[m-i-l]

> "I am curious how much our body clock synchronizes with real time"

Various experiments have been performed with people in caves, where they don't have "time cues" such as natural daylight. From the Michel Siffre wikipedia entry[0]: "He found that without time cues, several people including himself adjusted to a 48-hour rather than a 24-hour cycle ... Several astronauts reported experiences similar to those experienced in underground experiments such as loss of short-term memory to being isolated from external time references." And for Stefania Follini[1]: "her biological clock drifted away from its regular rhythm to following first a 28-hour day, and later on a 48-hour one ... When she finally emerged from the cave at the experiment's end ... she estimated that it was ... only two months from the start of the experiment instead of the four that had actually transpired".

[0] https://en.wikipedia.org/wiki/Michel_Siffre

[1] https://en.wikipedia.org/wiki/Stefania_Follini