Flies buzz about.

Another interrogation method was the stoika. It consisted of standing a prisoner against a wall on tiptoe and making him hold that position for several hours. A day or two of this was said to be enough to break almost anyone.
....

When there was time, the basic NKVD method for obtaining confessions and breaking the accused man was the "conveyor" -- continual interrogation by relays of police for hours and days on end. As with many phenomena of the Stalin period, it has the advantage that it could not easily be condemned by any simple principle. Clearly, it amounted to unfair pressure after a certain time and to actual physical torture later still, but when? No absolutely precise answer could ever be given.

But at any rate, after even twelve hours, it is extremely uncomfortable. After a day, it becomes very hard. And after two or three days, the victim is actually physically poisoned by fatigue. It was "as painful as any torture." In fact, we are told, though some prisoners had been known to resist torture, it was almost unheard of for the conveyor not to succeed if kept up long enough. One week is reported as enough to break almost anybody....

There is nothing new about the conveyor method. It was used on witches in Scotland. The philosopher Campanella, who withstood all other tortures in the sixteenth century, succumbed to lack of sleep. Hallucinations occur. Flies buzz about. Smoke seems to rise before the prisoner's eyes, and so on.

-- Robert Conquest, The Great Terror: A Reassessment.

... Compare:

Sgt. Ben Allbright knows something about sleep deprivation. During the first six months of the Iraq war, his job was to guard prisoners in Al Qaim, a makeshift base near the Syrian border where U.S. troops conducted aggressive hunts for Saddam Hussein's weapons of mass destruction. Every day, soldiers hauled in about 20 new detainees for questioning by military interrogators or CIA operatives. To "get them out of their comfort zone" before the interrogation, Allbright told Newsweek recently, the drill was to keep the Iraqis awake for 24 hours or longer. The guards would stand the prisoners up in old shipping containers, their hands tied behind their backs and their faces blindfolded and facing the wall. "After a while you'd see their knees buckling, or you'd see one of them lean forward and put his forehead against the wall to try to sleep." When that happened, Allbright would holler into the container or bang on the metal side with a stone or a club.

... Human Rights Watch, which interviewed the lawyers of 20 detainees held in a secret [CIA] prison in Afghanistan as late as 2004, says some of them were sleep-deprived for up to two weeks, though sometimes allowed short naps. The facility, known among detainees as "the dark prison," was among the harshest run by the United States since the start of the war on terror.

-- Dan Ephron, "Singing for Your Sleep: President Bush Aimed to Clarify Interrogation Rules: So Is It Legal -- or Effective -- to Deny Prisoners Rest?", Newsweek, Oct. 30, 2006.

Divulging state secrets

There are many accounts of the NKVD insisting that anyone released (usually after 1938) should sign a guarantee not to reveal what had happened to him in jail. A Soviet newspaper recently quoted one such:

I, Sternin, N.V., pledge never and nowhere to speak of what became known to me between 11 June 1938 and 11 July 1939 about the work of the organs of the NKVD. It is known to me that on any breach of this I will be accountable under the strictest revolutionary laws, for divulging state secrets.

-- Robert Conquest, The Great Terror: A Reassessment.

... Compare:

The Bush administration has told a federal judge that terrorism suspects held in secret CIA prisons should not be allowed to reveal details of the "alternative interrogation methods" that their captors used to get them to talk.

The government says in new court filings that those interrogation methods are now among the nation's most sensitive national security secrets and that their release -- even to the detainees' own attorneys -- "could reasonably be expected to cause extremely grave damage." Terrorists could use the information to train in counter-interrogation techniques and foil government efforts to elicit information about their methods and plots, according to government documents submitted to U.S. District Judge Reggie B. Walton on Oct. 26.

-- Carol D. Leonnig & Eric Rich, "U.S. Seeks Silence on CIA Prisons: Court Is Asked to Bar Detainees from Talking About Interrogations," Washington Post, Nov. 4, 2006.

The Party can do anything

The exact methods by which Stalin silenced her [Krupskaya] are unknown. He is said to have once remarked that if she did not stop criticizing him, the Party would proclaim that not she, but the Old Bolshevik Elena Stasova, was Lenin's widow: "Yes," he added sternly, "the Party can do anything!"

-- Robert Conquest, The Great Terror: A Reassessment.