Individuals who suffer concussion -- the most common type of traumatic brain injury caused by a blow or a fall -- should rest for several days to allow the brain to recover and rebalance itself, says a new study. Rest -- for more than a day -- is critical for allowing the brain to reset neural networks and repair any short-term injury, the study said. Repeated mild concussions with only a day to recover between injuries leads to mounting damage and brain inflammation that remains evident a year after injury, the study elucidated. Concussions and mild head trauma can lead to sustained brain damage, the findings revealed, adding that athletes who play contact sports are much more susceptible to lasting brain damages. "It is good news that the brain can recover from a hit if given enough time to rest and recover. But on the flip side, we find that the brain does not undertake this rebalancing when impacts come too close together," said Mark P Burns, assistant professor at the Georgetown University Medical Center (GUMC), Washington, DC in US The study, published in the American Journal of Pathology, modeled repeated mild head trauma as a means to investigate brain damage that occurs after a sports, military or domestic abuse injury. The researchers developed a mouse model of repetitive, extremely mild concussive impacts conducted while the mouse is anesthetised. They compared the brain's response to a single concussion with an injury received daily for 30 days and one received weekly over 30 weeks. Mice with a single concussion temporarily lost 10-15 percent of the neuronal connections in their brains, with no inflammation or cell death, the researchers said. And with three days of rest, all neuronal connections were restored to normalcy. However, this neuronal response was not seen in mice that suffered daily concussions, but the pattern was restored when a week of rest was provided between each concussion, the study revealed. When a mild concussion occurred each day for a month, it also resulted in inflammation and damage to the brain's white matter. And this damage worsened progressively for two months and remained apparent even one year after the last concussion, the researchers concluded.