A concussion feels like your brain has been knocked out of sync with the rest of your body. The most common sensation is a headache, often described as pressure or heaviness inside the skull, paired with a foggy, slowed-down feeling that makes it hard to think clearly. But the experience goes well beyond a bad headache. Concussions affect how you process light and sound, how steady you feel on your feet, how well you sleep, and even your mood.
The Headache and Physical Sensations
Nearly everyone with a concussion experiences a headache, though it varies in character. Some people feel a dull, constant pressure across the forehead or temples. Others describe a throbbing pain that worsens with physical activity, bending over, or even just moving their eyes. The headache can start immediately after the impact or build gradually over hours.
Beyond the headache, you may feel physically drained in a way that seems out of proportion to what happened. Fatigue after a concussion isn’t ordinary tiredness. It’s a deep, whole-body exhaustion that doesn’t improve much with rest, at least in the first few days. Nausea is common too, sometimes with vomiting right after the injury, sometimes as a lingering queasiness that flares when you move your head quickly.
Why Your Brain Feels “Off”
The foggy, disconnected feeling that defines a concussion has a biological explanation. When the brain is jolted inside the skull, it triggers a chemical disruption at the cellular level. Ions flood in and out of brain cells in the wrong direction, and the brain burns through its energy stores trying to restore normal function. At the same time, blood flow to the brain can drop significantly, meaning the brain is working harder while receiving less fuel. This mismatch between energy demand and energy supply is what produces that sluggish, clouded mental state. It also explains why symptoms tend to worsen when you try to push through mentally demanding tasks.
In practical terms, this feels like thinking through mud. You might read the same sentence three times without absorbing it, forget what you were about to say mid-sentence, or struggle to follow a conversation with more than one person. Reaction times slow noticeably. Simple decisions, like what to order at a restaurant, can feel overwhelming. Many people describe it as being “not quite here,” present but operating at half speed.
Sensitivity to Light and Sound
One of the more distinctive concussion experiences is a sudden, uncomfortable sensitivity to light and noise. Fluorescent lights, phone screens, and sunlight can feel almost painful, triggering or intensifying headaches. Grocery stores, restaurants, and busy hallways become difficult to tolerate because the visual complexity and ambient noise are simply too much for the injured brain to process efficiently.
Noise sensitivity tends to be especially stubborn. Research has found it’s more common and slower to resolve than light sensitivity. It’s not that sounds are louder exactly. It’s that ordinary sounds, a TV at normal volume, background chatter, a dog barking, produce an outsized discomfort response. Some people also notice that their ears feel “full” or that sounds seem distorted, though true hearing loss isn’t part of a typical concussion.
Dizziness and Balance Problems
A concussion can disrupt the connection between your inner ear, your eyes, and your brain, which is the system that keeps you balanced and oriented in space. This can produce several unsettling sensations. The room may seem to spin, a feeling called vertigo, or you may feel persistently off-balance, as though you’re about to tip over even while standing still. These sensations can come on suddenly or be triggered by specific movements like turning your head quickly, looking up, or rolling over in bed.
Many people also notice that their vision feels “off” even though their eyesight hasn’t changed. Focusing on a moving object can be difficult, and scrolling on a phone or watching fast-paced video may trigger nausea or worsen dizziness. This happens because the brain’s ability to coordinate eye movement with head movement is temporarily impaired.
Mood Changes and Irritability
Concussions affect emotions in ways that can catch people off guard. Irritability is one of the most reported mood changes. Things that wouldn’t normally bother you, a minor inconvenience, a child’s noise, a coworker’s question, can trigger a sharp, disproportionate frustration. Anxiety is also common, sometimes as a general feeling of unease and sometimes as a more specific worry that something is seriously wrong.
Some people feel unusually sad or emotionally flat without a clear reason. Others swing between emotions more quickly than normal. These changes aren’t a sign of weakness or a separate psychological problem. They’re a direct result of the same metabolic disruption causing the headaches and brain fog. The brain regions involved in emotional regulation are affected just like the ones involved in memory and concentration.
Sleep Disruption
Sleep problems after a concussion take different forms. Some people have trouble falling asleep despite feeling exhausted. Others sleep far more than usual, sometimes 12 or more hours, and still wake up feeling unrested. The quality of sleep itself is often poor, with frequent waking, vivid dreams, or difficulty staying in deep sleep. This creates a frustrating cycle: the brain needs quality rest to heal, but the injury itself makes restful sleep harder to achieve.
Symptoms Can Be Delayed
Not everything shows up right away. Some concussion symptoms appear within minutes, particularly headache, confusion, and dizziness. But others can take hours or even days to develop. You might feel mostly fine the evening of an injury, then wake up the next morning with a pounding headache, brain fog, and sensitivity to light that wasn’t there before. This delayed onset is one reason concussions are sometimes missed initially. If you took a hit to the head and feel “a little off” but not terrible, the full picture may not emerge until the following day.
Memory gaps are another common experience, particularly around the injury itself. You may not remember the moment of impact or the minutes immediately before and after it. In some cases, you might ask the same question repeatedly without realizing you’ve already asked it. This type of amnesia usually resolves within hours to days.
How Long It Lasts
More than 80 percent of concussions resolve within the first three weeks when managed properly. Most people notice steady improvement starting around days three to five, with the worst symptoms, particularly the headache and intense fatigue, easing first. Cognitive symptoms like difficulty concentrating and memory lapses tend to linger a bit longer but still clear within a few weeks for the majority of people.
A smaller percentage of people experience symptoms that persist beyond a month, a condition sometimes called post-concussion syndrome. When this happens, the lingering issues tend to be headaches, difficulty sleeping, dizziness, trouble concentrating, and noise sensitivity. These aren’t signs of a new or worse injury. They reflect a brain that’s taking longer to complete its metabolic recovery, sometimes complicated by poor sleep, stress, or returning to activity too quickly.
Symptoms That Signal Something More Serious
Most concussions are classified as mild traumatic brain injuries and resolve on their own. But certain symptoms suggest a more severe injury that needs immediate medical attention. A headache that keeps getting worse and won’t go away is one of the clearest warning signs. Repeated vomiting, seizures, slurred speech, increasing confusion, weakness or numbness in the limbs, or one pupil appearing larger than the other all warrant an emergency room visit. Loss of consciousness at the time of injury doesn’t happen in every concussion, but when it does, particularly if it lasts more than a few seconds, it’s worth getting evaluated promptly.