Green Light Therapy to Treat Migraine - Quick Reference Sheet

Green Light Therapy to Treat Migraine

Created on 08/24/2026 – Quick Reference based on Evidence Review created using AI4L / Opus 5 Audit

Narrow-band green light at low brightness, for hours daily or during an attack. Green is reliably the least painful colour during a migraine. Reductions in headache days rest on studies where everyone knew the treatment, rated very low certainty. With frequent attacks, one-time cost and no reported harm tilt the balance toward a bounded trial; brighter light makes headaches worse. (Full Review)

Protocol

Arizona preventive protocol
1–2 hours daily, 10 weeks
Green light-emitting diode strips at low intensity, viewed indirectly in an otherwise dark room, with existing treatments continued unchanged.
Boston acute protocol
~2 hours during an attack
Narrow-band green exposure during an attack rather than daily prevention.
Wavelength and intensity
520–530 nm, low intensity
Narrow bandwidth. Intensity matters more than exact wavelength: the therapeutic window is low, and the benefit inverts as brightness rises.
Time to effect
Acute relief
Single 1–2 hour session
Acute relief, where it occurs, is reported within a single session.
Preventive reduction in attack days
4–10 weeks
Reduction in attack days accrued over 4–10 weeks in trials.
Fair assessment
At least 10 weeks
Benefit accrued across weeks and faded after exposure stopped.

Benefits

Contraindications
  • Photosensitive epilepsy, or any seizure disorder with a documented seizure response to flickering light
  • Active retinal disease (retinitis pigmentosa, advanced proliferative diabetic retinopathy, wet age-related macular degeneration under active treatment)
  • Recent intraocular or refractive surgery (within 4 weeks), or prescribed post-operative light restriction
  • Retina-damaging drugs without eye-specialist clearance (hydroxychloroquine >5 mg/kg/day or beyond 5 years, chloroquine, long-term thioridazine)
  • Bipolar I disorder with documented light-therapy-associated or seasonal mood elevation
  • Children under 18
Key Interactions
  • Melatonin supplements (caution; blunted effect)
  • Sedating over-the-counter sleep aids (caution; blunted effect; diphenhydramine, doxylamine, melatonin-containing formulas)
  • Light-sensitising drugs (caution; skin reaction is not the issue; amiodarone, voriconazole, doxycycline, hydrochlorothiazide)
  • Antiseizure medications (caution; flicker not colour; valproate, lamotrigine, topiramate)
  • Migraine drugs (no interaction; additive symptom relief; sumatriptan, ubrogepant, erenumab)
  • Migraine preventive supplements (additive benefit; monitor; magnesium, riboflavin, coenzyme Q10)
  • Other nerve-stimulation devices (caution; confounded assessment; arm-worn, scalp-current, neck-worn units)

Risk & Side Effects

  • High: Headache exacerbation and visual discomfort at higher intensities
  • Medium:
  • Low: Melatonin suppression and delayed sleep onset from evening sessions; non-response and delayed escalation to proven preventives; blunted preventive effect in colour vision deficiency
  • Speculative: Retinal photochemical stress from prolonged narrow-band exposure

Monitoring

Marker Target Why
Red blood cell magnesium 5.5–6.5 mg/dL Low magnesium is an established, correctable migraine driver
25-hydroxyvitamin D 40–60 ng/mL Low status associates with higher attack frequency and poorer sleep
Ferritin 50–100 ng/mL Iron depletion worsens fatigue and headache burden, especially in menstruating women
Homocysteine Below 8 µmol/L Elevation flags folate or B-vitamin methylation issues linked to migraine with aura
hs-CRP Below 1.0 mg/L Screens for the low-grade inflammation that tracks with progression to chronic migraine
Thyroid-stimulating hormone 0.5–2.0 mIU/L Both under- and over-active thyroid states present with headache and disturbed sleep
Overnight urinary 6-sulfatoxymelatonin No established target; track change from own baseline before and after 6 weeks of evening sessions Detects whether late sessions are suppressing night-time melatonin

Cadence: Baseline panel drawn before the first session, repeated at 3 months, then every 6–12 months, with any corrected marker rechecked sooner. Headache diary scored continuously and formally reviewed at 4 weeks, 10 weeks, and every 3 months thereafter.

Qualitative Assessment

  • Monthly headache days, counted from the diary, as the primary success measure
  • Peak attack intensity on a 0–10 scale, recorded separately from frequency
  • Acute medication days per month, the marker most relevant to medication-overuse risk
  • Photophobia severity between attacks, the symptom the mechanism directly targets
  • Time to fall asleep and total sleep time, watched for drift after evening sessions
  • Work and household function on attack days, and general energy on non-attack days
  • Cognitive clarity during and after sessions