The earliest manifestation of increased intrcranial pressure following head injury is

In general, symptoms and signs that suggest a rise in ICP include altered level of consciousness, headache, vomitingwithout nausea, ocular palcies, back pain and papilledema. If papilledema is protracted, it may lead to visual disturbances, optic atrophy, and eventually blindness. The headache is classically a morning headache which may wake them from sleep. The brain is relatively poorly supplied by oxygen as a result of mild hypoventilation during the sleeping hours and also cerebral edema may worsen during the night due to the lying position. ref-Graham, D. I.; Gennarelli, T. A. (2000). "Pathology of Brain Damage After Head Injury". In Cooper, Paul Richard; Golfinos, John (eds.). Head Injury (4th ed.). McGraw-Hill. pp. 133-54