Yup. I grew up in dorms at boarding school. The art was to wake up five minutes before the bell, so you could be first in line for the showers and get hot water, and then to breakfast before they ran out of the good choice. You couldn’t have an audible alarm, as you’d wake others and then you’d have competition.

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.

> 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.

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.

The book Why We Sleep discusses the phase of our sleep that has extremely accurate timekeeping. I've forgotten the details, of course. But I think it's quite clear our brains know precisely what time it is.

A book on sleep (and more) that deserves to be much more widely known is The Head Trip by Jeff Warren:

https://www.goodreads.com/book/show/2168851.Head_Trip

i wake up before my alarm goes off in order to not wake my wife. if my alarm goes off and wakes her before her alarm then a "whopping" is an understatement of what follows hah.

Oddly, i wake up almost always 2 minutes before my alarm. self preservation is a hell of an instinct.

You reminded, my times at boarding school.

Yeah, it's not a cognition re-ordering event that's happening. You simply wake up just before the alarm because the human brain be crazy, yo.

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.

Strange to say but I actually don't mind being woken up due to someone else's alarm. It lets me experience the pleasure of knowing I get to go back to sleep :)

Mine sounded like a foghorn...

The author is not necessarily wrong about his case, and this could be investigated experimentally - have someone else set the alarm to a time he does not know.

Though I don't have the common room experience that you had, I too regularly wake before my alarm goes off with more than enough time to turn it off.

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.

That's a reasonable scenario. But not the one I experienced. My history is of waking up seconds before the required time.

For what it's worth, I have the same experience as you. I wake up, once, maybe a minute before the alarm is supposed to go off. And I'm immediately clearly awake, not groggy, not sleepy, no gradual slow awakening.

Can confirm. I wake up and disable my alarm before it goes off all the time. I think the brain just has an accurate timer.

It should be easy to test. Just set the alarm at a random time. Something like 5 to 10 minutes earlier.

To do it blindly you can have someone else do it, scramble the clock, use an app,...

In my experience, it only works if I know the time and want to wake up at that time. I'm more likely to experience it the more important it is that I wake up on time. If I have to wake up for travel purposes, it's almost guaranteed that I'll wake up before the alarm.

Please read the book "power of subconscious mind".

I had trained myself to fall asleep immediately after falling on bed and waking exactly at 6 without setting an alarm.

When I was young, I would prepare to wake up before the alarm if I really wanted to make sure I didn't oversleep. I would stare at the current time for about a minute and then go to sleep. The next day I would always wake up a few minutes before the 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.

I often wake up before an alarm even when I've not set it, or it's set to silent. Actually I rarely set an alarm but usually wake up +/- 5 minutes of the same time.

Interesting hypothesis but so easy to disprove.