Death from sleep deprivation, what physical mechanism is failing that makes one not to be alive anymore? I have been reading on wiki about sleep deprivation it would appear that one can die without sleep... I have heard that it was used as torture method by quite a few agencies, but didn't know that one could die from it....

As far as I know REM is just brain running a simulation to improve long term memory by re-firing the neuron paths to make them 'stick' better... 

When death from sleep derivation occurs, what mechanism is failing that makes one not to be alive anymore. I mean there has to be some physical thing that breaks down, otherwise one would just loose consciousness and wake up in 40 hours or so...
As far as I know REM is just brain running a simulation 


During sleep hormones and neurotransmitters shift in their quantities available along the phases of sleep: slow wave sleep, intermediate stages and REM ( this happens several times during a typical sleeping session) and each phase brings corresponding highs and lows of the aforementioned chemicals. 

There is not a definitive and agreed function of sleep, but currently it is heavily tied to memory consolidation and metabolic regulation as well as a supporting role in the immune system.1  


  When death from sleep derivation occurs, what mechanism is failing that makes one not to be alive anymore.


Well, we don't really know,at least in humans it is not something we can really experiment, so most of the accounts are just that, anecdotes.

In order to try to answer the question, we unfortunately have to turn to the animal world, studies of Total Sleep Deprivation (TSD) in rats are perhaps the best researched ones, and yet there is still coinsiderable doubt about what ends up being the cause of death. 2 and it's relationship to sleep. 


  I mean there has to be some physical thing that breaks down


To summarize a review/update of the original sleep deprivation study3 :

The effects of total sleep deprivation seem to have interfered with thermoregulation,caused a deterioration in the appearance of the rats, skin lesions, and changes in brain activity; infection, hypothermia and malnutrition are the leading suspects then and the thing that broke down in a roundabout way is the supporting mix of chemicals ( neurotransmitters, hormones) &amp; brain activity that normally keep these deadly effects at bay.

Reference/Sources:



A great and accessible introduction to the science of sleep is The Secret World of Sleep (Lewis). - Sleep and Metabolism: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2929498/ -Sleep and the immune system: https://www.ncbi.nlm.nih.gov/pubmed/12701994/ - Neuroscience (Purves) has a more technical overview. 


Sleep deprivation in the rat: III. Total sleep deprivation. In this 1989 study rats were deprived of sleep and died, no direct cause was found.


Sleep Deprivation in the Rat: An Update of the 1989 Paper Does a great job in presenting the difficulties of a definitive answer, but does give a general one.