What causes us to lose consciousness when we go to sleep?
In: Biology
We don’t. You’re not unconscious when you’re asleep. Your level of consciousness has just being altered. Unconscious means you’re not able to react to any stimuli. A sleeping person will react to stimuli that is strong enough, like an alarm clock. An unconscious person won’t wake up just because an alarm clock is going off otherwise that’s how they’d wake up people from a coma.
We should distinguish between strong stimuli (e.g. speech behind the door or a bump in the bed) and weak stimuli (clock ticking).
The brain then shifts between three stages: equalizing (strong and weak stimuli is equal in perception in the brain), paradoxical phase (weak stimuli are irritating, but strong ones are pacifying), and ultra-paradoxical phase (strong impulses are now accelerating the sleep even more and only weak ones are noticeable).
At the end of the ultra-paradoxical phase, there is little to be distinguished by the perception and then the boundary is blurred.
Have you ever been day dreaming, and then you realize your eyes were closed and you stopped paying attention to the world and you were starting to doze? Your brain was starting to go to sleep, then you woke yourself up. The brain begins sleep in stages that alter your awareness of your surroundings, and the activity of your brain. When you find it difficult to concentrate and your mind keeps going off on tangents thinking about things unrelated to what you’re doing, like it’s on a comforting auto pilot, it’s trying to fall asleep.
This day dreaming is the first stage, you relax and in a way you are sort of hypnotizing yourself. The thoughts become a distraction that makes you reflect and focus inward, instead of outward, and the more inwardly your attention lies, an more caught up in these comforting half thoughts, the more you slip into the early stages of sleep.
If you’re not disturbed and you are not trying to stay awake, this daydreaming leads to light sleeping. From that point on, you have the normal sleep cycle which would be a lot to explain.
One important step in the falling asleep process is somewhere between the dozing and daydreaming part of it, your mind put the parking brake on your body and sort of paralyzes you. This is for your protection so that as you daydream of running through fields of flowers, your legs don’t start running in place.
Sometimes if this sleep paralysis happens too early before you’re fully sleeping, or your suddenly disturbed in this state, you will have whats called a hypnic jerk. If you’ve ever fallen asleep at your desk and your head starts to roll off your hand and you suddenly snap awake, this is what happened. Your body’s emergency “turn off the paralysis!” button got hit and you literally jerked.
There are less fun ways to fall asleep though. The dozing, daydreaming type of sleep only comes when you’re relaxed and while tired, you’re not exhausted or seriously sleep deprived. Ironically the less sleep you get, the harder it is to get the good restful sleep you need.
Instead, if you’re very sleep deprived, or stressed, tired, exhausted, your sleep might come without the pleasant day dreaming. It might happen so fast, you sleep a few minutes, then wake back up, and never realize you were asleep, because the brain isn’t really going through stages of falling asleep so much as it’s just blanking out from exhaustion, then you wake back up because you’re tired and stressed. Some of the time when you are awake all night thinking you can’t sleep, you actually have slept, but it was the unfulfilling kind of emergency sleep of an exhausted person, not the restful sleep of someone comfortable and healthy. And you probably slept for only a few minutes at a time and not very deeply. To your perception, you were awake continuously.
All answers are going to be weak, because we don’t have a good idea of exactly what consciousness is or how it emerges. We don’t even have very good ways of studying it.
You aren’t unconscious, you’re asleep. That’s why they’re two different words.
You know how every so often computers need to restart to do updates and get their shit together? They don’t shut off, they just clear their working memory out so they can start fresh, and do some housekeeping that’s hard to do when you’re asking them to do stuff like calculate your finances in a spreadsheet.
The brain isn’t so different.
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