Eli5: Why do we need to sleep so much, what happens in the body when asleep that cannot happen while normal resting or relaxing? Or is it just for the brain?
In: Biology
So. Much. Stuff. So much. Here’s a quick overview.
Simplified, you sleep in a couple different phases: REM (Rapid Eye Movement, the dreaming phase), and NREM, often split into NREM 1 and 2/ NREM 3 and 4 (slow wave, “deep” sleep). Each of these types of sleep has a different job.
During REM sleep, all the stuff you experienced and learned during the day gets replayed over and over, along with other old memories that your brain tries to mash together, making new connections and strengthening memories. A lot of inspiration comes from dreaming, because you just can’t try out as many combinations of thoughts and ideas when you are awake. It’s extremely important for memory and brain development, like another person said. Dreaming is also very important for getting over traumatic events, as dreams will make you relive them, but a very important stress hormone in your brain is turned off, so you can process the grief and other feelings without the trauma. PTSD, by the way, is what happens when this system fails.
In NREM 1 and 2, one of the cool things that happens is that “muscle memory” is developed. Ever practiced something, got frustrated and stopped, and after sleeping on it, suddenly been able to do it? Your brain practices in your sleep. If you’re trying to learn a new skill, make sure to get enough sleep.
Deep NREM is the part where your brain reorganizes everything. Useless memories out, important memories saved and put into long-term storage. This part is extremely important for reducing anxiety and stress, as well as memory. Not only does this help you remember the things you learned from that day, it also clears up your short-term memory storage (basically like RAM) so you can start again in the morning. Don’t underestimate the difference this makes. You can’t put memories into long-term storage while awake, and you are losing them constantly as new ones replace them.
Your blood pressure also goes way down, your heart gets some TLC, your whole body gets restored. Like another user said, toxins are flushed out. One important “toxin” is so-called amyloid plaque, a mess of proteins that you produce, and that get caught in your brain, every second you are awake. These destroy your brain and memory if allowed to keep growing unchecked. The *only* way to get rid of them is to get enough high-quality sleep, every night.
These proteins are the reason older people get diseases like Alzheimer’s: older people are often not able to sleep for as long as younger people. That is why it is so important to protect yourself from amyloid plaque by always getting 8 hours of sleep.
I will stop now, but there is so much more happening during sleep, and so many studies proving it. Please ask if there is anything else you want to know!
**TL;DR:** Body and brain are restored, memories processed, consolidated, and sent to long-term memory, stress, anxiety, and trauma reduced, blood pressure reduced, muscle memory developed, brain growth/new ideas. Yes, 7-8 hours of sleep are necessary, even for the people who feel okay after less.
Latest Answers