What Happens to Your Brain When You Get a Concussion?

Elizabeth Sandel, MD, author of Shaken Brain, has reviewed this article for accuracy.

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What is a concussion?

A concussion, also known as a mild traumatic brain injury (mTBI), is an injury to the brain caused by a blow or jolt to the head – or a blow to the body that causes the head to move and the brain to shift rapidly inside the skull – that disrupts normal brain functioning. When we say “concussion” moving forward, we’ll be talking about an mTBI. When we talk about cells, know that cells are small building blocks that make up all living organisms. Different types of cells have different roles. A concussion causes damage to cells in the brain on a tiny level. Moderate to severe traumatic brain injuries (TBI) are different from concussions because they are marked by structural injury to the brain as well as cell injury.

What’s my brain made out of?

Let’s walk through an overview of the brain. Your brain is made up of cells, and the most important brain cells are called neurons. Neurons have axons, which connect these cells to each other and help them communicate. An axon is a part of the neuron that reaches out like an arm. A neuron communicates by using its axon to connect with another neuron, just like a person reaches out with their arm to pat a friend on the back.

Connections between billions of neurons in your brain create a complicated web of pathways for your cells to communicate with each other. Your neurons and these connections allow you to do a wide range of tasks, such as throwing a ball, thinking, learning a new language, and processing emotions.

How can I get a concussion?

The main ways you can get a concussion are from direct force to the head, or “a hit to your body that is strong enough to cause your head to forcefully jerk backwards, forwards or to the side.” Falls, car accidents, and sports-related injuries are the leading causes of documented concussions in the US. People can get concussions from the shockwaves of explosive blasts. Strangulation, often from partner-inflicted violence, can also cause a brain injury.

What does a concussion do to my brain?

You get a concussion as a result of your brain moving suddenly inside your skull and shaking like jello as it returns to rest.

This brain movement hurts your neurons by causing them to stretch and sometimes break. The sudden brain movement causes damage which is labeled as a concussion.

Why does a concussion give me symptoms?

Injured neurons have a harder time communicating, and some connections between neurons in the brain may also be broken because of the concussion. These injuries at the cellular level make it harder for the brain to do its job. Since the brain has so many responsibilities, a concussion can make it harder to function.

What are common symptoms of a concussion?

If you are recovering from a concussion, you might feel more sensitive to light, sound, movement, and others around you. Common symptoms include difficulty with headaches, memory, irritability, balance, visual processing, sleep, and hormonal changes. Even though others may not notice a difference, if you “feel different,” it’s important to realize that your experiences can likely be explained by your injury.

A lack of understanding by medical professionals and others around you is an unfortunately common situation that can make your injury feel invisible. To learn more about how this may affect you and find advice for you and your supporters, check out our page on invisible injury.

Why are my neurons having trouble functioning?

Injuries to the neurons cause chemicals to leak in and out of the cells.

The leaking destabilizes your neurons away from their typical state. Returning your neurons to their typical state requires large amounts of energy.

How can brain imaging help me?

When you go to the ER or see a medical professional, they will make a concussion diagnosis based on their evaluation of your symptoms. The most accessible brain imaging devices, like MRI or CT, usually show no evidence of brain injury in concussion patients. As we explained above, concussions occur at the cellular level, so the damage is too small to be seen with these scans. Though MRI and CT are not useful alone for diagnosing a concussion, they are valuable for ruling out more serious TBI-related structural damage to the brain and skull, such as bleeding. See our immediate care page for red-flag symptoms that may require follow-up with a medical professional.

a graphic of a person holding their hands to their head and "stars" spinning around their head

Why is my brain making less energy than normal?

Normally, blood carries lots of energy-rich nutrients to your brain, but a concussion may decrease blood flow to your brain. This means that the energy supply into your brain has been weakened. The leaking of chemicals in injured neurons in your brain also damages mitochondria. Mitochondria are the energy-producing centers of each cell, so injured neurons can't produce as much energy. Low blood input and low mitochondrial energy production help explain why there is less energy available to your brain.

Why do I feel more tired than usual?

A concussion weakens your brain’s ability to make and supply energy for healing. To make matters worse, a concussed brain needs more energy than normal to restore balance and heal. This gap between your lower energy supply and higher energy demand explains why you may feel extremely tired after a concussion.

On top of this energy shortage, your brain is prioritizing its limited energy for healing, which means that you have less energy available for daily functioning. It’s common for people recovering from a concussion to feel they are always “running out of energy.”

Why am I more vulnerable to re-injury after a concussion?

It is critically important to protect your brain from another concussion during this energy shortage. Sustaining a follow-up concussion before your brain has fully healed can be disastrous. Research shows that, after a second concussion, your recovery takes longer and you may have a greater number and intensity of symptoms, as well as increased vulnerability. In rare cases, a second concussion too soon after the first can cause second impact syndrome which can lead to coma or death.

It’s extremely important that athletes are immediately removed from the game after a possible concussion. Even a few minutes of continued play can increase the number of symptoms and recovery time.

How long does it take for my brain to metabolically recover?

According to The Berlin 5th International Consensus on Concussion, metabolic recovery take 10-14 days for adults and one month for youth 18 and under. However, recovery time can vary from person to person and is not always predictable. It’s important to know that symptomatic recovery is on a different timeline from metabolic recovery.

Feeling better and having no more symptoms does not necessarily mean that your brain has healed and is ready for full action: it is still healing and especially vulnerable to a secondary concussion. The energy shortage and vulnerability to additional injuries has a lot of potential to become worse, and it is important to be especially careful during this initial, fragile stage of recovery.

Is my brain able to heal & will my symptoms go away?

Fortunately, your brain can repair and heal itself! It is valuable to remember that your brain can be retrained. Networks between neurons can be reshaped, rebuilt, and strengthened. This process can help you function better. With care, you can improve your quality of life and your symptoms can get better. This result is more than just possible; it is within reach.

Who can I lean on for support?

It’s okay to ask for help. People around you want you to be well. With the help and support from friends, family, and medical professionals, you can find your own path towards recovery. For individuals with persistent symptoms, it is valuable to build a team of medical specialists, where each specialist can offer deeper support for a subset of your symptoms in order to improve your recovery.

Many healthcare providers (including general practitioners, physical therapists, vestibular therapists, occupational therapists, and more) can support you in your medical recovery and rehabilitation. Friends, family members, teachers, teammates, colleagues, and more can all support you in your personal recovery. Which member of your support team has the power to make the most difference? It’s you.

Your mentality towards your recovery is invaluable: protect it as much as you can, and allow other people to help you.

Where can I learn more?

One resource that’s helped us better understand concussions and how to care for this injury is the book Shaken Brain: The Science, Care, and Treatment of Concussion 1st Edition, by Elizabeth Sandel, MD. We recommend her book as a place to find some of the most up to date knowledge on concussions.