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.