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Understanding the Mechanisms of Blue Light Exposure on Cognitive Performance

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[Technical Report, Final Report]

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Blue light exposure shows promise as a safe and easily implemented intervention to improve attention, increase cognitive functioning and enhance mood. However, the exact mechanism that explains these beneficial effects is currently unknown, hindering the ability to make effective recommendations to military personnel regarding itsoptimal use. We studied acute exposure to blue light or an amber placebo light during functional magnetic resonance imaging fMRI, with simultaneous assessment of pupil size as a proxy for norepinephrine release. Results suggest that acute exposure to blue light was potentially effective for sustaining neural efficiency. We found that a brief exposure to blue light in the scanner, during a time when melatonin levels were low, was associated with significantly suppressed deactivation of the default mode network, a brain system that is usually disengaged by difficult cognitive effort. This suggests that the brain exerted less effort during the task during blue light than amber, without alteration in performance. Melatonin levels and pupil size were unaffected by the light. However, we also found evidence that a brain region proximal to the location of the locus coeruleus LC, a primary drive or norepinephrine release was also more activated by blue light than amber. We conclude that even brief exposures to blue light may provide an important and potentially effective method for sustaining cognitive performance

Subject Categories:

  • Anatomy and Physiology
  • Anatomy and Physiology

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[A, Approved For Public Release]