Blue-light therapy following mild traumatic brain injury: Effects on white matter water diffusion in the brain

Sahil Bajaj, John R. Vanuk, Ryan Smith, Natalie S. Dailey, William D.S. Killgore

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Mild traumatic brain injury (mTBI) is a common and often inconspicuous wound that is frequently associated with chronic low-grade symptoms and cognitive dysfunction. Previous evidence suggests that daily blue wavelength light therapy may be effective at reducing fatigue and improving sleep in patients recovering from mTBI. However, the effects of light therapy on recovering brain structure remain unexplored. In this study, we analyzed white matter diffusion properties, including generalized fractional anisotropy, and the quantity of water diffusion in isotropic (i.e., isotropic diffusion) and anisotropic fashion (i.e., quantitative anisotropy, QA) for fibers crossing 11 brain areas known to be significantly affected following mTBI. Specifically, we investigated how 6 weeks of daily morning blue light exposure therapy (compared to an amber-light placebo condition) impacted changes in white matter diffusion in individuals with mTBI. We observed a significant impact of the blue light treatment (relative to the placebo) on the amount of water diffusion (QA) for multiple brain areas, including the corpus callosum, anterior corona radiata, and thalamus. Moreover, many of these changes were associated with improvements in sleep latency and delayed memory. These findings suggest that blue wavelength light exposure may serve as one of the potential non-pharmacological treatments for facilitating structural and functional recovery following mTBI; they also support the use of QA as a reliable neuro-biomarker for mTBI therapies.

Original languageEnglish (US)
Article number616
JournalFrontiers in Neurology
Issue numberNOV
StatePublished - Nov 22 2017
Externally publishedYes


  • Concussion
  • Diffusion tensor imaging
  • Fractional isotropy
  • Isotropic diffusion
  • Neuropsychological function
  • Quantitative anisotropy
  • Sleep
  • Structural recovery

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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