Post-Concussion Syndrome PBM Support: What to Check When Headaches Persist

Why Headaches Won't Resolve Six Weeks After a Concussion

You hit your head in a minor fender-bender, went to the ER, got a CT scan, and were told nothing was wrong. Six weeks later your temples still throb most mornings, and ten minutes in front of a monitor is enough to tighten something behind your eyes. Climbing stairs a little too fast or checking your phone on the subway brings a wave of dizziness, and by evening your concentration is so far gone that a routine email takes twice as long as it should. A clear scan right after the injury does not mean the symptoms disappear along with the imaging report.

When this state carries on past the usual recovery window, it is called post-concussion syndrome (PCS). During this stretch, neither total bed rest nor forcing your way back into a full schedule speeds things up — both tend to slow recovery down. Lying in a dark room for too many days deepens the dizziness and the fatigue, while ignoring the symptoms and jumping straight back into your old routine tends to bring the headaches and the mental fog roaring back, and the cycle repeats. This article walks through why headache and cognitive symptoms drag on after a concussion, what criteria you can use to check your own status, when the situation calls for a doctor rather than home management, and how a week-by-week approach to near-infrared photobiomodulation (PBM) fits in as a supplementary measure alongside everything else.

Why Headaches and Dizziness Can Drag On for Weeks

A concussion is an injury that happens when brain tissue, suspended in cerebrospinal fluid, shakes rapidly enough to cause subtle functional disruption to neurons and their axons. The reason a CT or MRI usually shows nothing — no bleeding, no fracture — is that the damage happens at the level of cell membranes and ion channels, not at a scale imaging can capture.

In the moments after impact, potassium and calcium concentrations inside and outside neurons swing sharply out of balance, and the cells burn through far more ATP than usual trying to pump them back to normal. At almost the same time, local blood flow to the affected tissue tends to drop temporarily, which is the opposite of what the cells need. Neurosurgeons Christopher Giza and David Hovda described this in a widely cited 2001 framework known as the neurometabolic cascade, built from a combination of animal studies and human imaging work. It is a useful conceptual model, but it was never designed to predict how long any individual patient's recovery will take, and it should not be read that way. When the gap between rising energy demand and falling supply lasts days to weeks, neurons stay in a more sensitive-than-normal state, which shows up as headache, sensitivity to light and sound, an inability to tolerate screens for long, and a sharp drop in energy after even brief concentration.

Neck and shoulder involvement is very often part of the picture too. The whiplash-style forward-and-back motion of the neck at the moment of impact frequently causes its own small-scale damage to the muscles and joints around the upper cervical spine. Pain signals from that region converge with trigeminal nerve input inside a structure in the brainstem called the trigeminocervical nucleus, where the two signal pathways essentially overlap and amplify each other — which is part of why neck-driven pain can be perceived and felt as head pain. That convergence point is exactly why a stiff, guarded upper neck three or four weeks after a whiplash-type impact keeps triggering headache spikes even when nothing new is happening to the head itself. This is a large part of why post-concussion headache so often needs to be evaluated alongside neck muscle tension rather than treated purely as a brain problem, and it overlaps with cervical-spine management principles covered in our Disc Herniation Conservative NIR Care Guide.

Criteria for Checking Whether You Have Post-Concussion Syndrome

Some headache or dizziness for a day or two after an injury is a normal part of recovery. The concern is when symptoms outlast the usual recovery window. The table below lists five symptom domains along with the duration that should raise your level of concern.

In clinical practice, when three or more of these five domains are still present at the four-week mark, it is often approached as post-concussion syndrome rather than a simple delay in recovery. That said, this is not a rigid cutoff that applies identically to everyone — a prior history of migraine or an earlier concussion changes the expected recovery speed considerably. People with a migraine history in particular tend to report longer and more intense post-concussion headache than people without one.

When you're checking your own status, it helps to note the time of day and the activity that preceded each flare-up. Keeping a simple running log of screen time, caffeine intake, and hours slept alongside your symptom notes gives you a much more accurate baseline to work from when you start adjusting your activity level in the weeks that follow — rather than guessing at which trigger caused which bad afternoon.

Warning Signs That Mean You Should See a Doctor Now

Most cases of post-concussion syndrome are not medical emergencies, but the following signs mean you should stop self-managing and get to an emergency department or a neurologist right away. This applies with particular urgency if any of these appear newly or worsen sharply in the first few days after the injury.

