Exposure to light at critical phases of the circadian cycle is the main stimulus that entrains circadian rhythms. Previous work has concluded that exposure of humans to bright light for an hour or more at the right phase of the circadian cycle produces significant phase shifts of circadian rhythms speeding recovery from jet-lag, and optimizing cognitive functionality and restorative sleep. Our work on mice produced the unexpected result that exposure to intermittent millisecond flashes of light distributed over an hour for a total of only 120 msec. of light can produce maximum phase shifts. We have also shown that the effects of light on the circadian system of mice is mediated through a unique photopigment melanopsin, and the properties of this system explain the effectiveness of brief flashes of light as entraining signals. We propose to develop and test a wearable light flash system that will have the ability to phase shift human circadian rhythms and thereby mitigate the consequences of travel across time zones. This system will be automated to deliver the right stimulus depending on time and location, it will require little power, and it interfere minimally with night vision.
Benefit: The system that will be developed and tested in this project will make it possible to mitigate circadian rhythm disruptions due to shift work, travel across time zones, and irregular work schedules. It will be wearable by awake or sleeping individuals, run on AA batteries, and cause minimal impairment of night vision. We also believe that the device will be effective in treating seasonal affective disorder (SAD).
Keywords: Circadian Phase Shifting, Melanopsin, Light Flashes, Jet-Lag.
