DS napping after school

[Dizzydials]

DS is 15 and at least three times a week falls asleep straight after dinner.
DS leaves for school at 7.15 and gets home around 5.
DS does find school exhausting but the naps don’t usually start until towards the end of term, this school year he’s been sleepy from the start.

Is it worth mentioning to the GP or just leaving him to it?

How long does he nap for and how long does he sleep at night? Is he on the internet or gaming when he should be asleep ?

I was like this as a teen, loved coming home and getting in bed until dinner! Sometimes I used to spend all day Saturday in bed snoozing. I worked part time and went to 6th form. Usually went out on a Saturday night. I don't have any health problems that caused it, I just loved my bed. TBH I wish I could still do this after work!
If you're worried it might be worth a trip to the doctors, but I think it's within the realms of normal. There's lots of illness around at the moment. Has he been poorly? My children and DH all had a bad cold a few weeks ago and one of my DC is still really tired and not getting up as early as usual.

Usually 2-3 hours, then falls asleep around 11 for the night.
Last night he was asleep at 6.30 and didn’t wake until this morning. He was shocked it was Wednesday!