The report describes extensive waterboarding as a “series of near drownings” and suggests that more prisoners were subjected to waterboarding than the three prisoners the C.I.A. has acknowledged in the past. The report also describes detainees being subjected to sleep deprivation for up to a week, medically unnecessary “rectal feeding” and death threats. Conditions at one prison, described by a clandestine officer as a “dungeon,” were blamed for the death of a detainee, and the harsh techniques were described as leading to “psychological and behavioral issues, including hallucinations, paranoia, insomnia, and attempts at self-harm and self-mutilation.”