If the boat has sufficient overhang, and if the chain pulls through the body of the buoy sometimes you can tie it up short so that it is more likely to stay directly under the bow chock or bow roller. That way the buoy can't slide down the hull of the boat and wake you up. A possible downside to this technique if there is swell or motion that the rumble of the chain through the buoy can transmit into the boat and be every bit as annoying.
We've noticed that the newest park buoys in our area have a much softer surface which would quiet this down considerably.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"