I mostly have the habit/ability to sleep exactly 8 hours from whenever I go to bed, regardless of the time of day or time zone, with no alarm clock.
I had much insomnia as a teenager and through age ~24. Even as a child, for who-knows what reason, I would resist sleep. While living alone, and working for myself, I decided to try free running sleep. Within a couple of months my sleep normalized to exactly 8 hours (who knew???), regardless of when I went to bed (which could be as ridiculously late as 6 or 11 am, I might run get a cup of coffee from the corner diner and enjoy a little morning air before going to sleep)
Now, 15 years later, I still tend to sleep exactly 8 hours. It is less reliable because I no longer live alone, and occasionally jet-lag or work excitement will defeat me, but all in all the free sleeping approach makes me very happy. My policy is to only use an alarm when I have a specific appointment which I don't want to miss, and to keep my phones etc. silent while sleeping.
I had much insomnia as a teenager and through age ~24. Even as a child, for who-knows what reason, I would resist sleep. While living alone, and working for myself, I decided to try free running sleep. Within a couple of months my sleep normalized to exactly 8 hours (who knew???), regardless of when I went to bed (which could be as ridiculously late as 6 or 11 am, I might run get a cup of coffee from the corner diner and enjoy a little morning air before going to sleep)
Now, 15 years later, I still tend to sleep exactly 8 hours. It is less reliable because I no longer live alone, and occasionally jet-lag or work excitement will defeat me, but all in all the free sleeping approach makes me very happy. My policy is to only use an alarm when I have a specific appointment which I don't want to miss, and to keep my phones etc. silent while sleeping.