This video explores the science behind concussions, explaining how the brain is affected by impacts and the resulting symptoms. It discusses the importance of rest for recovery and dispels myths about sleeping after a concussion. The video also highlights the potential for post-concussion syndrome and the risks of returning to activities too soon.

Each year in the United States, players of sports and recreational activities receive between 2.5 and 4 million concussions. How dangerous are all those concussions? The answer is complicated and lies in how the brain responds when something strikes it. The brain is made of soft, fatty tissue with a consistency something like jello. Inside its protective membranes and the skull's hard casing, this delicate organ is usually well-shielded. But a sudden jolt can make the brain shift and bump against the skull's hard interior. Unlike jello, the brain's tissue isn't uniform. It's made of a vast network of 90 billion neurons, which relay signals through their long axons to communicate throughout the brain and control our bodies. This spindly structure makes them very fragile, so that when impacted, neurons will stretch and even tear. That not only disrupts their ability to communicate, but as destroyed axons begin to degenerate, they also release toxins, causing the death of other neurons, too. This combination of events causes a concussion. The damage can manifest in many different ways, including blackout, headache, blurry vision, balance problems, altered mood and behavior, problems with memory, thinking, and sleeping, and the onset of anxiety and depression. Every brain is different, which explains why people's experiences of concussions vary so widely. Luckily, the majority of concussions fully heal, and symptoms disappear within a matter of days or weeks. Lots of rest and a gradual return to activity allow the brain to heal itself. On the subject of rest, many people have heard that you're not supposed to sleep shortly after receiving a concussion because you might slip into a coma. That's a myth. As long as doctors aren't concerned there may also be a more severe brain injury, like a brain bleed, there's no documented problem with going to sleep after a concussion. Sometimes, victims of concussion can experience something called post-concussion syndrome, or PCS. People with PCS may experience constant headaches, learning difficulties, and behavioral symptoms that even affect their personal relationships for months or years after the injury. Trying to play through a concussion, even for only a few minutes, or returning to sports too soon after a concussion, makes it more likely to develop PCS. In some cases, a concussion can be hard to diagnose because the symptoms unfold slowly over time. That's often true of subconcussive impacts, which result from lower impact jolts to the head than those that cause concussions.