This guy is over-thinking it. And underestimating the human brain.
So, you just trained yourself to wake on time, at 0657 or whatever time shortly before 0700 you thought wise - after all, you didn’t want to be early, as then you’d just stand in a freezing corridor, and you’d have wasted precious minutes of sleep. Eighth was the perfect place in line, as that was how many shower heads there were. I digress...
To this day, I have zero need for an alarm clock - I just pick the time I want to wake at, and I do, within a minute. I can decide to have a 15 minute nap and it’s exactly that. If I don’t set a constraint, I sleep on until I “naturally” wake up.
I have absolutely no idea how this unconscious dead reckoning of time works, but it does. I’m not as good at it awake as I am asleep - I only manage ten minute accuracy.
Another plus is that you don’t get sleep inertia like you do when woken by something suddenly, and instead wake up, well, awake.
Are you getting restful sleep?
I can manage to do something like this within a 10-30 minute range where I’m lying in bed kind of half awake until I decide to just get up, or my alarm goes off and I hit it instantly and I’m ready to go. But I’ve come to realize that it’s not some super human time keeping ability—I’m basically staying up all night, not actually sleeping, anticipating the time I need to get up, and my mind just forgets all but the past few minutes.
I realized how I did it after I started taking naps at work. If I can get at least 20 uninterrupted minutes, I basically blink and wake up rested. If someone walks by or there’s a noise at some point during that period, it’s basically me just groggily sitting around for half an hour and then my memory of it all fades a bit after the break finishes and I forget I was basically awake the whole time.
Adapting to a schedule and waking up at the right time is one thing. Being able to arbitrarily set a time sounds either superhuman or like there’s no truly deep sleep occurring.
Oddly, i wake up almost always 2 minutes before my alarm. self preservation is a hell of an instinct.
I have, many times, with many different alarm clocks or phones, woken up a minute or so before the alarm is set to go off, and usually I unset the alarm and get out of bed. There's no prep noise, no early warning, no re-imagining how things happened. I just do it, sometimes.
The answer isn't that I have a clock in my brain, but rather that waking phases occur regularly during sleep. I start to wake up, think "what time is it?" and check my phone. If it's within 30 minutes of my alarm, I just turn my alarm off and get up.
No magic required.
To do it blindly you can have someone else do it, scramble the clock, use an app,...
I had trained myself to fall asleep immediately after falling on bed and waking exactly at 6 without setting an alarm.
I don't think it's magic. There are plenty of cues (sound and light) that can tell you approximately what time it is without being conscious.
Interesting hypothesis but so easy to disprove.