we sleep when we get tired, yes. but how do we get up rested? i mean our body keeps on working and working. which means we keep consuming energy right? so how do we feel more energetic, more rested as we wake up?
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As we stay awake our body produces the chemical in our brain called ‘adenosine’, adenosine has many uses but it primarily regulates our heart beat. But as a side effect this chemical causes us to become sleepy.
Our body uses sleep to rejuvenate itself in many ways, such as diverting energy to repair physical damage and fight off disease. It also breaks down the adenosine in our brain.
So when we wake up our body is clear of adenosine (not entirely but still) and we feel fully awake, and the process continues.
So our body uses adenosine as a sort of intensive to go to sleep so it can do those vital functions, same with how when we’re hungry our body makes our stomach hurt to give us reason to eat.
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What about those of us who wake up feeling as tired and crappy as we did when we went to bed? Even after 8+ hours?
Does that indicate our bodies aren’t clearing adenosine?
i do not know. but i guess it is because your brain is not taking any info in and process the input that makes one feel better.
As I understand, the body has a cleaning system. This system does not extend to the brain. The brain has it’s own cleaning system which only works at night. We’re still not entirely clear on the science as to why we need sleep and what all is going on, but this is the main function not occurring outside sleep which we need to stay healthy. (another important function is memory consolidation)
In short, we don’t really know how sleep works, because we don’t entirely understand how our brain works.
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Sleep is much more than just energy.
We evolved this to conserve energy during the night, when we were unable to do any task and we were just sitting in a cave.
During sleeping you use much less energy than just sitting beside a fire. Your brain is in power safe mode and your body is recharging its reserves all over the body. It is much more efficient to recharge muscles when they are not in use.
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Circadian rhythm governs this, which is mostly aligned to the day night cycle and it has triggers to move along like morning light hitting your skin.
The sleepiness is just an illusion your body communicating that you are “supposed to” sleep and recharge, to function normally.
But your body has many reserves in case of an emergency. Technically you can go 10-11 days without sleep, then your body shuts down.
A milder example is coffee, which interferes with the sleepiness, your brain doesn’t feel the sleepiness chemical called adenosine and thinks you are rested and you can go as usual.
But your body is dipping into the reserves and when coffee wears out, you crash. Your brain starts to shut down non-essentials to keep core systems going. Fun fact, your brain is not essential, that is why clear thinking the first one that is gone when you are exhausted.
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When you sleep normally, that sleepy chemical breaks down because your body doesn’t make it, your muscles don’t work, your organs don’t work that much, your brain doesn’t exert itself that much.
So a lower sleepiness chemical feels rested.
Keep in mind that the sleepiness chemical is different from physical exhaustion when you excercise. A totally different feeling. But later you feel sleepy sooner if you excercised a lot.
Matthew (Matt) Walker’s book on sleep is a very easy read or listen. He also does a great podcast, each episode is short and easy to understand.
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