• Headache that keeps getting worse over time: especially if it no longer responds to over-the-counter pain medication
• Repeated vomiting: not a single episode, but several in a row
• Decreased level of consciousness: unusually drowsy, or difficult to wake up
• Seizure activity: convulsions affecting part or all of the body
• Weakness, numbness on one side of the body, or slurred speech: neurological signs that a simple concussion does not explain
• Pupils that appear different sizes from one eye to the other
• Worsening confusion: not recognizing people or places you normally know well

Even if none of these apply to you, if you have stuck with self-management for four weeks or more and your symptoms have not improved at all — or worse, they're spreading into new areas — it is safer to get evaluated by a neurologist or a rehabilitation medicine specialist. Post-concussion syndrome often needs input from several specialties working together — a headache clinic, vestibular rehab, cognitive rehab — so getting professional direction early usually shortens the overall recovery timeline more than sticking with a single home approach for months on end.

Step-by-Step Management Protocol: What to Check Week by Week

The most common mistake in managing post-concussion syndrome is trying to judge recovery speed on a day-to-day basis. In practice, it is far safer to increase activity gradually on a week-by-week basis while watching closely for any return of symptoms. The table below lays out activity targets by phase, alongside a reference framework for how near-infrared (PBM) exposure can be layered in as a supplementary measure.

The International Concussion in Sport Group's consensus statement, drawn from its 2016 Berlin meeting and published by McCrory and colleagues in 2017, breaks a graduated return-to-activity process into six stages, recommending at least 24 symptom-free hours at each stage before moving to the next. It's worth noting this consensus was built primarily around acute, sports-related concussion recovery, so it shouldn't be applied wholesale to every case of chronic post-concussion syndrome — the duration of each stage needs to flex around the individual's actual symptom pattern rather than following a fixed calendar.

A few concrete markers make the week-to-week judgment call less subjective. If a symptom that had settled down flares back up within a few hours of increasing activity, that's a signal to repeat the current week rather than advance — pushing forward anyway is the single most common reason recovery stalls out around week three or four. A more reliable indicator than how you feel on any single day is whether you can repeat the same activity level on three consecutive days without a flare-up; a good day sandwiched between two bad ones does not count as readiness to progress. Stop signs that should pause any increase in activity or PBM use include a headache that spikes rather than gradually eases within an hour of the session, new visual disturbance, or a level of fatigue that forces you to cancel plans for the rest of the day.

When layering in PBM, skip the first few days if acute swelling or noticeable warmth is still present, and start with short sessions once the subacute phase sets in and the main complaint has shifted to a dull, stiff ache in the neck and shoulders rather than sharp pain. If neck muscle relaxation is a bigger part of the picture, the irradiation techniques covered in our Frozen Shoulder Rehabilitation with LED Therapy Program are worth reviewing as well.

Common Mistakes and How to Correct Them

A handful of mistakes show up again and again in how people manage post-concussion syndrome. Here they are, along with the correction for each.

Staying in a dark room until every symptom is gone

Relative rest for the first 24-48 hours after the injury is genuinely useful, but keeping yourself in near-total isolation for weeks afterward tends to make dizziness, low energy, and disrupted sleep worse rather than better. It's more productive to bring back short walks or light housework as soon as they don't sharply worsen your symptoms — full darkness past the first two days is a sign to start easing back in, not to hold the line longer.

Taking headache medication nearly every day

Occasional pain relief is fine, but taking it three or more times a week on a habitual basis can tip over into medication-overuse headache, which becomes very hard to tell apart from the original post-concussion headache. If you notice your own dosing frequency creeping upward week over week, that's the moment to go back to a headache specialist and rebuild the plan rather than continuing to increase the dose on your own.

Jumping straight back to full intensity because you feel fine

A few good days in a row can be misleading. Returning immediately to your old work pace or exercise intensity skips over the staged protocol described above, and the rebound that follows — symptoms flaring back up harder than before — is extremely common. Sticking to the planned stage even on days you feel great, rather than treating a good day as permission to skip ahead, is what actually shortens the total recovery timeline.

Cutting off screens completely

Reducing screen exposure early on genuinely helps, but going weeks with essentially no phone or monitor use tends to increase social isolation and low mood, which works against recovery rather than for it. A more realistic approach is to dim the brightness and break usage into short 5-10 minute blocks that you gradually lengthen. If shoulder and neck pain is being aggravated by screen posture at the same time, it's worth reviewing the posture-correction section of our Shoulder Impingement NIR Rehabilitation Guide alongside this.

Starting near-infrared irradiation while acute swelling or warmth is still present

Applying near-infrared light to the neck or shoulder while there are still clear signs of acute inflammation — noticeable warmth, visible swelling — tends to increase discomfort rather than help. It's safer to wait until the acute phase passes and the pain has shifted to a dull, stiff ache before starting with short sessions.

