Concussion: what a mild brain injury actually needs to heal
Last updated September 3, 2026.
A concussion is a mild traumatic brain injury: the brain gets shaken inside the skull, and for days to weeks it works below par while it heals. You do not need to be knocked out: most concussions happen without loss of consciousness, and scans are usually normal because the injury is functional, not structural. Most people recover fully within 2-4 weeks, but the recovery rules have changed: strict dark-room rest is out, and guided light activity is in.
What does it look like?
Symptoms can appear immediately or develop over hours: headache, feeling dazed or foggy, dizziness, nausea, sensitivity to light and noise, blurred vision, slowed thinking, and memory gaps around the event. Sleep gets disturbed (too much or too little), emotions run raw (irritability, anxiety, low mood), and concentration frays. In children: clinginess, crying more than expected, appetite and sleep changes, and losing interest in favorite activities. Symptoms that worsen over days instead of improving, or new neurological signs, are the red-flag pattern. Most concussions improve steadily and resolve in 2-4 weeks in adults, up to 4 weeks or slightly longer in children and teens.
The recovery rules that changed
The old advice was complete rest in a dark room until symptom-free; research now shows that prolonged strict rest actually slows recovery. The current approach: 24-48 hours of relative rest, then a gradual return to light activity (short walks, light screen time) that stays below the level that significantly worsens symptoms, building up daily. Full return to sport follows a staged protocol, each step at least 24 hours, back a step if symptoms flare. Driving, alcohol, and contact sport are off until cleared. A second concussion before the first has healed is the dangerous scenario (second impact syndrome in the young, and longer, harder recovery in everyone), which is why return-to-play is rule-bound, not vibes-based.
What actually helps?
- First 24-48 hours: relative rest: quiet, low stimulation, short naps fine, someone stays with you, and paracetamol for headache (avoid ibuprofen in the first day if there is any question of bleeding).
- Then graded activity: light walking and normal daily tasks, keeping symptoms from flaring significantly; extend a little each day.
- Screens in moderation: brief sessions with breaks are fine after the first days; hours of scrolling is the thing that flares symptoms.
- No alcohol, no driving, no contact sport until cleared: all three raise risk while the brain heals.
- Protect the recovery from a second hit: this is the whole logic of return-to-play protocols; follow the steps, do not negotiate them.
When is it an emergency?
Go to emergency care now for: a headache that worsens and will not settle, repeated vomiting, increasing drowsiness or difficulty waking, a seizure, slurred speech, weakness or numbness on one side, unequal pupils, clear fluid or blood from the nose or ears, confusion or agitation, or any loss of consciousness beyond a moment. In children, add: will not stop crying and cannot be consoled, or refusing food. These suggest bleeding or swelling, not concussion, and every hour matters. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Do you have to be knocked out to have a concussion?
No, and this is the most important myth to retire: the large majority of concussions involve no loss of consciousness at all. A knock, fall, or whiplash that leaves you dazed, foggy, or with a headache qualifies. Being knocked out raises the level of concern and the need for assessment, but its absence says nothing reassuring by itself. The diagnosis rests on the symptoms after a head impact, not on whether you blacked out.
Should I stay awake, or keep a concussed person awake?
Let them sleep. The old keep-them-awake rule came from fear of missing a brain bleed, and it was wrong advice that added sleep deprivation to a brain trying to heal. The correct approach: someone stays nearby and checks on them periodically in the first 24 hours, and sleep is fine, including overnight. What is not fine is a person who cannot be woken, or who is increasingly drowsy and hard to rouse: that is an emergency. Normal, rousable sleep is healing.
How long does concussion recovery take?
Most adults recover fully in 2-4 weeks; children and teens typically need up to 4 weeks, sometimes a little more. About a fifth of patients have symptoms beyond a month (persistent post-concussion symptoms), needing a structured rehab plan rather than just more waiting. Predictors of slower recovery: a history of prior concussions, high early symptom load, migraines, anxiety, and, avoidably, both over-exertion too early and prolonged total rest. Steady improvement, even slow, is the reassuring trajectory.
When can I (or my child) return to sport?
After full symptom resolution at rest and during exercise, via a staged return-to-play protocol: typically light aerobic activity, then sport-specific exercise, then non-contact training drills, then full-contact practice, then play, with at least 24 hours per step and a step back for any symptom flare. For children and teens, return to school (learning) comes before return to sport (collision risk). Medical clearance before contact is the formal gate in most organized sport, and it exists because a second concussion before healing is genuinely dangerous.
Is strict rest in a dark room still the advice?
No; the evidence moved. The 2016-2023 consensus shifted from cocooning to guided activity: 24-48 hours of relative rest, then light activity (walking, gentle daily tasks, short screen sessions) kept just below the threshold that significantly worsens symptoms, building daily. Studies showed that prolonged strict rest produces more symptoms and slower recovery, likely through deconditioning and anxiety. Symptoms that spike badly with activity still mean back off a step; the point is graduated exposure, not heroics.
Do helmets prevent concussion?
Helmets prevent skull fractures and scalp injuries excellently, but they do not prevent concussion, which is the brain moving inside the skull, and no helmet stops that deceleration. Wear the helmet anyway, for the injuries it does prevent. The concussion-prevention levers are different: enforcing no-head-contact rules, neck strengthening, mouthguard use in some sports (modest evidence), and honest symptom reporting so a first concussion is not followed by a second on the same day.