Passage: Following Stoltz's departure, Fox's schedule during weekdays consisted of filming Family Ties during the day, and Back to the Future from 6:30 pm to 2:30 am. He averaged five hours of sleep each night. During Fridays, he shot from 10 pm to 6 or 7 am, and then moved on to film exterior scenes throughout the weekend, as only then was he available during daytime hours. Fox found it exhausting, but "it was my dream to be in the film and television business, although I didn't know I'd be in them simultaneously. It was just this weird ride and I got on." Zemeckis concurred, dubbing Back to the Future "the film that would not wrap". He recalled that because they shot night after night, he was always "half asleep" and the "fattest, most out-of-shape and sick I ever was".

Question: days did it happen?
Fridays