A concussion is a mild traumatic brain injury caused by a bump, blow, or jolt to the head that disrupts normal brain function. It doesn’t always involve losing consciousness, which is why many go unrecognized. The injury occurs at the cellular level, where brain cells are stretched and stressed. This can lead to chemical changes that temporarily interfere with communication between neurons. While symptoms usually resolve, every concussion should be taken seriously.

During a concussion, the brain moves rapidly inside the skull, which can cause stretching of nerve cells. This mechanical force disrupts normal electrical signals and alters the brain’s chemistry. Blood flow may be reduced, leaving the brain temporarily less efficient at using energy. These changes can explain why people feel foggy, tired, or confused after injury. Recovery depends on the brain restoring balance to its cells and networks.

Concussion symptoms can be physical, emotional, and cognitive. Physical signs include headaches, dizziness, blurred vision, nausea, or sensitivity to light and sound. Emotional changes may involve irritability, sadness, or increased anxiety. Cognitive symptoms often include trouble concentrating, slowed thinking, or memory difficulties. Symptoms may appear right away or develop hours to days after the injury.

A concussion is diagnosed through a clinical evaluation rather than a single test. Doctors ask about the injury, review symptoms, and may perform neurological exams to check memory, balance, and coordination. Brain scans such as CT or MRI are only ordered if there is concern for bleeding or other serious injury, but they cannot diagnose a concussion itself. Because symptoms can be subtle, honest reporting is crucial. Diagnosis is the first step in ensuring safe rest, monitoring, and gradual return to activity.