Early to bed

Ever since I can remember my "schedule" has always been early to bed (around 8 pm), early to wake up(around 6 am). Which i never questioned because thats a typical routine for a little kid.

As a result of this, i could never physically stay up late when i was younger because i would wake up early the next morning, just from my body being so used to it, and would wake up with a headache, nausea, and usually would end up throwing up until i got more sleep. ("Late" being anytime after midnight)

Now i still have this problem and im almost 18 years old, which i dont find normal because all my friends are able to stay up as late as they want and even pull all-nighters with no problems. It's not quite as bad as when i was younger but i still dont like being out past midnight because it just messes my whole sleeping schedule up, and me having insomnia makes me need to keep a set bedtime routine.

Is this normal to be this age and still have a problem with being out/up late? I've only heard of this problem in really young kids and most older adults wanting to be in bed at a certain time.