Applying This to Everyday Situations

Even with the same diagnosis of post-concussion syndrome, what needs adjusting looks different depending on your actual circumstances.

Your first week back at a desk job

Rather than jumping straight into a full eight-hour day, it's safer to start with a half-day in the morning and stretch the hours out gradually every two to three days. Dropping your monitor brightness below its usual level and setting a firm rule — 50 minutes of work, then five minutes fully away from the screen — cuts down on headache recurrence considerably more than most people expect.

When driving is unavoidable

While dizziness or slowed reaction time is still present, long-distance driving — night driving especially — is best avoided. Start with short, familiar routes, and test yourself with a passenger in the car first rather than driving alone the first few times back behind the wheel.

Athletes and physically demanding jobs

Not skipping the six-stage return protocol described earlier matters more here than almost anywhere else. In any sport with a real risk of re-collision, returning before you've genuinely recovered raises the risk of a second concussion, and a brain that's still recovering is known to be more vulnerable to a second impact — which is exactly why the decision to clear someone for full return during this window should always be made together with a medical professional, not on how a given practice session felt.

Students and workers facing exams or deadlines

Rather than cramming concentration into one long block, breaking study or work into 20-25 minute segments with five minutes of eyes-closed rest or stretching in between tends to trigger fewer headaches while still holding up reasonably well against a tight deadline.

Parents who can't simply take time off from childcare or housework

When complete rest isn't realistic, a workable compromise is to hand off the noisiest, most visually demanding stretches of the day — getting kids ready for school, grocery runs — to another family member where possible, and to schedule short recovery routines like near-infrared sessions or neck stretches during the quieter parts of the day instead.

Why Near-Infrared Photobiomodulation (PBM) Comes Up for Post-Concussion Syndrome

Near-infrared light comes up in post-concussion syndrome management along two separate lines of reasoning. One is the hypothesis that direct irradiation of the scalp and underlying brain tissue supports neural recovery. The other is the more indirect approach of relaxing neck and shoulder muscle tension to reduce headache. Both are worth stating up front as areas still under active research rather than settled fact.

Margaret Naeser, leading a cognitive neurology research team at Boston University, published an open-label study in the Journal of Neurotrauma in 2014 examining red-light and near-infrared LED irradiation applied to the scalp of patients with chronic mild traumatic brain injury. The study enrolled 11 chronic patients — months to years past their original injury — who received a total of 18 sessions over four to five months, twice weekly, and reported that some cognitive test scores improved from baseline. The limitations are worth stating plainly: there was no control group, the design was open-label, and a sample of 11 is very small, which makes it difficult to separate any real treatment effect from natural recovery over time or from a practice effect on repeated cognitive testing. It's more accurate to treat this as an early-stage observation that calls for controlled follow-up research, not as evidence that near-infrared irradiation resolves post-concussion symptoms.

On the mechanism side, Michael Hamblin of Harvard Medical School published a review in the Journal of Neuroscience Research in 2016 outlining how near-infrared light is thought to stimulate cytochrome c oxidase inside mitochondria, increasing ATP production and improving local blood flow. In simplified terms, the light is absorbed by this enzyme in a way that briefly displaces bound nitric oxide, which in turn allows oxygen to bind more efficiently and the cell's energy-production chain to run more effectively — the proposed mechanism for the ATP increase described above. This review draws together animal research and small human studies, and it is not a source that quantifies how much a real headache or cognitive symptom would actually improve in clinical use. Related applications of near-infrared light in neurological rehabilitation are covered from a similar angle in our Photobiomodulation (PBM) in Post-Stroke Rehabilitation article.

Put together, there is still no large randomized controlled trial that would justify claiming near-infrared irradiation treats or cures post-concussion syndrome. The realistic way to approach it today is as a supplementary wellness measure for easing neck and shoulder muscle tension, used alongside a graded activity-return plan and stretching — not as a substitute for a medical professional's diagnosis and care.

Precautions and Expert Advice

A few rules are worth following closely whenever near-infrared light is used as a supplementary measure. Never irradiate directly into the eyes, and wear protective goggles when using it near the scalp or face. If you're taking medication that can cause photosensitivity — certain antibiotics, antiarrhythmics, and chemotherapy agents among them — check with your prescribing physician before starting. Avoid direct irradiation of a pregnant abdomen, any area with a suspected active malignancy, or a head area where acute bleeding is suspected.

Stop immediately if you notice persistent redness, blistering, or increased pain in the treated area. Above all, near-infrared irradiation should be understood clearly as a complementary wellness measure, not a substitute for professional medical care. If you've stuck with self-management for four weeks or more without improvement, or if a new neurological symptom appears, don't wait — get evaluated by a neurologist or a rehabilitation medicine specialist.