With the exception of "Can't miss, must catch International Flights to Australia" and one "Stayed out late drinking and have to give a major customer presentation in a strange city in precisely 4 1/2 hours" - I haven't used an alarm in 6 years. There are a lot of people, particularly after you turn 30, that basically wake up after 6 or 7 hours of sleep, and, as long as you went to bed with a personal mandate to be somewhere at a particular time, have relatively little difficulty getting up.

This is very, very, very different from when I was younger, when _every morning_ waking up was like some sleep deprivation torture - it physically hurt to get up, and I would have done everything to get a bit more sleep.

I used to fantasize about how wonderful it would have been to go to sleep in my school classroom, and then just wake up and start working.

And then I went to work at Netscape in 1996, 25% of the people had little sleeping bags and mattresses under their desk - and yes, it was wonderful. :-)

I would bet most do on a normal day, and nearly all do when they have to wake up at 3:30am after going to sleep at 2am.

If a person or alarm doesn't wake me up, I often will not wake up naturally. At all. One time I went to bed at midnight on Friday and didn't wake up until Monday morning at 1 am. Waking up for me feels like coming up from being deep under water in a lake. Sometimes the lake is frozen over: when the alarm is going off I get close to enough to waking be aware but get trapped under the "ice" and can't make the transition fully out of sleep.

Conversely I have great difficulty falling asleep before 3 am. My diurnal cycle isn't just late, it is 100% reversed: daylight makes me sleepy and darkness keeps.me awake.

I had a sleep study and they said I do not have narcolepsy because I took 11 minutes to enter REM sleep and the cutoff for diagnosis is 10 minutes. However, they also expect you to "sleep" between 8pm and 4am for the study. Wtf? I'd like to see the doctors who think that constitues a reasonable time for a study try sleeping at mid afternoon, see if they can sleep normally that far outside their cycle times.

Left to my own devices I would wake up only when I get hungry for lunch.

I have to say I ditched my daily wake up alarm 10 years ago and I've been much happier since. I used to wake up annoyed every day because of the alarm--It is such a significant difference in life to not wake up grumpy every single day.

Now I only set an alarm if I have a very special early morning appointment.

Not day-to-day but whenever I have a morning meeting that I might not wake up for or--alas more commonly--an early morning flight. If it's important and especially if it's very early, I set 2 alarms, one of which isn't "roll over and hit off" distance from the bed. I agree with those that don't depend on their phone's alarm for anything that's critical. When traveling I'll always use either the room alarm or the wakeup service if I have to get up early for something important.

I think most people do, not needing one is rather unusual, though presumably quite nice.

All of us with sleep apnea do.