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The Power of Light - presented by Science@NASA
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Crew members on the International Space Station (ISS) can experience sunrises and sunsets in rapid succession -
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about 16 "sunsets" per day because the space station circles Earth once every 90 minutes.
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Most people function regularly on a 24-hour cycle known as a circadian rhythm.
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However the space station environment creates a departure from the cycle of light and dark astronauts are used to at home.
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A high workload, the need to work 'nightshifts', the excitement of spaceflight, plus the unusual environment can disrupt astronauts' circadian clocks.
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These factors can combine to disrupt sleep, which can in turn affect performance.
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Being wide awake when they should be sleeping is in fact a long-standing challenge among ISS crew members.
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Studies of astronauts who flew between 2001-2011 on the space shuttle, and 2006-2011 on the station,
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showed that astronauts slept considerably less in space than they did on Earth.
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About 3/4 of them reported using sleep promoting pills during their 6-month missions.
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Use of caffeine is also commonplace among ISS astronauts, to fight off the daytime drowsies.
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But NASA is seeking a better way to solve the problem, the secret lies in light itself.
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It's known that the blue-enriched light emitted by our laptops can keep us awake at night.
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A new NASA study will investigate how to use that for the benefit of humankind, and not just on the ISS.
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This light study -- known as the Lighting Effects study -- coincides with a lighting 'makeover' on the space station.
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The fluorescent lights on the station are being replaced with a new system of solid-state light-emitting diodes (LEDs).
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Not only are the LEDs more energy-efficient and safer, they can literally shed all sorts of light on the study topic.
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Brigham and Women's Hospital's Dr. Steven Lockley, and Thomas Jefferson University's Dr. George Brainard are the co-principal investigators of the Lighting Effects study.
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Lockley explains: "Light has a number of effects on our sleep and circadian rhythms;
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is a natural stimulant and can improve alertness and performance, and also help reset the 24-hour clock when it gets out of sync.
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The human eye contains a light-sensitive protein called melanopsin, different from the rods and cones that we use to see,
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which detects light in the eye and mediates these effect.
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Melanopsin is most sensitive to short-wavelength blue light and so by increasing or decreasing the proportion of these blue wavelengths in white light,
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we can enhance alertness, or promote sleep, respectively."
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Lockley says, "NASA has developed a multi-LED lighting system to take advantage of these light effects.
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The system can provide millions of different light spectra.
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We're not making the ISS into a disco, but we are going to use three different light settings.
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We'll use a general light setting that provides a good light to see by during normal work,
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a higher-intensity blue light enriched setting that elevates alertness and can better shift the circadian clock when needed,
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and a lower-intensity blue wavelength-depleted 'pre-sleep' setting to calm the brain and promote sleep.
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We will be studying the impact of these lights in future missions."
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"Oh you guys it is so fancy, it is really awesome!
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I think the technical term is, light functional checkout was successful so congratulations to the light team."
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Results of this study are expected to help define guidelines for lighting protocols during future ISS and human space missions.
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Study results should make it clear exactly when and how to use these various settings of light intensity and spectrum.
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These results could also lead to Earth-based benefits such as helping manage sleep patterns for shift workers,
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or even developing treatments for sleep disorders or jet lag.
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For more from the International Space Station, visit www.nasa.gov/station.
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For more news about the power of light, stay tuned to science.nasa.gov.