A concussion is a brain injury that affects cognitive function. It can be caused by a blow to the head, a head-on collision (for example, two football players bumping helmets), or violent shaking. A mild form of traumatic brain injury (TBI), concussions cause cognitive, emotional, and physical symptoms. Physical and mental rest are the primary treatment for concussion.

Key Terms

Frequently Asked Questions

  • How long does a concussion last?

    In general, most concussion symptoms take two to three weeks to resolve with proper rest, although each concussion is different. An undiagnosed or poorly treated concussion can take months or even longer before you feel like yourself again. If you are still experiencing symptoms 14 days after your injury, check in with your doctor.

  • How do you treat a concussion?

    Concussion is treated primarily with physical and cognitive rest. This includes avoiding physical activity, reading, screen time, and even music. How long you need to rest will depend on the severity of the concussion and its symptoms. After a day or two of complete rest, it is recommended to ease back into activities and let symptoms be your guide. If a particular activity triggers symptoms, avoid it for a while.

  • How do you know if you have a concussion?

    A concussion is caused by trauma to the head. Symptoms are usually present within minutes to several hours after the impact and include headache, nausea, vomiting, confusion, dizziness, blurry vision, tinnitus, sensitivity to light and noise, difficulty focusing, and drowsiness.

    Some people may temporarily lose consciousness, but do not have to be knocked out to have a concussion.

  • How do you check for a concussion?

    If you have suffered a blow to the head or been in a car accident, a physical and neurological examination can determine if you have a concussion. Your doctor will check your vision, balance, coordination, and reflexes, and evaluate your memory and cognitive function. A brain scan, such as a computerized tomography (CT) or magnetic resonance imaging (MRI), may be ordered to rule out a skull fracture and check for a brain bleed or inflammation.

  • What are the symptoms of a concussion?

    Concussion symptoms are a mix of cognitive, physical, emotional, and sleep-related issues. The primary physical symptom is a headache. Other symptoms include confusion, memory problems, difficulty focusing and thinking, dizziness, nausea, vomiting, blurry vision, tinnitus, sensitivity to light and noise, and drowsiness.

  • Can you sleep with a concussion?

    Yes, you can sleep with a concussion. Years ago, the advice was to wake head-injury patients hourly to assess their status, but this changed with imaging technology like CT and MRI. However, each concussion is different, and you should follow your doctor’s guidance.

A Closer Look at Concussions

Explore interactive models below that illustrate what happens to a brain inside the skull during a head injury, and how damaged brain cells (neurons) can cause the symptoms of a concussion.

Page Sources
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  1. American Society of Neuroradiology. Traumatic Brain Injury (TBI) and Concussion.

  2. American Association of Neurological Surgeons. Concussion.

  3. U.S. Department of Defense: Blast Injury Research Coordinating Office. What is blast injury? Updated June 18, 2019.

  4. U.S. National Library of Medicine: MedlinePlus. Cognitive testing. Updated February 24, 2020. 

  5. American Academy of Ophthalmology. Dilate Pupils. Updated September 30, 2020. 

  6. Merck Manual (Consumer Version). Overview of imaging tests. Updated July 2019.

  7. Johns Hopkins Medicine. Neurological exam.

Additional Reading