Short-Wavelength Countermeasure for Circadian Desynchrony

Air Force operations often expose flight crew and support staff to unusual light-dark cycles that causes misalignment of the circadian pacemaker and sleep-wake cycles, resulting in disturbed sleep and impaired waking function. Air Force personnel are also frequently required to remain vigilant, often under conditions of acute or chronic sleep deprivation. An effective countermeasure is required to facilitate rapid adaptation of the circadian system and/or to enhance alertness and performance directly. Light induces both of these effects and is a safe, non-pharmacological countermeasure for circadian- and fatigue-related cognitive deficits. Recently, we have shown that short-wavelength (blue) light at night is the most effective wavelength for phase-shifting the circadian pacemaker, suppressing melatonin, enhancing subjective alertness, improving performance and inducing brain activation. Further work is required to confirm that blue light is also the most effective wavelength in the day and at all light intensities. In this proposal, we aim to compare the effectiveness of day-time blue or green narrow-band LED exposure to enhance alertness, performance and EEG activation using a small, portable light source (goLITE, Apollo Light Systems Inc.). Based on these results, we intend to develop a `smart' portable LED light source to enhance alertness and performance in operational settings.