my housemate uses the vibrating ones. it goes off @ 4am, and i can hear it from the other side of the house. I can hear this low rumble throughout, and it shakes the garage door opening motor lol.
I have 5 alarm clocks going all off at different intervals, all placed in different places around the room. I literally cannot hear them clearly... It's like this distant, muffled sound and it takes them about 1 hour the annoying noises to finally register in my head, and i wake up. I hate how i can never wake up.
Wierd thing is, a human being can wake me up instantly. I can wake up before the alarm clock, or even wake up very easily on time when I am sleeping not at home (hotel, someone else's house, etc...). Just that when I am in my own bed, I have problems.
I get on avg 7-8 hours nightly. What sucks is that when I am left untouched to sleep through, I last about 10 hours avg.