Fake mission to Mars leaves astronauts spaced out

I don't understand the problem. In space, particularly in a situation where there isn't much to do, why should schedules stick to an arbitrary 24 hour repetition cycle? If everybody's sleeping about 1/3 of the time, why is it important that their cycles line up precisely?

edit: On the surface of the actual planet, of course there are constraints on what is possible and any joint missions need to be synchronized, but it's also easy to simulate a degree of the normal daytime forcing cycle.

Asking the crew to live on mars time and using standard techniques for shift workers (bright lights and blackout curtains) to help this seems like the obvious approach. Certainly it seems scientifically irresponsible to say the effects "would likely have been much worse had the subjects been required to live on a 24.65-hour day" without testing it.