A migraine is a type of severe headache disorder that can last up to 72 hours, and is often associated with nausea, vomiting, numbness, and sensitivity to light, sound or smell; and, more broadly, sleep disturbances, anxiety, or depression. Most migraine sufferers experience migraine attacks one or twice a month, and almost all sufferers are unable to work or function normally during the attacks. Sufferers are sometimes able to detect incoming migraines before the pain hits, through feelings of aura (strange sensory disturbances) or through other premature neurological symptoms (early nausea or sleep disturbances).