What is the physiological difference between sleep, unconsciousness and anaesthesia?
In: Biology
Not a super technical answer but as someone who’s gone under for surgery, when you’re asleep you’re still aware to some degree of time passing, you’re having thoughts and whatnot. When I went under I remember breathing in the gas and then it was like I blinked (literally like just blink it was that fast) and I was in a completely different room hours later.
Neurophysiologist in the Operating Room 15 years experience: lord butterfingers is correct. Read his reply: and (my career) is responsible for measuring, documenting, and interpreting the effects of anesthesia on nerve activity vs. surgical effects of nerve activity. Brain / spine / nerves / muscles : all of it.
ELI5: sleep- your brain is in control of your sleep: brain monitors your body while in sleep: any external stimulation or change or noise or cold or hot or anything: the brain and body wake up and respond. Your brain allows body to move while you sleep. (Breathing, roll over in bed, flop you legs around when they get uncomfortable, pull the covers up if you cold, kick covers off if you get hot)
General Anesthesia: anesthesia professionals monitor your sleep: professional sedate your mind, reduce your threshold for pain, and most of the time they relax your muscles. Any external stimulation does not get registered by your brain and your muscles are relaxed so there is no response: your body can not breathe on its own: it can not roll over , can not pull up the covers, can not kick the covers off, and if you your blood circulation in your legs get reduced (like the feeling when your foot falls asleep ): under general anesthesia your body will not be able to respond and adjust itself under general anesthesia: that is why you have professionals monitoring and taking care of your anesthesia AND the neutral position of your body so your legs are not falling asleep because your ankles are crossed for several hours: and yes: we check all of that in surgery while you are asleep! KEY Point: it is controlled, monitored, and quickly reversible at end of your procedure. I.E. you wake up and return to normal function within a few min. Of time.
Also: different anesthesia drugs have different effects n EEG: and any combo of drugs as well.
Unconscious: ELI5 – the the mind is protecting itself and your bodies vital organs only: something caused the brain to go into critical status: so instead of the brain monitoring every single body function while you sleep normally: now it is only monitoring g the basic functions: this is not controlled by an anesthesia professional: and there are different levels of what the brain is controlling / functioning and what is not: but the key point is the brain chooses to stop control over various body functions on its own (for whatever reason) and when the brain is ready to resume responsibility- it will resume control on its own: (depending on level of trauma / damage / reason in the first place). Think about a choke hold from two kids playing rough and play wrestling- and one kid just holds the choke hold a bit too long and his friend passes out: unconscious kid collapses and looses muscle control and tone: then kid starts to breathe as soon as the hold is released : then the kid Opens his eyes within 5 seconds: feels a little dizzy for 15 seconds: then is back to normal. This kid’s Brian only shut down a few functions and only for a few seconds: this kid did not loose lung control, bladder control, blood flow to his extremities, blood glucose control, or any other major system control. now think about the traumatic car wreck where patient is ejected from a vehicle and suffered massive blood loss and head trauma: this patients brain will shut down several functions for a very long time while the body ( and brain) recover.
Now think of the patient that is actively having a seizure and looses consciousness. This is electrical brain activity spikes that confuse the brain: and it gets overloaded an has to shut itself down: and even a 30 second seizure can cause bladder to empty, can cause vomiting, can cause the patient to bite his tongue off. OR some seizures cause no muscle issues what so ever: some seizures can happen to a girl sitting in her desk at school: seizures can last 30 seconds: and this girl will look to her classmates and teachers completely normal: but the reality is her brain is resetting , her eye lids may be closed for 30 seconds, or she may appear to blinking rapidly for 30 seconds: but she does not even slouch her head or shoulders: she does not fall over, she does not loose bladder control and she does not vomit: she does not bite her tongue: she just sits still and silent for 30 seconds.
All the examples I have given look different on EEG. Time, electrical frequency, even different medications “knock out” the eeg patterns in different ways.
Hope this helps
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Yet another computer analogy, here we go.
Sleep:
*windows xp shutdown sound*
*windows xp startup sound*
Although really it’s more like entering low-power mode, defragging, and emptying the recycle bin. A lot of miscellaneous cleanup. [Edited for accuracy]
Unconsciousness: *your system has encountered an error and needed to shut down*
Technically unconscious refers to any time you are not fully awake and aware iirc, but traditional “knocked out” unconsciousness is basically a BSOD.
