In the case of sleep your brain can correlate the time of the alarm to whatever physiological state you are in at that point of sleep, which can create a strong

In the case of sleep your brain can correlate the time of the alarm to whatever physiological state you are in at that point of sleep, which can create a strong associative effect. You could call it keeping track of time though it sounds more like keeping track of a point in time than keeping track of a duration. I have the same relationship to my alarm clock.