Helmet to reduce traumatic brain injuries

A protective helmet includes a plurality of fluid filled bladders, impact sensors, valves, and pumps wherein the helmet absorbs energy from an impact to protect a person wearing the helmet from traumatic brain injury. The bladders expel fluid in response to a triggering event such as energy from an impact detected as a pressure spike event and/or detected as an acceleration event. A selected bladder may expel fluid to other bladders, to a reservoir, to the environment outside of the protective helmet, or combinations thereof. In embodiments where the bladders need additional fluid after an impact, one or more pumps may refill selected deflated bladders. When a bladder is underinflated, an indicator light may emit light on an outer surface of the protective helmet to warn that the bladder is not yet ready to be placed in operation to absorb another impact.