What is Torture?
Sleep deprivation can be a form of torture. It all depends of the definition. Usually its described by total sleep allowed per day and length of continuous sleep. Letting a prisoner sleep for 12 hours a day is meaningless if you wake them up every 15 minutes.
Maybe this needs another post but it is pointless to argue about the definition of torture if there is no agreement on its effectiveness.
Is Torture Ever Necessary?
Is torture effective? Yes. Be clear, by saying its effective all we're admitting is that an effect was achieved. Whether it was the desired effect, that is an entirely different matter. While torture may be effective, neither is it efficient, nor is it efficacious.
(Courtesy of Wikipedia)
The word effective is sometimes used in a quantitative way, "being very or not much effective". However it does not inform on the direction (positive or negative) and the comparison to a standard of the given effect. Efficacy, on the other hand, is the ability to produce a desired amount of the desired effect, or success in achieving a given goal. Contrary to efficiency, the focus of efficacy is the achievement as such, not the resources spent in achieving the desired effect. Therefore, what is effective is not necessarily efficacious, and what is efficacious is not necessarily efficient.