes of sleep from the brain’s perspective (this is by no means an exhaustive list).
1. Creates and Consolidates Memories
We need our brains and bodies to be well rested in order to form new memories. During sleep, our brains take new memories, solidify them, and connect them to older ones, making for a consolidated memory network. If you keep forgetting where you put your car keys, it might be because you’re not getting enough sleep.
“Sleep and sleep deprivation bidirectionally alter molecular signaling pathways that regulate synaptic strength and control plasticity-related gene transcription and protein translation…sleep oscillations before encoding refresh human hippocampal learning capacity, while deprivation of sleep conversely impairs subsequent hippocampal activity and associated encoding…the unique neurobiology of sleep exerts powerful effects on molecular, cellular and network mechanisms of plasticity that govern both initial learning and subsequent long-term memory consolidation.”
While you sleep, the entire body works to clean house–literally. Toxins that have built up during the day can be processed and sent to the appropriate organ for expulsion. It is known that chronic lack of enough good-quality sleep can lead to neurodegenerative disease like Alzheimer’s.
The reason why this is: when hormone levels drop during sleep, the glymphatic system releases cerebrospinal fluid around the brain and spinal cord, washing away dead cells and flushing out toxins.
Without this nightly process, contaminants can accumulate, affecting memory, alertness, and long-term brain health.
3. Learns and Remembers How to Perform Physical Tasks
People twitch while dreaming because they are practicing physical activity. While in the REM (rapid eye movement) sleep state, information is stored into long-term memory as the result of “sleep spindles”: short bursts of brain waves.
It’s thought that these energy bursts occur when the temporal lobe receives new memories from the motor cortex, processes them and stores them. Sleep deprivation blocks the new information from being saved into memory:
“Practice during sleep is essential for later performance. If you want to improve your golf game, sleep longer.”
4. Making Creative Connections
Sometimes our mind gets in the way of our brains–and vice versa. When it comes to creativity, sometimes we unconsciously put obstacles in our own way (e.g., writer’s block) and we get stuck.
Our subconscious doesn’t have this problem. It can think how and what it wants, ignoring the blocks and using imagination. The result is increased creativity: we develop associations with what we already know and what we imagine, leading to new ideas and potential for how things could work.
Without enough sleep, one study found, relational memory doesn’t work as well and we don’t make the connections we could with enough high-quality sleep.
5. Making Decisions
While the body is asleep, the brain processes the information it has received throughout the day and works through problems to provide answers.
A study published in the journal Current Biology tested the theory that we still process outside stimuli based on recent learning while we sleep. Subjects were asked to classify words as either animals or objects, pressing the button on a responder with either the left or right hand to signify one or the other.
After they had fallen asleep, researchers continued to speak out words; the subjects’ hands responded with motor movement of either a left or right hand in response to each word, just as they did while awake.
“There is now converging evidence that environmental stimuli can still be processed during sleep, at least to a certain degree…we show that sleeping participants are still able to prepare for the appropriate response on semantic and lexical decision tasks practiced before falling asleep…These results not only confirm previous findings showing that semantic information can still be extracted during sleep, but further show that this nonconscious meaning extraction can be routed by the task context and reach higher processing levels, up to motor preparation stages.”
With so many important reasons to ensure adequate sleep, be confident you can’t fool your brain into thinking it needs less–you will notice the consequences of skimping.