The Short Answer Educational content only. Any suspected concussion warrants medical evaluation. Persistent sleep disturbance after concussion warrants assessment by a physician or sleep medicine specialist. Consult a concussion-experienced clinician for individualized care. Light therapy helps the post-concussion circadian rhythm by delivering strong, timed light to the master clock in the hypothalamus, resetting a rhythm that concussion disrupts (Silverberg et al., 2020). Light is the clock's main timing signal, and concussion weakens both the clock and its response to daily light. Bright light delivered at the right time strengthens the day-night signal and shifts the clock toward the desired schedule. Morning light advances a delayed rhythm, the most common post-concussion pattern, improving sleep timing, daytime alertness, and mood. The timing of light determines its effect, so treatment pairs timed light with a consistent schedule and, in circadian disorders, melatonin timing guided by testing. Light is the master clock's main timing signal. Morning light advances a delayed post-concussion rhythm. The timing of light determines its effect on the clock. How Light Sets the Circadian Clock The master clock in the hypothalamus receives light information directly from the eyes through specialized retinal cells that respond to brightness. This input tells the clock whether it is day or night and keeps the internal rhythm aligned with the outside world. Morning light advances the clock, promoting earlier sleep and waking. Evening light delays it, pushing sleep later. Bright, blue-enriched daytime light strengthens the overall day-night signal, sharpening the contrast between active day and restful night. Concussion weakens this system. The injury can disrupt the clock and the light pathways feeding it, and reduced daytime activity during recovery lowers light exposure. The result is a flattened, poorly aligned rhythm. Light therapy restores the strong, timed signal the clock needs. How Concussion Disrupts the Light Signal Two things go wrong after concussion. First, the injury can affect the clock and its light input, reducing the clock's ability to stay aligned. Second, recovery behavior reduces light exposure. People spend more time indoors, get less morning light, and often use bright screens in the evening. The daytime signal weakens while the evening signal strengthens, flattening the rhythm and frequently pushing it late. Light therapy corrects both problems by adding a strong, correctly timed light signal. How Morning Light Therapy Works For the common delayed pattern, bright light in the morning is the core treatment. Exposure soon after the target wake time advances the clock, pulling the sleep window earlier over successive days. A light therapy device delivering around 10,000 lux for 20 to 30 minutes provides a reliable dose, and morning time outdoors provides strong natural light. Consistency matters more than any single session, since the clock shifts gradually. Timing is critical. Light given at the wrong point in the rhythm shifts the clock the wrong way, so morning light is used to advance a delayed clock and evening light to delay an advanced one. In circadian disorders, matching the light to the clock's actual position, established through melatonin onset testing, produces the most reliable result. Benefits Beyond Sleep Timing Earlier, more consolidated sleep in a delayed rhythm Improved daytime alertness and reduced sleepiness Better mood, since bright light has an antidepressant effect A sharper day-night rhythm that supports deep and REM sleep Reduced reliance on sleep medication Support for overall recovery through better sleep Assessment and Timing A clinician tailors light therapy to the person's circadian pattern. A sleep log and actigraphy establish the current sleep timing. Dim light melatonin onset testing pinpoints the clock's position and guides when to apply light, which matters most in clear circadian disorders. Light sensitivity is common after concussion, so treatment starts gently, with shorter exposures and gradual increases, and stops if it provokes headache or symptom flare. A concussion-experienced clinician balances the circadian benefit against light sensitivity. Treatment Approach Morning bright light anchors the day for a delayed rhythm, delivered soon after the target wake time and paired with a consistent wake time seven days a week. Getting outdoors in the morning adds strong natural light. Reducing evening light and screens removes the delaying signal that competes with the treatment. For an advanced rhythm, the timing reverses, with bright light applied in the evening to delay the clock. Because light sensitivity is common early in recovery, exposures start short and build gradually. In circadian rhythm disorders, light therapy is combined with timed melatonin and schedule advancement for the most reliable realignment, ideally guided by a sleep specialist. Post-concussion sleep improves faster when daytime nervous system regulation improves. Start your 3-day free trial to build a daily mobility and breathing routine that supports recovery. Supporting Mobility Routine JME 155 Diaphragmatic breathing shifts the nervous system toward parasympathetic tone before bed through vagal stimulation. Ten slow breaths with long exhales, twice in the evening. JME 14 Chin tucks release upper cervical extensor tension that sustains sympathetic drive and disrupts settling. Ten repetitions with 5-second holds. JME 1 Cervical rotation restores segmental mobility and reduces the neck tension that fragments early sleep. Ten repetitions per direction. JME 15 Cervical lateral flexion addresses side-bending restriction that keeps the neck from relaxing on the pillow. Ten repetitions per side. JME 16 Cervical flexion and extension restore sagittal mobility restricted by suboccipital guarding. Eight slow repetitions. JME 2 Cervical retraction reinforces a neutral head position that reduces overnight muscular strain. Ten repetitions per set. JME 150 Thoracic rotation restores mid-back