Fatigue is a very common symptom after a head injury, such as a concussion, because the brain has to work much harder to function normally while it heals. When the brain experiences trauma, it uses extra energy to repair itself and manage the disruption caused by the injury. This increased effort drains the body’s energy reserves, leading to a feeling of overwhelming tiredness that is different from ordinary fatigue[1].
After a head injury, many people report feeling mentally slow or foggy, making even simple tasks like reading or watching TV exhausting. This mental fatigue often lasts longer than physical tiredness because cognitive activities require more brain power during recovery. The brain’s slowed processing and difficulty concentrating contribute to this sensation of fatigue[2][3].
Sleep disturbances are also common after a head injury and can worsen fatigue. People may have trouble falling asleep, staying asleep, or experience irregular sleep patterns. Sometimes they sleep more than usual but still wake up feeling unrested. Poor sleep quality means the brain does not get the rest it needs, which prolongs feelings of tiredness during the day[4][9].
In some cases, fatigue after a head injury can be persistent and part of a condition called post-concussion syndrome. This syndrome includes symptoms like headaches, dizziness, brain fog, and ongoing tiredness that last for weeks or months. Prolonged rest without gradual activity can lead to physical deconditioning and metabolic changes that increase fatigue further[6].
Severe fatigue or extreme drowsiness after a head injury can be a warning sign of a more serious problem. If someone has difficulty staying awake or is hard to wake up, it is important to seek immediate medical attention[5].
In summary, fatigue after a head injury happens because the brain is using extra energy to heal, cognitive tasks become more demanding, sleep is often disrupted, and sometimes symptoms persist due to post-concussion syndrome. Recognizing this fatigue as a sign that the brain needs time and proper care to recover is important.
Sources
https://lakecountryphysio.com/7-common-symptoms-concussion/
https://www.amenclinics.com/do-you-know-these-10-signs-of-post-concussion-syndrome/
https://www.tfhd.com/conditions/concussion/
https://www.concussionalliance.org/persisting-symptoms-after-concussion
https://www.thechampionfirm.com/blog/head-injury-severity-after-car-accident/
https://www.cognitivefxusa.com/blog/post-concussion-syndrome-why-your-symptoms-linger-how-to-recover
https://www.gncdubai.com/tired-time-maybe-bumped-head-research-says/
https://www.massgeneralbrigham.org/en/about/newsroom/articles/signs-concussion-child
