What is the reason behind the need to “fall” asleep rather than choosing to be asleep?
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For much of our evolutionary history humans were “dumb animals”. Our bodies are composed of many different systems that must act in concert without a coordinating intelligence. They do this via many “signals”, behaviors which other systems react to resulting in our bodily functions.
This is the case in the brain as well. Different parts of our brain are constantly in competition with each other, the net result being our behavior. This can be illustrated by considering an example of when things go wrong: With ADHD some parts of the brain are constantly coming up with ideas and things of interest, while another part of the brain is responsible for moderating those urges, ignoring what isn’t important and focusing attention on what is. Those with ADHD have low function in that part that moderates attention, which results in the seemingly paradoxical effect that stimulants help those suffering ADHD to calm down and focus. Stimulants we would expect to make someone hyperactive instead can help those with ADHD settle and stop fidgeting, all because of the interaction of those separate systems.
With sleeping you can have one system saying that you are tired and should rest, while perhaps another is telling you to eat, and another is saying you are in danger. Without some intelligence to choose a correct behavior our bodies need to form a behavior based on input from all those systems; it wouldn’t do to fall asleep while in danger!
So while we have what we feel is a cohesive intelligent mind, it exists on top of all these interacting systems without us having any direct control. Instead we must just satisfy them sufficiently to motivate the desired result.
We can only actually choose to do two types of things:
1. think
1. move muscles
We can’t choose to sleep any more than we can choose to digest food or choose to change our heart rate.
If we made a choice to sleep, we wouldn’t actually be sleeping. The point is to let the body’s systems rest by slipping into a state of unconsciousness— choice necessitates consciousness, so if we *chose* to do it, we would need to remain conscious in order to maintain it, therefore defeating the purpose.
I’ll take me stab at it, I’m no scientist or anything so keep that in mind.
Sleep is less of an action (like picking up a cup and setting it back down) and more like a full length process. You may have heard of “stages” of sleep, such as R.E.M. (Rapid Eye Movement) all of these stages play an important role in the overall goals and effects of sleep on the body. Even while asleep, our brains are still active! Electrical signals fire, things happen with memory, the body heals and grows, etc.
Our brain can’t gain the benefits of sleep instantly, and the best that our evolution has so far produced is this very slow lengthy process of the brain going through these many stages of sleep, back and forth, before it and the body have achieved “rest”
To choose to do something would also probably mean that we would have to be awake to do it. Part of being asleep is your active, thinking mind is turned off for the most part, so that those cycles of sleep can occur the way they need to. It takes time for brains to do this though, which is why we don’t have to worry about accidentally falling asleep if we were to blink too long.
Basically because we weren’t designed to be perfect humans in current day.
But evolved over millions of years.
It started with bacteria that had biological clocks to regulate their metabolism.
And throughout evolution to more complex life forms and eventually mammals and humans, more and more complex systems were added on to the body, and later to the primitive brains of amphibian like animals etc.
So sleeps works like it does for us; because it’s a barely working amalgamation of various time keeping and resting-maintenance systems that came about by random chance and were good enough to make our far away ancestors reproduce.
Additionally having the capability to consciously fall asleep and that not be extremely dangerous; would kinda require a fully sentient being.
Even for our more closely related prey mammals siblings; having that ability would just lead to problems. A deer just ‘random lt’ deciding to fall asleep? On what basis would it decide to do so?
So all of the brain and body has developed a tightly regulated system of basically comparing two signals: one is the body and brain saying ‘i need Rest’ and the other is the body and brain saying ‘we need to be awake because it is dangerous here, we are not yet done feeding for the day etc’
And the we need to rest signal will just continuously get stronger, until for animals that active in the day, it will in the evening make the brain go ‘better get into resting mode, and slow down the awake systems and go into restoration mode’.
This is caused by molecules like adenosine accumulating throughout every waking second; or melatonin which is being produced once it starts getting dark, or cortisol which is released in the very early morning to jump start you.
This way, baring disease, it leads to falling asleep when the body and brain needs it, and it is safest to do for the degree of need to be asleep.
Since all of these systems have evolved long before conscious though and sentience, they simply continued working like this once we became sentient. Because it’s good enough.
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