It's an interesting read but I kept finding myself questioning the conclusions that were drawn. I always assumed it was that phenomenon where we're seeing a false pattern in randomness. If I'm reading things right, here, the article cites a study that basically involved calling people and asking them if they wake up before their alarm clock regularly -- I'm hoping they've accounted for this.

The thing I'm talking about (it has a name that escapes me and Google was no help) was something that affected my ex-wife a lot. She felt like she saw her birthday (US format) on the clock all the time. Upon further examination, her birthday lands near a mealtime (when she's more likely to look at the clock) and being that one arbitrary combination of numbers has significant meaning, every time she looks at the clock around meal-time, daily, she has about a 1 in 20 shot of really noticing the time, but were it -- say -- 12:05, she wouldn't make a mental note of it (or may not even remember looking at the clock).

Similarly with time "just before the alarm goes off", you wake up several times throughout the night and sleep lighter in the morning. You're really going to notice the time if the alarm is going to go off in 5 minutes vs. say 45 minutes. You're also far more likely to look at the time if it's starting to get light outside, if the birds are chirping, or there's other subtle signs of morning approaching whereas when you awake and it's obviously night you are less likely to bother checking the time.

I don't think they investigated their survey questions correctly and missed the obvious. I'm not among the 25% who reliably wake up without an alarm, at times I was very far from it being horribly late at least once a week, yet I know from past situations that I can will myself to awake at any particular time, occasionally waking up an hour early (particularly if there is a high stress reason) but more often within 10 minutes of the goal. But there must be a reasonable motivation that I haven't killed by doing it every day for a routine I don't really enjoy.