I never knew it had a name. Anyone ever have this happen:
In the phenomenon known as an auditory sleep start, waking from sleep is accompanied with a very loud snap or cracking which seems to come from the center of the head. Some people have also been known to have visual sleep starts, in which a blinding flash of light awakens the sleeper, but these cases are also extremely rare.
When I lived in an apartment, it happened a few times I woke up from a dead sleep to get up and answer the intercom, but it never really rang. Those occurrences really left me messed up.