I need alarm because I need to keep my sleep schedule in strict time frame.
I often wake up at 5:30 because I slept very well at night. But I stay in bed and waiting for alarm.
If I didn't sleep very well, I could wake up at 6:30, but my alarm triggers at 6:00 and I wake up at 6:01.
In the beginning of my experiments with sleep, I tried to use natural wake up. But my sleep schedule started floating a lot and sleep quality degraded when offset become big.
So I decided to keep strict sleep schedule. It's very balanced. If one night my sleep quality wasn't very good, then next night it's guaranteed that I have good sleep quality. But alarm clock guaranteed that I don't oversleep.
I found "sleep restriction" for the first time here (look at "case illustration" on page 3):
I thought the signal for good sleep was that you didn't need an alarm to wake up? Can you point to those academic articles you've mentioned?