I would suggest reading as much as you can about BPPV to see if the symptoms match your own. Vertigo at night can accompany both MD and other inner ear disorders as well as BPPV, but the main difference is that with BPPV the attacks of short bursts of vertigo are almost always motion connected whereas with something like MD they are spontaneous, ie they may start when movement initiates them but then the full-blown attack develops and persists. With BPPV the attack is short and dies away within a few minutes, after the person has moved the head or gone from lying to sitting or vice-versa. For more info see
"The symptoms of BPPV include dizziness or vertigo, lightheadedness, imbalance, and nausea. Activities which bring on symptoms will vary among persons, but symptoms are almost always precipitated by a change of position of the head with respect to gravity. Getting out of bed or rolling over in bed are common "problem" motions . Because people with BPPV often feel dizzy and unsteady when they tip their heads back to look up, sometimes BPPV is called "top shelf vertigo." Women with BPPV may find that the use of shampoo bowls in beauty parlors brings on symptoms. An intermittent pattern is common. BPPV may be present for a few weeks, then stop, then come back again."