Signs of a Concussion

What is concussion?

Concussion is a condition that occurs as a result of a traumatic brain injury (TBI). It involves the short suspension of the brain’s normal function as it responds to the impact of an injury to the head – such as a knock or fall.

Concussion can result from any injury in which the brain is jolted from its usual position to the extent that it hits the inner wall of the skull. This trauma can stretch or damage brain cells,[1] rendering it increasingly likely after trauma that the normal movements of the brain inside the skull, which would normally not cause any damage to the brain, could go on to result in bruising and bleeding.

Although this further damage to the brain will eventually be detectable using brain scans, concussion itself is initially a microscopic injury to the brain which will not be visually evident if the brain is scanned, e.g. by doing a CT scan of the head in the immediate aftermath of an injury.

For this reason, many cases of concussion go unnoticed or undiagnosed. Additionally, people do not always exhibit physical or behavioral symptoms of concussion, so it is important to monitor vigilantly for signs of concussion in all cases where a person has sustained an injury to the head. Although people experiencing concussion may display perceptible symptoms such as nausea, headaches and slurred speech, these may occur only several hours or days after the injury itself.

It is important to seek medical attention following any injury to the head in order to assess the likelihood of concussion and devise a recovery plan. This will be focussed on resting sufficiently and avoiding strenuous physical and mental activity, so as to allow the brain to recuperate and thereby limiting the likelihood of any possible concussion developing into a long-term condition.

Causes of concussion

Concussion is the most common kind of traumatic brain injury. It occurs as the result of a knock or jolt to the head, which causes the brain to move from its normal position inside the skull, damaging the cells in the affected area.

Activities which may result in head injuries, such as driving motor vehicles and playing sports, increase one’s chances of experiencing concussion. Knocking one’s head as a result of falling over can also result in concussion and is a principal cause of concussion in infants and the elderly.

The leading causes of concussion recorded by emergency departments are:[2]

  • Falling
  • Injuries related to motor vehicles
  • Accidentally being struck by or against an object
  • Assaults
  • Playing sports

According to the Journal of Athletic Training, approximately 300, 000 sport-related traumatic brain injuries occur in the United States annually, of which the majority are concussions. Motor vehicle crashes are the second most common cause of traumatic brain injury among people aged 15 to 24 years, and the most common cause of concussion across all age groups.[3]

Signs of concussion

Many people recover from concussion unaided, without necessarily noticing that they have experienced the condition. However, it is possible to develop post-concussion syndrome, where the symptoms of concussion persist for weeks, months or years after the injury took place. To ensure a full recovery from concussion and prevent this outcome with appropriate aftercare, it is important to be cognizant of the fact that anybody who has experienced a head injury may exhibit signs of concussion.

Concussion can cause a person to experience a temporary loss of consciousness, lasting for seconds, or minutes. Not everybody who experiences concussion loses consciousness, but, in cases where loss of consciousness does occur, the longer a person who has sustained a head injury remains unconscious, the more severe their concussion is likely to be. Medical attention should be sought in all cases where an injury to the head has resulted in loss of consciousness.

In addition to a possible loss of consciousness, a concussed person may display symptoms such as:[4]

  • Feeling confused
  • Feeling as though one is in a blur or fog
  • Forgetfulness, often extending to the circumstances which caused the concussion
  • Headache
  • Feeling pressure in the head
  • Ringing in the ears
  • Seeing stars
  • Slurred speech
  • Nausea
  • Dizziness

Some symptoms of concussion may not manifest until hours or days after the causal injury.

Symptoms of concussion which may appear later on include:[5]

  • Irritable mood and changes in personality
  • Sensitivity to light, noise and other external stimuli
  • Reduced ability to concentrate
  • Poor memory
  • Difficulty sleeping
  • Changes to the senses of taste and smell
  • Depression

Signs of concussion in children

While adults and teenagers tend to experience some or all of the symptoms of concussion listed above, it can be more difficult to spot the signs of concussion in children, toddlers and babies, especially as they may not be able to verbalize how they are feeling.

