Looks Like Jeff Long Got His Facts Right

My daily facts reported me something that made me think of Jeff Long's The Descent, which was an entertaining but "just-OK" book. The story had an enormous potential and IMHO failed to meet any significant height.

Anyway... In his book, Jeff Long sends a bunch of people very very deep in the earth, to the depths totally unknown by the humanity. Without giving too many spoilers, it suffices to say that those peoples' rhythm of life changes. Well, it turns out that this part was not fiction after all:

In the 60s, French geologist Michael Siffre spent 205 days in darkness in a cave, becoming the person who survived the longest unbroken period of time underground.

Apparently, he spent those 205 dark days in Midnight Cave, in Texas, as part of an experiment sponsored by NASA. The goal was to test whether the human body has a natural time clock. During most of the experiment, Siffre's body adhered to a 24-hour day. However, as the experiment neared its end, Siffre started to live 48 to 50-hour days. During these days, he was alert for 33 to 36 hours before sleeping for 12 to 15 days.

The sad part is that it took Michael Siffre five years to recover from the effects of this dark period. And during the experiment, he suffered from depression, thoughts of suicide, and panic attacks.