Quote:
I was at the end of a REM cycle,

That's also a possible explanation as to why you failed. That's not your fault, though; that's luck.
If I was at the end of a REM cycle, would I still have gone into SP and heard the HI?

Thanks. I am going to try in the morning. I set my watch to beep every hour. I have tried that before, and it usually wakes me up. So I practised laying down and having it beep every few minutes, and then not moving when it beeps and thinking, "don't move..,". So hopefull that will work