[Gayle]

I watched a programme a few years ago and a girl was put into a room with no means of telling the time. She lived in there for a month and slept and woke when it was natural. The scientists who were monitoring her made sure that she had no way of knowing what time it was by changing their shifts and so on. At the end of the month the scientists told her it was time to come out but she thought it was only day 23. Within a few days of going into the room her body clock had changed to a 36 hour day instead of a 24 hour one.