The duration of coma varies with different degrees of cerebral contusions, with typical cerebral contusions generally lasting more than half an hour, while more serious patients can be in a coma for hours, days or even months without signs of wakefulness. Coma is a disorder of consciousness, which can indirectly indicate head injury. Patients often wake up with headache, dizziness, nausea, vomiting and other symptoms that require prompt medical attention.