Agree. I'm in bed between 9-10 every night (later than that is an exception), and read a book on my phone as part of my sleep ritual. My phones DnD comes on at 9 so I do not get any alerts while reading. From when I get in bed to read, to when I fall asleep might be 15 minutes depending on how much exercise I did that day.

I set an alarm for 6am, but even without one I'm up between 6-7.

Personally, I think the key for people who have a hard time sleeping is consistency. If someone is trying to go to sleep at 10pm Sunday through Thursday, but then staying up until 2-3am Friday and Saturday it's no wonder they can't get on a schedule.

> will wake up promptly at 4am.

A possible explanation is that you've trained your body to wake at that time -- but it isn't necessarily enough/appropriate sleep.

Wouldn't there be feelings of tiredness or some kind of exhaustion? I generally feel well rested and chipper all day.

Without those feelings of tiredness, how would you know if it's training or your actual internal clock working correctly?

You might very well be a short sleeper.

This. I haven't used an alarm for close to 20 years, though my cycle is closer to 12 to 6.

Well, that doesn't invalidate my point.

The whole thing is to listen to your body, the problem is when people do 12 to 6 with an alarm, while they'd actually sleep form 10 to 7 without external constraints.