Just want to get peoples thoughts on this situation please as I'm not sure if I'm being unreasonable / a massive grump.
DSS who is 20 lives with us, has done since he was 16/17, he's a good kid in general no real problems, we did have a few issues with pushing boundaries a few years ago with him having house parties whilst we were on holiday / bringing people home in the middle of the night whilst we were asleep but that's in the past now and other than that he causes no issues at all. Apart from....
He's got into the habit of going out every Friday and Saturday night, until 3am-6am every time, I'm a terribly light sleeper and struggle to go back to sleep once I'm woken up. So this means every weekend I'm having horrible broken sleep, which puts me in a foul mood all day. He's not particularly loud when he comes back, I'm just such a light sleeper literally anything will wake me up. I used to wear ear plugs but since having DD (who is 18 months) I obviously can't wear them anymore.
DH would sleep through an earthquake, so none of this affects him at all (worth mentioning here in the only one who does middle of the night and early morning with DD) and when I've discussed it with him he's just not that interested in how it's affecting me. Which is another issue completely. However, I just wanted to know those with adult kids still at home is this acceptable / normal behaviour? I'm in my mid 30's so I do have a vague memory of being 20 and wanting to go out all the time but I'd already moved out by then so my late nights didn't affect anyone... it's really come to a head this weekend as it's the bank holiday so I've had Thursday - Sunday of really bad sleeps. With last night him coming home at 1am then back out at 2.30 to return home at 5, which was just great 
I don't really know what the answer is so any advice would be appreciated! I did consider putting this in the step parenting forum but not sure how relevant it would have been in there really.