I've had enough of waking up and switching off my alarm clock subconsciously; then waking up again half an hour later and having to rush out to school.  So I have purchased an FSR which I plan to mount under the mattress on my bed.  Then by adding a small circuit board and do a bit of fiddling I should be able to make the alarm clock switch off only when I'm out of bed.  However the surface mount board is making things tricky at the minute.