I have this problem with our 14 year old. In the holidays he loves to stay up all night, drinks loads of coffee etc. plays his computer game, watches films or whatever. In the past we have had problems with mild depression and bad behaviour so I have said he can't do this and banned anything with caffeine until he has his sleep patterns back to normal.
I do believe you should never wake a sleeping teenager, but is this common? He sleeps all day which means he gets no fresh air or social life. He has plenty of friends but seems to really like this time on his own.