Space Station Twilight Zone

NASA Identifier: iss002e5413 Night and day don’t exist on the International Space Station, where astronauts live in the equivalent of a twilight zone: Repeated exposure — or lack of exposure — to the wrong wavelengths of light at the wrong time disrupts their biological clocks and circadian rhythms. Still, the views are beautiful: This sunset view with the space station’s solar array in the frame was taken by the Expedition Two crew in 2010.

NASA Identifier: iss002e5413
Night and day don’t exist on the International Space Station, where astronauts live in the equivalent of a twilight zone: Repeated exposure — or lack of exposure — to the wrong wavelengths of light at the wrong time disrupts their biological clocks and circadian rhythms. Still, the views are beautiful: This sunset view with the space station’s solar array in the frame was taken by the Expedition Two crew in 2010.

The International Space Station orbits the Earth every 90 minutes, creating incredible photography opportunities for astronauts who see approximately 16 sunrises and sunsets in a 24-hour period. Night and day don’t exist on the space station, where astronauts live in the equivalent of a twilight zone: Repeated exposure — or lack of exposure — to the wrong wavelengths of light at the wrong time throws their biological clocks out of whack and disrupts their circadian rhythms. The astronauts are cut off from the natural light-dark cycle and therefore have to create their own.

Astronauts typically only get about six hours of sleep in a 24-hour period due to a number of factors, including circadian misalignment. They suffer from insomnia and fatigue: dangerous conditions in space where they are required to work slam shifts — the performance of critical, time-specific operations, such as docking. Sleep loss can severely impair the astronauts’ cognitive functions within a few days, increasing the risk of mission errors and putting their health and safety at risk.

So electric light is coming to the astronauts’ rescue to help with both circadian misalignment and providing an acute stimulant to reduce fatigue in the form of a programmable LED wavelength system being designed and tested by a specialized lighting team of neuroscientists and NASA engineers.

The LED lighting system being designed for the space station will far exceed the sophistication of the aging fluorescent lights now in place. The lighting system is scheduled to be installed in phases, starting in fall 2016 in the U.S. crew quarters and eventually expanding to the entire U.S. module of the space station.

Image courtesy of NASA This educational LED lighting model was prepared to illustrate the full-color spectrum of light that the new, programmable system will provide astronauts — a system that will allow for greater lighting control with the manipulation, or fine-tuning, of color wavelengths.

Image courtesy of NASA
This educational LED lighting model was prepared to illustrate the full-color spectrum of light that the new, programmable system will provide astronauts — a system that will allow for greater lighting control with the manipulation, or fine-tuning, of light’s wavelengths.

No, says neuroscientist Steven W. Lockley, the new LED lights (above) won’t really resemble disco lights. The new, programmable system will provide greater lighting control with the manipulation, or fine-tuning, of the wavelength and intensity of light to either stimulate, when alertness or circadian resetting is required, or not stimulate, for example prior to sleep, the circadian photoreception system. A system of multiple LEDs, he explains in talks, can produce thousands and thousands of combinations of light.

As a countermeasure for fatigue and circadian disruption, and to improve vision, health, safety, and performance, the astronauts will actually see variations of white light, designed to enhance or minimize stimulation as required.

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