Pre-frontal blood flow, "NIR on" versus "placebo". A comparison of the mean left-, right-sided, and left + right pre-frontal total hemoglobin (cHb) measurements (arbitrary, relative units) recorded during the two 4-minuted NIR treatments (F3 and F4), light on conditions, and during the two 4-minute placebo (LED off) conditions (F3 and F4). cHb is an index of regional cerebral blood flow (rCBF). Mean rCBf across hemispheres (left + right/2) increased from 0.011 units in the sham condition to 0.043 units in the treatment condition, for a difference of 0.032 (95% CI: -0.016, 0.080) units, though this result did not reach statistical significance (t9 = 1.52, p = 0.16). The increase with treatment was 0.046 (95% CI: -0.004, 0.097; t9 = 2.07, p = 0.07) units in the left hemisphere and 0.018 (95% CI: -0.033, 0.069; t9 = 0.80, p = 0.44) units in the right hemisphere, but the difference between hemispheres was also not statistically significant (95% CI for difference: -0.01, 0.063; t9 = 1.83; p = 0.10). Error bars represent 1 standard error from the mean.