According to LaBerge's experiment of eye-moment, theoretically it can only be according to real-time. I have heard of instances where experienced dreamers have dreamt for days, months and in one case, even years at a time, without the standard time-skipping experience which can be common in 'long dreams'. For example, check out the more recent entries in Hyu's Blog. Another dreamer which 'time dilated' quite often (if not nightly) was Hukif.