five o'clock mark


In the documentary 21 up, a girl said "It's a funny day actually, because I suppose I was up somewhere around the five o'clock mark and I spent all day preparing, well all morning I should say and then sitting around for about three hours. Just waiting for something to happen then when it did happen I don't remember it." What does "five o'clock mark" mean? Thanks.
  • entangledbank

    Senior Member
    English - South-East England
    It's not a normal way of saying the time, though. 'Mark' is sometimes used with measurements where you imagine stages marked off: in a race there might really be a mark at the 500 m point, or you might just say you got tired around the 500 m mark, as if there was. Radiation becomes too red to see at about the 700 nm mark.