Awakening a minute or so before the alarm is a common experience and I, like many people, have learned the trick of setting such an 鈥渋nternal alarm鈥�. Biochemical clocks and circadian rhythms hardly seem to explain how a mental clock could be so accurate. What is happening?
鈥� I also wake a few seconds before my alarm clock rings. The reason is the cue that triggers awakening. One simple answer is that the cam and pawl that triggers the alarm in a mechanical alarm clock produces clicks or pops that alert the sleeper before the actual sounding of the alarm. My clock certainly does this.
Another answer is that there are other trigger-cues, most likely aural ones, that occur at the same time each day and that the sleeper reacts to. It might be a noise produced by a central heating system controlled by a timer or even a passing delivery van.
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Jim Field, Aberystwyth, Dyfed, UK
鈥淥ne answer is that there are aural trigger-cues which occur at the same time each day and that the sleeper reacts to before the actual鈥�
鈥� I too have been impressed by the accuracy of my mental clock, awakening me regularly a minute before my alarm went off. Then I noticed that a minute before the daily alarm sounded each morning, my electronic alarm clock clicked.
During the day the click is practically inaudible, due to considerable background noise, but in the quieter mornings it is easily loud and clear enough to wake me up. So in my case good hearing and not an accurate internal alarm explains the seemingly inexplicable.
Radko Osredkar, Ljubljana, Slovenia