A typical symptom of benign paroxysmal positional vertigo (BPPV) is a very intense but short-lived dizziness that occurs when changing the position of the head (when lying down in bed, for example). This type of vertigo frequently causes falls.
BPPV is caused by crystals in the inner ear, called otoliths, that break off and circulate in fluid from the ear canals. These canals are used to detect rotational movements of the head. The presence of crystals creates a much faster movement of the liquid and makes the brain feel like you have just spun around at high speed.
Benign paroxysmal positional vertigo is more common in older people, but can occur at any age, especially after a fall or impact to the head.