motion required for full diaphragmatic breathing and comfortable side sleeping. Eight repetitions per direction. JME 227 Overhead reach opens the thoracic spine and rib cage, supporting the deep breathing that lowers arousal at night. Ten repetitions with controlled tempo. Start your 3-day free trial for joint-specific mobility programming that supports nervous system regulation and sleep after concussion. Common Mistakes Using light at the wrong time and shifting the clock the wrong way Starting with long, intense exposures that provoke light sensitivity and headache Applying light inconsistently, so the clock never fully shifts Keeping bright evening screens that undo morning light gains Ignoring the clock's actual position rather than testing it in circadian disorders Progression Assessment establishes the circadian pattern and the clock's timing. Light therapy starts gently to respect light sensitivity, with short morning exposures that build over days. A consistent wake time and reduced evening light support the shift. In circadian disorders, timed melatonin and gradual schedule advancement are added. Sleep timing, alertness, and mood improve over one to several weeks as the clock realigns. When should I use light therapy for post-concussion sleep? For the common delayed pattern, bright light soon after the target wake time advances the clock and pulls sleep earlier. For an advanced pattern, evening light delays the clock. Timing is critical, since light at the wrong point shifts the clock the wrong way. A clinician matches the timing to your circadian pattern. How bright does light therapy need to be? A light therapy device delivering around 10,000 lux for 20 to 30 minutes provides a reliable dose, and morning time outdoors gives strong natural light. Because light sensitivity is common after concussion, exposures start shorter and build gradually, stopping if they provoke headache or symptom flare. Can light therapy make concussion symptoms worse? Light sensitivity is common after concussion, so poorly dosed light can provoke headache or symptom flare. Starting with short exposures and increasing gradually, under a concussion-experienced clinician, balances the circadian benefit against sensitivity. Most people tolerate a gentle, graded approach. Does light therapy help mood as well as sleep after concussion? Yes. Bright light has an antidepressant effect in addition to its circadian benefit, and improving sleep timing itself supports mood. Morning bright light often improves daytime alertness, mood, and sleep together, which is helpful given how these symptoms overlap after concussion. Do I need melatonin testing to use light therapy? Not for general sleep hygiene use, where consistent morning light and a stable schedule help. For a clear circadian rhythm disorder, dim light melatonin onset testing pinpoints the clock's position and guides when to apply light for the most reliable realignment. A sleep specialist decides when testing is warranted. Why Sleep Matters After Concussion Sleep drives the brain's recovery after injury. During deep sleep, the glymphatic system clears metabolic waste from brain tissue, a process that slows during wakefulness (Xie et al., 2013). Sleep also consolidates memory, regulates mood, and restores autonomic balance. Disrupted sleep after concussion slows recovery across every symptom domain, and improving sleep often improves headache, cognition, mood, and fatigue at the same time. Sleep Foundations That Support Recovery Consistent sleep and wake times anchor the circadian rhythm, which concussion disrupts. Keep the same schedule seven days a week during recovery. Get bright light exposure within an hour of waking to set the clock, and dim lights in the two to three hours before bed. Avoid screens close to bedtime, since evening light suppresses melatonin and delays sleep onset. Keep the bedroom cool, dark, and quiet. Reserve the bed for sleep. Avoid caffeine after midday and limit alcohol, which fragments sleep and suppresses deep and REM stages. A brief wind-down routine with diaphragmatic breathing lowers arousal and eases the transition to sleep. During early recovery, short daytime naps are appropriate when fatigue is high, kept before mid-afternoon so they do not delay night sleep. Red Flags Requiring Evaluation The following warrant prompt medical or sleep medicine evaluation. Loud snoring with witnessed breathing pauses or gasping Excessive daytime sleepiness that impairs driving or work safety Falling asleep suddenly during activity Acting out dreams with movement that risks injury to self or a bed partner Sudden loss of muscle tone with strong emotion Progressive worsening of sleep despite good sleep habits Mood decline, hopelessness, or thoughts of self-harm Any concern about breathing during sleep, dangerous daytime sleepiness, or safety warrants same-week evaluation rather than watchful waiting. Multidisciplinary Care Considerations Post-concussion sleep disturbance rarely occurs in isolation. Coexisting headache, mood symptoms, autonomic dysregulation, and cervical dysfunction all interact with sleep. Coordinated care produces better outcomes than treating sleep alone. A team includes a concussion physician, a sleep medicine specialist for testing and sleep-disorder management, a psychologist for cognitive behavioral therapy for insomnia, and a physical therapist for cervical and autonomic contributors. Cognitive behavioral therapy for insomnia is the first-line treatment for chronic post-concussion insomnia and outperforms sleep medication for durable benefit. References Xie, L., et al. (2013). Sleep drives metabolite clearance from the adult brain. Science, 342(6156), 373-377. PubMed Patricios, J. S., et al. (2023). Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport, Amsterdam, October 2022. British Journal of Sports Medicine, 57(11), 695-711. PubMed Silverberg, N. D., et al. (2020). Management of concussion and mild traumatic brain injury: a synthesis of practice guidelines. Archives of Physical Medicine and Rehabilitation, 101(2), 382-393. PubMed