Anesthesia: Your brain is running normally but with no programs open. No (or very little) data is being written, recorded, or saved to any form of memory.
Lets try and relate this to how you might see it with a computer.
Sleep: Is an orderly process of shutting down. Buffers are flushed and processed are stopped in an orderly and predictable manner. And becoming awake is the reverse where things start back up in a similar orderly manner.
Anesthesia: Is more like a suspend or hibernate mode. There is no gradual shutdown, you are running like normal one moment and the next you are not running (so to speak). Aside from baseline processes everything is just stopped or suspended.
Unconsciousness: This ‘normally’ happens when something goes wrong. Going into shock, having a bad reaction, getting hit in the head, etc. It’s like your computer crashing and getting a BSOD. Notable is the loss of data (like in a blackout): one moment you might be fine and the next you are laying on the floor with no memory of anything in between the two.
I probably butchered this bad but you should get the point.
Oo! I recently read an [article](https://bigthink.com/mind-brain/anti-correlated-consciousness?utm_medium=Social&facebook=1&utm_source=Facebook&fbclid=IwAR02lxf7JVgFfVHDWcf1_xSledfUkdz6biR0VMffD1YsHJLqY-yqJURYdKs#Echobox=1588705444) that elucidated a bit on this subject. Basically there are two neural systems (DMN and DAT) that when in complete balance results in unconsciousness and when out of balance leads to consciousness. The article has a great eli5 explanation:
“Imagine you and a friend want to go out to dinner but you want Chinese food and your friend wants pizza. If both of your preferences carry equal weight, nobody gets to eat. Let’s say that’s like unconsciousness. But when one of you gives in, yum: Consciousness.”
I suppose you could start with sleep being a state from which you are rousable, whereas unconsciousness and anaesthesia are not.
The physiological differences are probably better explained by a neurologist, but the EEG (brainwave) features of sleep are different to those in anaesthesia. Sleep has different wave findings depending on your stage – REM has quite an active EEG, deep sleep less active etc.
Anaesthesia (general) is a different beast. It’s a drug-induced reversible state of reduced consciousness, pain relief and (much of the time) muscle relaxation. It is not a rousable condition – the entire point of it is to stop you from feeling/being conscious of the goings ons in the operating theatre. Depth of anaesthesia can be measured by EEG, and the findings are characteristically less active. The anaesthetic drugs we use essentially switch off the neurones in the brain; this doesn’t happen in sleep. If you give enough of an anaesthetic drug you can even induce isoelectric EEG – i.e. no activity at all.
Unconsciousness – physiology depends on the cause. If it’s a brain bleed, you’ll have different brain activity to say, a seizure lasting 40 mins. They’re both unconscious states if you’re not rousable. General anaesthesia could also be described as controlled unconsciousness.
Source: anaesthetic/ICU doctor
Edit: there have been quite a few complaints that this isn’t very ELI5 – I agree, sorry. I was responding more to the question and when it used a term like “physiologic” I assumed a bit of knowledge to be honest. I don’t think any of the analogies I’ve seen are accurate enough to describe the differences so I haven’t reappropriated them. Feel free to ask questions if you don’t understand though, I’m trying to get round to answering most of them.
Simple version –
Sleep: someone can wake you up if they poke you hard enough. Your brain is listening and ready for it. Imagine needing it so you don’t get eaten by a bear clomping around in the middle of the night.
Unconsciousness: no matter how hard I poke you, you’re not waking up (but you’re still alive). Your brain is on vacation and forgot to leave an out-of-office email.
Anaesthesia: same as unconsciousness, but in a controlled fashion.
I’m no expert but this is what I understand. Sleep is regenerative and has cycles that help us remember things and get ready for the day.
Anesthesia: I’ve heard scientists still don’t understand how or why it works. Some say it has the ability paralyze us for operation BUT THE REASON it works out well for the patient is because it prevents us from forming memories. So your body is still feeling everything but it’s not traumatic because you can’t record anything.
Unconsciousness would be essentially soulless. I’m guessing your body could be alive with machines but without a response from the person I’m guessing that would be unconscious.
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