i missed this when it was posted.
"It is often claimed that Gardner's experiment demonstrated that extreme sleep deprivation has little effect, other than the mood changes associated with tiredness (mood swings, short temper, loss of concentration).[6] This is primarily due to a report by researcher William Dement, who stated that on the tenth day of the experiment, Gardner had been, among other things, able to beat Dement at pinball.
However, Lt. Cmdr. John J. Ross, who monitored his health, reported serious cognitive and behavioral changes. These included moodiness, problems with concentration and short term memory, paranoia, and hallucinations. On the fourth day he had a delusion that he was Paul Lowe winning the Rose Bowl, and that a street sign was a person[citation needed]. On the eleventh day, when he was asked to subtract seven repeatedly, starting with 100, he stopped at 65. When asked why he had stopped, he replied that he had forgotten what he was doing.[1]"