They already make deaf alarm clocks for this. I actually use to use one for overnight alerts because I'm a heavy sleeper and I don't want to wake up my wife with my phone sounds.
This was one of the things I liked about my fitbit, the vibrate alarm was more than enough for me since I'm a super light sleeper, and I can get woken up without waking up my gf. In fact, her fitbit vibrate would wake me up but not her but she's the one wearing it.
Works pretty well on Apple Watch as well.
I went to RIT; the constant BZZZRRRT BZZZRRRT BZZZRRRT of deaf alarm clocks going off in several dorms at all hours of the day just became a part of life.
Same here, it has the ability to control the intensity and pitch of the tone, a unit to shake the bed, and the ability to flash a lamp of your choice. The lamp or the bed shaker is usually the way to go with someone else present, definitely.