What stage of sleep are you in under anesthesia, and why does it feel like no time has passed?

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What stage of sleep are you in under anesthesia, and why does it feel like no time has passed?

In: Biology

13 Answers

Anonymous 0 Comments

Technically, you aren’t sleeping. General anesthesia stops certain brain functions and places your brain into a state of true unconscious. This is why anesthesiologists are so important, because it’s a very fine line between the amount needed to kncock someone out and the amount needed shut down too much brain function and kill them.

Interesting fact, unlike local anesthetics which paralyze the nerves to reduce or eliminate pain, general anesthesia doesn’t stop your nerves from sensing or sending signal. Studies have been done that show that people’s nerves fire like crazy during surgeries, but the general anesthesia prevents the brain from registering it.

Anonymous 0 Comments

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Anonymous 0 Comments

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Anonymous 0 Comments

General anesthesia does not produce sleep. Sleep is actually a pretty active state and general anesthesia produces greatly reduced levels of brain waves and also ceases production of others. Most brainstem functions remain intact and can be manipulated depending on the depth of anesthesia. Higher level functions such as memory formation, sensation, processing, and response are stopped. Basically you can crudely divide the brain into response and staying alive functions (brain stem and lower centers) and higher level responses. General anesthesia unplugs the higher functions while generally keeping the bodily functions running. We do have to manipulate some functions with medications or lowering the level of anesthetic being delivered.

Anonymous 0 Comments

The first person to actually answer your question would get a Nobel prize. Nobody knows why or how anesthesia works.

Anonymous 0 Comments

Anesthesia does not cause sleep, it causes loss of consciousness. When you’re sleeping, your conscious mind is inattentive but still present and it can be woken up by stimuli from the outside world. When a person is under an anesthetic it prevents conscious thought all together, and the persons mind is effectively switched off. I say mind and not brain, because the brain continues to function, but thoughts and the ‘mind’ do not.

To make an analogy, if your mind is a computer program, running on a computer called the brain, then anesthesia is hitting ctrl+alt+del and killing consciousness.exe for awhile. Where as sleep is more like setting it to run in the background with decreased priority.

Anonymous 0 Comments

TL;DR: You’re not in a stage of sleep when under anaesthesia, you’re in a state of low brain activity throughout (which results in loss of consciousness, inability to respond to your environment and memory loss). When you’re asleep however, you are in an altered conscious state, and still very able to respond to things!

Effectively, being under anaesthetic is the deepest ‘sleep’ you can be in. A key part of talking about sleep or comas or anaesthetic is consciousness. Consciousness in a medical context is your ability to respond to stimuli (a detectable change)- so for example; if I shine a light into your eye, your pupil should constrict; if I strike just below your kneecap, your knee should jerk upwards and so on. These responses are important in assessing someone’s nervous system and brain responses- and you might often see them done on coma patients on medical dramas.

The fact is with sleep, you are still very much ‘aware’ of what is going on- you’re easily awoken and alerted if nudged or if yelled at, you still exhibit the above reflexes and so on. Sleep is very predictable, it has characteristic brain activity, metabolic activity etc.

Anaesthesia however is different, anaesthesia aims to cause unconsciousness, pain relief and amnesia. Someone under anaesthetic would not normally wake if you hit them or yelled at them, they wouldn’t react. If you shone a light in their eye, it wouldn’t constrict. Anaesthesia impairs your body’s natural nervous responses to these things by inhibiting along your central nervous system.

While you’re awake, your brain is sending excitation signals and inhibition signals all the time all around your brain. For a nerve cell to send a signal it needs to pass a ‘threshold’ of electrical activity to actually ‘fire’ the signal. Therefore, nerve cells themselves have components that excite them (yeah this signal is worth firing over!) or inhibit them (nah this signal isn’t worth firing over).

Anaesthetics, it is believed, work by increasing the strength of these inhibitory processes in the brain. One example of these inhibitory components is called the GABA receptor, a lot of people think anaesthetics make these GABA receptors more able to inhibit/depress the nerve cell so it won’t fire. By doing this all across the brain, the amount of excitation starts to drop.

The signals from your hearing drop, along with your eyes and nose. Signals from your skin telling you how warm or cold it is diminish. Your thoughts begin to quieten and silence, while your very wakefulness begins to fail. And all of a sudden you’re awake, with no memory of what happened, no pain and feeling a bit tired.

The exact mechanism how all this happens isn’t entirely known. But we do know there is a huge drop in brain activity due to anaesthetics. The quietening of these signals simply appears to put the whole central nervous system in a quiet standby state- your pain responses and memory systems just sort of say “meh” and don’t bother to fire to trigger pain or to make memories throughout.

So to sum up, anaesthesia isn’t normal sleep. Sleep is a natural thing many animals do, it is tied in to our natural healthy metabolism. Anaesthesia is effectively the application of drugs to try and ‘quieten’ the central nervous system, and it does it well. So well that it quietens your ability to make memories, feel pain and respond to any stimuli. These traits make it very unique and not as natural compared to sleep.

Here’s a few links about anaesthesia:
https://www.tuck.com/anesthesia/ (Easy to read quick overview)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3162622/ (Academic overview of the nature and differences between coma, sleep and anaesthesia)

http://serious-science.org/difference-between-sleep-and-anesthesia-1160 (nice short article about the differences between sleep and anaesthesia, in reference to Michael Jackson’s death)

Anonymous 0 Comments

I had hip replacement surgery recently. The anesthesiologist said they would be using a spinal block and bringing me in and out. Little did I know this would mean that I would become conscious during the procedure. At the beginning they placed something in between my legs, butted right up to my crotch. I felt them placing it and asked if they had put a chastity belt on me. Apparently the medical profession doesn’t share my sense of humour as someone rattled off the name of the device and then I was immediately knocked out. I wasn’t able to speak again but I was conscious a couple more times and could hear suction and felt the Dr. pounding the new hip into my bone. This type of thing happened during one of my C-sections too. Fun times.

Anonymous 0 Comments

Follow on Q: do you feel “rested” following general anaesthetic? For example would it take the place of sleep, or does your body not get the same recovery?

Anonymous 0 Comments

It’s crazy when u really pay attention to the feeling right before you lose consciousness. It feels like you’re gonna explode lol