Well, in many authoritarians and totalitarian police states, state security organs have practiced extreme sleep deprivation as a way of breaking people, and som

Well, in many authoritarians and totalitarian police states, state security organs have practiced extreme sleep deprivation as a way of breaking people, and sometimes killing them too. (Also something practiced by more than a few democracies in their uglier moments and aspects). One particular anecdote that I've read described in detail was how during the worst days of the Stalinist Soviet state, the NKVD (predecessor to the KGB but much more brutal and lethal) in its obsession to get signed confessions from arrested prisoners, would put them on what was commonly called the "conveyer belt" Solzhenitsyn described it graphically in his book as a process by which a prisoner would be interrogated in turns by an unbroken chain of well-rested NKVD interrogators whose added-together job was to never once let that victim sleep. This was described as killing many of these people within a month or less even though they were fed and given water (sometimes even by force with tubes down their throats, since the point was breaking them, not killing them directly through starvation or thirst). In some cases there were of course also severe beatings and other tortures that could have easily been partial causes of death, but I remember the author describing cases where victims' hearts would finally stop as they descended into slow madness even if they weren't beaten at all over the course of those sleepless weeks. Extreme sleep deprivation can kill, i'm sure of it.