Νίκος said:
If you are going to sleep at 2am even if you wake up 3 pm the all the time you spent asleep will be almost useless.
Going to bed at late times like this is definitely a bad idea, but what you said is only partly true. The time is not useless in any way, and in some extreme situations this can still work provided you sleep enough. That myth of "sleep before midnight is more valuable" is not true in itself. What is
really valuable is to keep a proper biorhthym, which this saying is hinting at. You can get your sleep successfully during any time of the day, but shifting your biorhythm towards the early morning like this is a harmful thing to do over the long-term.
I know because I did this for several months (1-6am bedtime, and waking up at 11-13). I was fine during this time, but the issues came afterwards once I had to shift this back to normal times. This lead to extreme tiredness during the day and, of course, severe issues with falling asleep at those earlier times. Basically, do not do early bedtimes if it is at all avoidable. In extreme situations it is still an option, but stay aware that it will be difficult to reset it back to normal again afterwards.