Oh the timer beeps every few minutes at first and then the intervals get longer. The idea is that your mind doesn't like to be shocked before the timer goes off so it alerts you. Then when you get into a dream even if you fall asleep it wakes you up to avoid the shock. Except you're in the dream.

That's good that swallowing etc doesn't have a huge effect. I'm gonna play around with how much sleep I get before I try.