" It’s a point well illustrated by Michel Siffre, a French chronobiologist (he studies the relationship between time and living organisms) who conducted one of the most extraordinary acts of self-experimentation in the history of science. In 1962, Siffre spent two months living in total isolation in a subterranean cave, without access to clock, calendar, or sun. Sleeping and eating only when his body told him to, he sought to discover how the natural rhythms of human life would be affected by living “beyond time.” Very quickly Siffre’s memory deteriorated. In the dreary darkness, his days melded into one another and became one continuous, indistinguishable blob. Since there was nobody to talk to, and not much to do, there was nothing novel to impress itself upon his memory. "
― Joshua Foer , Moonwalking with Einstein: The Art and Science of Remembering Everything