Summary
Brief vertigo triggered by lying back, rolling in bed or looking up suggests benign paroxysmal positional vertigo (BPPV). Confirm the affected canal with positioning tests and offer a matching repositioning manoeuvre. AAO-HNS 2017
Hearing loss, focal neurology or persistent spontaneous vertigo require a separate explanation, even when BPPV coexists. See Imaging indications.
Posterior canal disease is commonest; horizontal, anterior, bilateral and multicanal disease also occur.
More detail
Canalolithiasis produces abnormal endolymph movement when gravity moves the particles. Cupulolithiasis can cause more sustained positional nystagmus.