My vampires always hibernate during the day. That way they don't wake up too early. Also, one of my vampires has fitful sleep weakness on level 2, and I thought it would cause daymeres, but it doesn't seem to. So, I suppose that's because I use hibernate instead of sleep.
I don't think it freezes emotions, though. If one of my vampires has, for example, embarrassed moodlet that lasts two hours, it always goes away during hibernation, if she hibernates longer than the two hours.