It is therefore vital that caregivers remain alert to the possibility that any child or infant who has experienced an injury to the head could be at risk of concussion. They must seek medical attention in all cases of suspected concussion and monitor children and infants for the signs of concussion associated with their age group.[6]

Signs of concussion in babies

Signs of concussion in babies can include:

  • A bump or bruise to the head
  • Changed sleeping habits; sleeping more or less can both be indicators of concussion
  • Crying when the head is moved
  • Vomiting
  • Changes in mood, especially increased irritability
  • Difficulty feeding

Signs of concussion in toddlers

Toddlers who are able to talk will generally be able to indicate whether they are feeling different from normal. This can be helpful in establishing whether a toddler may have concussion.

Signs of concussion in toddlers can include:

  • Nausea and/or vomiting
  • Behavioral changes
  • Loss of interest in their usual activities
  • Sleeping more or less
  • Excessive crying
  • Headache

Signs of concussion in children (aged two and above)

Children aged two and above tend to display more behavioral changes related to concussion, similar to those experienced by adults.

Signs of concussion in children can include:

  • Sensitivity to light and noise
  • Double vision
  • Dizziness, nausea and/or vomiting
  • Drowsiness
  • Irritability
  • Difficulty balancing
  • Sleeping more or less
  • Difficulty concentrating
  • Poor memory
  • Confusion about recent events
  • Changes in mood, especially sadness or nervousness

When to seek medical attention after a head injury

Many people make a rapid and fully recovery from concussion, but it is important to consult a doctor in all cases where the condition is suspected. Failing to rest and recuperate adequately when one has concussion can lead to the development of post-concussion syndrome, where the signs of concussion persist for weeks or months after the initial injury.

It is therefore important to seek medical attention immediately if one suspects that one, or one’s child, is feeling or behaving differently after sustaining an injury to the head, even if only one or two of the signs of concussion are apparent. Seeking medical attention is recommended in all cases where a child has experienced an injury more significant than a slight bump to the head,[7] i.e. any injury which causes bruising or bleeding or causes the child to indicate that they are experiencing pain.

There is usually no need to seek medical attention for suspected concussion after a minor head injury if a person of any age:

  • Remains alert
  • Has not been unconscious for any amount of time
  • Responds normally to speech
  • Is not dizzy, nauseous, or displaying any other age-appropriate indicators of concussion

When to seek emergency care

A person affected by severe concussion, i.e. involving a temporary loss of consciousness and/or a period of post-traumatic amnesia, will need immediate medical attention in order to establish the impact of their traumatic brain injury (TBI) on their brain, and to devise a recovery plan. Returning to day-to-day activities, especially playing sports, while suffering from an initial concussion can worsen its physiological and psychological impact, and can also increase the risk of incurring a second concussion.[8]

It is important to seek medical attention after a head injury if a person of any age presents symptoms which include:[9]

  • Losing consciousness for more than 30 seconds[10]
  • Having headaches repeatedly, or which worsen over time
  • Visible and persistent bumps, bruising or swelling anywhere on the head, particularly in children and infants
  • Nausea and vomiting getting worse instead of better
  • Becoming increasingly irritable over a number of days following the injury
  • Stumbling or being clumsy
  • Feeling disorientated, confused or experiencing difficulty recognizing familiar concepts
  • Slurred or altered speech
  • Seizures
  • Distorted vision and blurriness
  • Dilated pupils

Good to know: Doctors once used grading systems to establish the severity of a person’s concussion, particularly in sports medicine. The grading system would typically be used with the end goal of determining how much recovery time an injured player would need before returning to play.

The use of grading systems is now less common, but a popular means of assessing concussion is the Glasgow Coma Scale. This is a practical test for assessing how greatly a person’s consciousness is impaired. It can be used for all patients that have any kind of impairment of consciousness, including concussion. It is routinely used to screen a person’s neurological state if any kind of trauma to the head is suspected, for example, after an accident.

However, in most medical settings, doctors are now more likely to focus on determining appropriate treatment for a person to make a full recovery, for example, whether they will need emergency care or a breathing tube (intubation). As standard practice, doctors will evaluate concussion and advise on a recovery program on a case-by-case basis, taking all of a person’s symptoms and case-history into account.

Concussion FAQs

Q: Is it safe to fall asleep following concussion?
A: It is a myth that it is dangerous to fall asleep following a concussion. It was once believed that falling asleep after becoming concussed could result in slipping into a coma, but this idea has been discredited by medical research.[11] In fact, getting plenty of rest is of principal importance in recovering from concussion and allowing the trauma to the brain to heal. Consulting a doctor, followed by sleeping and/or resting is the best course of action for anyone affected by concussion, unless the doctor has advised that the concussed person needs to undergo further treatment related to the TBI.

