I can sense when it’s time to wake up, while asleep. It’s likely just confirmation bias, but I almost always wake up minutes before my alarm if I have a stressful or unusual appointment, like an early flight or interview. I assume most people has this with their routine wake-up time, that the body learns when to wake up right on time… but this is like: if I usually wake up at 8:30 but now have to wake up 5:45 or 6:15 or whatever, I’ll wake up on my own right before the alarm goes off. I just need to think about it somewhat thoroughly (wake-up time and approx. how many hour of sleep until then) before falling asleep.