Your far ancestors didn't have to deal with light pollution and all sorts of city lights. I don't know where you live, but a lot of people live in cities, where this is a problem. If you live in the countryside or in very small cities, you may not have the same problem.

Our ancestors used to go to bed earlier and wake up in the middle of the night for a while before going back to sleep. Our schedules and concept of 'normal' (versus 'natural') has changed drastically.

For more info on the two sleeps:

The forgotten medieval habit of 'two sleeps' -- https://www.bbc.com/future/article/20220107-the-lost-medieva... and the HN post: https://news.ycombinator.com/item?id=29886907

And Wikipedia: https://en.wikipedia.org/wiki/Biphasic_and_polyphasic_sleep

Street lights are too bright for sleep where I live, and I need to wake up with an alarm anyway so no waking up with the sun for me. It's a no brainer!

I set up an automation to slowly open my curtains when I want to wake up. It's a much nicer way to wake up than an alarm.

Yeah, as other commenters have said - the curtains are for bright city lights I can't turn off.

Personally, I have a simple electrical timer set to turn on a bright sunlight bulb at 6:30am, and I open the curtains during the day.

You're right on the money about camping and how it affects the body, in my experience. Light obviously isn't the only factor in camping feeling good - but I've also been reading lately that light exposure (and possibly direct sun exposure?) during the day is quite good for you.

Probably the fact that you’re breathing more oxygen when asleep while camping, vs a high CO2 level in your home bedroom.

I use a Philips wake-up light for that.

> Why is it that when you go camping you feel so refreshed and good when the sun comes up and wakes you up?

Because alcohol induces REM sleep?

It actually reduces REM sleep:

https://www.albertahealthservices.ca/assets/info/amh/if-amh-...

It can both induce REM, and reduce the length of total REM, yes.

The worst sleep I ever get is when I drink alcohol too close to bedtime.