Q: How long is the typical recovery period following concussion?
A: A recent study on the effect of cognitive activity level on the duration of post-concussion symptoms has revealed that the more one rests one’s brain ‒ including refraining from activities such as using computers and smartphones ‒ during the period after concussion, the more quickly normal brain function will be restored. In most people, perceptible symptoms of concussion resolve within around two weeks.

When post-concussion syndrome is not present, full recovery from concussion ‒ including the physical recovery of the brain from the injury, which will be imperceptible to the affected person ‒ can take as long as up to 100 days. This can be significantly reduced to around 20 or 30 days, by ensuring that one refrains from returning to one’s normal day-to-day activities and rests appropriately.[12]

Q: What is post-concussion syndrome (PCS)?
A: Post-concussion syndrome (PCS) is a rare condition in which people continue to experience symptoms related to their concussion for weeks, months or even years, if left untreated after the injury that led to their concussion. These may include sleeping problems, difficulty remembering things, fatigue, dizziness, headaches, depression and sensitivity to noise and light. Treatment will involve addressing the specific symptoms that each person with PCS experiences. With appropriate medical supervision, PCS relieves over time in most cases.

For more information about PCS, see this resource on post-concussion syndrome.

Q: What can a person do to facilitate effective recovery from concussion?
A: The most important element of recovering from concussion is allowing one’s brain to rest, both through getting sufficient sleep and through ensuring that one takes a break from one’s normal working or school hours and from sporting activities. Returning to work or school before the brain has recovered to the point where symptoms are no longer present can increase the chances of prolonging the concussion. If the symptoms of concussion return, this may be an indicator that one has rushed the recovery process and returned to one’s usual routine too soon. Medical attention should then be sought and a revised recovery plan devised.[13]


  1. What is a concussion?”. US Department of Health and Human Services, Centres for Disease Control and Prevention (CDC). 24 October 2013. Accessed: 20 October 2017.

  2. “[Facts about concussion and brain injury: where to get help](https://www.cdc.gov/headsup/pdfs/providers/facts_about_concussion_tbi-a.pdf].” US Department of Health and Human Services, Centres for Disease Control and Prevention (CDC). 2010. Accessed: 20 October 2017.

  3. Concussions Among United States High School and Collegiate Athletes.” Journal of Athletic Training. October - December 2007. Accessed: 20 October 2017.

  4. Signs and Symptoms of Concussion.” US Department of Health and Human Services, Centres for Disease Control and Prevention (CDC). 22 March 2017. Accessed: 20 October 2017.

  5. Mild traumatic brain injury: a neuropsychiatric approach to diagnosis, evaluation, and treatment.” Neuropsychiatric Disease and Treatment. December 2005. Accessed: 20 October 2017.

  6. Academic Effects of Concussion in Children and Adolescents.” American Academy of Pediatrics. 11 May 2015. Accessed: 20 October 2017.

  7. Office management of mild head injury in children and adolescents.” CFP MFC: Official Publication of the College of Family Physicians of Canada. June 2014. Accessed: 20 October 2017.

  8. Cerebral Concussion: Causes, Effects, and Risks in Sports.” Journal of Athletic Training. July - September 2001. Accessed: 20 October 2017.

  9. Concussion.” American Association of Neurological Surgeons. 2017. Accessed: 20 October 2017.

  10. Traumatic Alterations in Consciousness: Traumatic Brain Injury.” Emerging Medical Clinicians of North America. 28 August 2010. Accessed: 20 October 2017.

  11. Is it safe to sleep if you have a concussion?.” University of Arkansas for Medical Sciences. 2017. Accessed: 20 October 2017.

  12. “[Effect of Cognitive Activity Level on Duration of Post-Concussion Symptoms])http://pediatrics.aappublications.org/content/pediatrics/133/2/e299.full.pdf).” American Academy of Pediatrics. 06 January 2014. Accessed: 20 October 2017.

  13. Recovery.” US Department of Health and Human Services, Centres for Disease Control and Prevention (CDC). 22 January 2016. Accessed: 20 October 2017.