To uncover what is covered; the sacred mission of all scientists! Such a mission is, naturally, best performed at night. Therefore, the research progress is counted every Midnight. Whatever the Brainers were doing at that moment, they will be stuck with it for the rest of the night, whether at their workplace or otherwise. And what do they do during the daytime? I guess sleeping! All the most innovative ideas come when you sleep! During the day, you can switch them from project to project freely, but it doesn't mean they will appear there before the Midnight comes again...