I wake up about 5 minutes before I wish to wake up. After doing this a few months I stopped setting the alarm and continued to wake up on time. I think it is l

I wake up about 5 minutes before I wish to wake up. After doing this a few months I stopped setting the alarm and continued to wake up on time. I think it is likely related to training against other criteria: birds, sunrise, cars ... etc. since a change in location will throw off my timing and require a few weeks to learn the new 'time'. Zen alarm clocks are awesome btw, http://www.now-zen.com/ http://www.now-zen.com/. I love mine and used it extensively when I was a student. The alarm is sounds beautiful and seems to week. The association of a particular bell sound with the requirement of waking is powerful. After using the alarm for a few weeks I no longer would remember hearing it but feel compelled to get up and disable the alarm before it could ring again!