In fact, physical torture is primarily used to obtain confessions, like in Vietnam, where pilots were routinely tortured to solicit confessions. Although very few pilots believed that they committed war-crimes, many confessed to them. People will say
ANYTHING to avoid extreme pain, which makes physical torture an unreasonable means of obtaining reliable information.
When it comes to gaining reasonable intelligence the CIA is a world class organization. Drugs combined with dynamic lighting and hypnosis remain mainstays in their arsenal of information-gathering techniques. This does not mean no physical torture is used by the agency. Indeed, physical torture - like highly-publicized water boarding - is primarily utilized to terrify foreign combatants and leaders. Most media hyped torture is simply a propaganda tool.
In a quest for usable information, however, some physical tactics, like sleep deprivation, are useful for inducing a deep trance. This type trance allows the CIA operative to use less drugs, which yields clearer, more concise communications from the subject.
"It should be emphasized that the covert administration of any drug (stimulant, hypnotic, or hallucinogenic agent) can produce an impact on the individual undergoing the stress of prolonged imprisonment and interrogation which goes beyond merely accelerating the fatigue, disturbed judgment, and other effects of the usual prolonged control pressures. The covertly administered drug can make the prisoner feel that the interrogation is affecting him more than it really is. It may make him feel that the interrogator is more powerful or more prescient than he really is, or that the situation has become more intolerable and inexorable than it is in fact."
https://www.cia.gov/library/center-for-the-study-of-intelligence/kent-csi/vol2no2/html/v02i2a06p_0001.htmA subject can even be led to the conclusion that they are at Saint Peter's Gate, in Heaven, giving their final confession.