Comment by seer

You might need stronger environmental queues for your body to wake up. The body has both internal and external data to know when you have to wake up - lights, noise levels etc.

If you set up your bedroom “too well” - quiet, light blocking roller blinds etc, then your body can only rely on the internal clock.

I used to have that but since moving to another place without those “niceties” suddenly my body quite easily finds “the correct time” every day.

Also you can experiment with this on long flights to get rid of jet lag. After I land, if I spend the first night drinking and fall asleep, I effectively ruin my internal clock for the night, and then the body has only the environmental queues. Wake up in the morning and my clock is effectively reset. Might not feel great for the day but suffer zero jet lag as I start waking up in the morning at the “correct” time even though I’ve flown halfway across the planet.