Though the detainee's name and critical details are blacked out in the memos, there is only one detainee known to have been in CIA custody at that time: Mohammed Rahim al-Afghani, an alleged al-Qaida operator and translator for Osama bin Laden.
The documents show that even as the Bush administration was scaling back its use of severe interrogation techniques, the CIA was still pushing the boundaries of what the administration's own legal counsel considered acceptable treatment.
The documents describe two instances in 2007 in which the CIA was allowed to exceed the guidelines set by Bush administration lawyers allowing prisoners to be kept awake for up to four days.
The first episode occurred in August 2007, when interrogators were given permission from the Office of Legal Counsel to keep an unidentified detainee awake for five days, a U.S. government official confirmed. The official spoke on condition of anonymity because he was not authorized to discuss the report's details.
According to the documents, the sleep-deprived prisoner was kept awake by being forced to stand with his arms chained above heart level. He wore diapers, allowing interrogators to keep him chained continuously without bathroom breaks.
The second incident occurred in November 2007. After again asking permission from Justice lawyers to keep a detainee awake an extra day, interrogators pressed to extend the treatment for another 24 hours, depriving the prisoner of sleep for six straight days.
It is unclear from the documents whether the two incidents involved the same detainee. CIA spokesman George Little would not provide the identity of the prisoner referred to in the document.
Afghani, the alleged bin Laden translator, was captured in Pakistan in the summer of 2007 - around the time the Justice Department issued new guidance for the harsh techniques that could still be used on CIA prisoners. He stayed in CIA custody until early 2008, when he was transferred to the military detention facility at Guantanamo Bay, Cuba.
Officials noted in the documents that the sleepless prisoner remained "alert and oriented" and seemed to be "adhering to a well-developed, robust and capable resistance strategy."
According to the documents, the prisoner was monitored by closed-circuit television. If he started to fall asleep, the chains jerking on his arms would wake him up. If a prisoner's leg swelled - a condition known as edema, which can cause blood clots and stroke - interrogators could chain him to a low, unbalanced stool or on the floor with arms outstretched.
Sleep deprivation beyond 48 hours is known to produce hallucinations. It can reduce resistance to pain, and it makes people suggestible.
The State Department regularly lists sleep deprivation as a form of torture in its annual report on human rights abuses. Recent reports have noted Iran, Syria and Indonesia as engaging in the practice.
Andrea Northwood, director of client services at the Center for Victims of Torture in Minneapolis, said her organization considers 96 hours of sleep deprivation to be torture.
"It's a primary method that is used around the world because it is effective in breaking people. It is effective because it induces severe harm," she said. "It causes people to feel absolutely crazy."
She said that in many cases there are lingering effects. "My experience in working with survivors, they are still struggling with questions whether they are normal, whether they should have acted as they did when they talked under this kind of pressure," she said.
Amrit Singh, a staff attorney with the American Civil Liberties Union, said the use of such a severe tactic in 2007 shows that the U.S. was not abiding by its own law.
"The documents are particularly disturbing because they were issued even after the Supreme Court held that these prisoners were entitled to the protections of the Geneva Conventions and after Congress passed the Detainee Treatment Act to specifically prohibit cruel, inhuman and degrading treatment," Singh said.
Before scaling back its "enhanced interrogation program," the CIA used 10 harsh methods, including waterboarding, a form of simulated drowning. It later used six techniques, including sleep deprivation, dietary manipulation and slapping.
The Obama administration has since rescinded authority for any of the severe methods. Under the rules of the U.S. Army Field Manual, which now governs all interrogations, prisoners must be allowed to sleep at least four hours during every 24-hour period.
Associated Press writer Matt Apuzzo contributed to this report.