Brain Zapped

[theri]

    Before i run off and spend some huge amount of cash on medical tests, i
was wondering if anyone had heard of this...
    For the last couple of years as i'm going to sleep, and i'm at that
place betwen awake and sleep i get a profound sense of vertigo thats joined
with what's in my head is an audible bang or zap, and in my mind's eye i see
a very bright yellowish flash. It may happen one to five times a night and
it only happens as i'm about to go to sleep.
    If this is the wrong forum to ask in, please direct me to a more
appropriate newsgroup/location :).
    Thank you all,
    theri (asking on a friend's behalf)