I don't know if its the light buzz or not, but vibrate is definitely good for a thing called beepilepsy.
I can recall a rather boring move meeting back in the mid 90's. I.T. crew all had those Skytel pagers and we had monitoring sofware on the servers to tell us when something went wrong.
Well -- the boss and I are pretty much snoozing through the meeting when all of a sudden our pagers go off. Both of us bolted upright, looked at the pagers and saw gibberish. Off to the elevator to head down to the computer room And while in there everyones pagers are going off. Uh oh.
Turns out Skytel had a little meltdown that day. Most interesting.