eli5: How does lack of sleep kill someone?
In: Biology
A lot of vague and wrong answers here, OP. The truth is that we don’t necessarily know that lack of sleep can kill a human. The longest anyone has officially been awake is around 11 days, although unofficial attempts have been reported that go on a bit longer (Guinness World Records stopped recording attempts to deter people). None of those people died, and all made full recoveries as far as recorded data knows.
Note that we’re not talking here about Fatal Familial Insomnia, the prion disease that someone else mentioned. That’s a degenerative disease which literally turns your brain into a sponge-like structure. Like most degenerative disorders, the likely cause of death with FFI in the end is failure of autonomic function like breathing and swallowing. It’s debated, but lack of sleep is generally not considered the fatal aspect. In any case, it’s a different thing from lack of sleep.
The evidence that acute deprivation can cause death comes from animals – this has been demonstrated in a few species, most notably rats. These studies suggest stress-related problems including reduced immune function and cardiovascular stress which may lead to death. The suggestions that others have put forward (e.g., brain waste removal) have either not been supported or not been investigated in such studies. However, evidence from animals is also mixed to some extent – for example when some flies are genetically altered to not sleep, they do not die from the sleep deprivation.
Does this mean that sleep is not important? Absolutely not. We know that chronic sleep deprivation (even just getting less than ideal amounts each night) can cause cognitive problems and is a risk factor for various disorders from depression to dementia. We don’t know the explicit function of sleep (we see various processes such as waste removal, memory consolidation, etc. which are optimised during sleep but not necessarily dependant on it), but we know it’s likely evolved as a specialised and functional stage of our being. We also see it in some form in every known species, which again highlights its importance. That does not mean we have concrete evidence for acute sleep deprivation being lethal, though.
TLDR: sleep deprivation won’t necessarily kill you. We don’t have good evidence in humans showing it will. Sleep is very important for health but lack of it might not explicitly kill you.
edit to be more explicit: no one reading this will die of sleep deprivation. never been recorded, ever. sleep well folks
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