A question that occurred to me while waking up (appropriately enough) this morning: when surgery has to be done on someone who tosses and turns constantly in his/her sleep, sleepwalks, or snores, surgeons don’t do anything different for them, as far as I know. So why don’t those problems present themselves when they’re under the influence of anaesthetics (the kind that make you unconscious, of course)? What’s the difference between that state and normal sleep? For that matter, why don’t coma victims snore? Is that a related issue?
Bonus question: Firefox flags “anaesthetic” as being incorrectly spelled. What does it think is the right spelling? As far as I can tell from Google, it’s the right one.
Just a WAG. But being put under by the doctor is a lot like just being knocked unconscious. Its an incredibly deep sleep. I’m not an anesthesiologist but i believe there are some paralyzing drugs in the concoction.
It is expecting “anesthetic” which is a common North American spelling while “anaesthetic” is preferred in the UK. Firefox (US version, at least. I can’t speak for a UK-localized version) tends to mark UK variants as misspelled in favor of US variants.
ETA: A Google search shows that “anaesthetic” brings up a lot of hits from UK government and university sites. “Anesthetic” brings up US academic and government sites.
They give you more than just a sleepy drug. When you’re under “general anesthesia,” you typically get paralytics to keep you from moving, and painkillers to…kill pain. Just because you’re asleep doesn’t mean you couldn’t get woken up from the pain if it was severe enough…I know I’ve woken myself up from pain several times.
ETA: There are of course cases where some of the drugs they gave didn’t work or weren’t enough. People have reported waking up during surgery in incredible pain and not being able to tell the surgeons, because they are still paralyzed.
Well, it’s complicated. I can’t speak too much to the effects of anesthesia on the brain and consciousness, but I can tell you that sleep is not just the absence of wakefulness, it is a dynamic process characterized by well-organized changes in brain activity.
A typical sleep cycle consists of 4 distinct stages: Non-REM 1-2, Non-REM 3, Non-REM 4, and REM (rapid eye movement) sleep. As you fall asleep you first enter Non-REM 1-2, which is a very light sleep. During this stage, brain activity differs only slightly from awake activity. As you enter Non-REM 3, you fall into a deeper sleep and the brain begins to exhibit synchronized activity in the form of sleep spindles (~10-15 Hz bursts of synchronized activity). The deepest sleep is Non-REM 4, during which the brain exhibits delta waves, which are ~4 Hz waves of activity that propagate throughout the cortex. Eventually, you transition into REM sleep (a.k.a. dream sleep), which is characterized by brain activity that appears similar to activity seen during wakefulness. From REM sleep you wake up (sometimes) and start the cycle over again from scratch. So, as you sleep your brain is always active and processing information. The same cannot always be said of a brain under anesthesia.
Different anesthetics have different effects. Some anesthetics acts as a paralytic, some act as an analgesic, and others may act to retard memory. Most of the time different anesthetics are used in concert in order to produce the desired effect of “knocking someone out”.
Some anesthetics also (intentionally or unintentionally) cause changes in brain activity (I’m not entirely certain of all the changes that occur, we need an MD to come and answer that one). For instance, in neuroscience research, scientists need to carefully consider their choice of anesthesia when recording brain activity. Some perfectly wonderful anesthetics will significantly change brain activity, while others will effect a specific type of activity (such as how the brain responds to sensory stimulation) or a specific area of the brain.
Just adding: as bouv said, that’s general anesthesia. There are other options for special situations. For instance, one of my sons had to get an MRI when he was a year old. He was given a form of anesthesia that included the paralytic drug and a smaller-than-normal dose of the sleepy drug, but no painkillers. The idea was that he would lie perfectly still so the exam would go quickly, and would be deeply enough asleep that the strange noises wouldn’t worry him. But since the MRI is completely non-invasive, the painkiller part was unnecessary.
The anesthesiologist told me he was more deeply asleep than if he’d just dozed off on his own, but not as deeply asleep as if he’d been under general anesthesia for surgery. He woke up very quickly and in a great mood, and enjoyed all the fussing over he got from the nurses in the recovery room
