It’s hard to think of a human environment that taxes a person’s circadian rhythm more than the International Space Station, where the workers — otherwise known as astronauts — experience almost 32 sunrises and sunsets (16 of each) in a 24-hour period.
That can wreak havoc on the biological clock, which expects one dawn and one nightfall per day — an habituation that began about 2.5 million years ago when early humans first started stretching awake in the morning and closing their eyes to sleep later.
The patterns of light and dark during those 24 hours are the principle determinant of the circadian rhythm. Mess with that physiological entrainment, and you’re asking for trouble. Sleep can be hard to come by, and health consequences can ensue.
Thus, over the years the Space Station has been a place for experimentation with tunable LED illumination. One approach has been to mimic the natural light patterns associated with the sun, in which the stimulating blue-enriched wavelengths during the course of day give way to more relaxing reds and ambers toward dusk.
The fascination up there with circadian lighting — also known as human-centric lighting — continues. When Danish astronaut Andreas Mogensen and the rest of the next crew lift off from Florida in August, the payload on their Crew Dragon space capsule will include a circadian lighting system from Denmark’s Saga Space Architects.
After they arrive at the Space Station some 260 miles above Earth, they will have Saga’s Circadian Light Panel to help normalize their sleep patterns.
“The lamp has three faces that emit light at different angles each,” Saga explains on its website.
“Each of these faces emits different wavelengths to promote alertness or induce sleepiness. Unlike current light systems onboard the ISS which have some manually operated kelvin and brightness controls, Saga’s light panel is programmed to automatically adjust the light accordingly to fit the astronaut’s planned sleep schedule,” according to Saga. “Through the meticulous use of different hues of color to simulate intense sunrises, varied daylight, and calming sunsets, the Circadian Light can carefully regulate the astronauts’ circadian rhythms to ensure that they focus during the day and sleep during the night. Compensating for the monotonous environment of space, the lighting system emits custom light for each individual day to simulate the natural change in lighting of shifting weather on Earth.”
The LED light sources for the Saga system come from Beijing-based Yujileds, which says that Mogensen will be the main user.
In addition to Mogensen, who is part of the European Space Agency (ESA), the crew will also include astronauts Jasmin Moghbeli from NASA, Satoshi Furukawa from the Japan Aerospace Exploration Agency (JAXA), and Konstantin Borisov from Russia’s Roscosmos.
They are currently scheduled to leave from NASA’s Kennedy Space Center on Aug. 15.
Plenty of earthlings will be keen to learn from the operations of the Saga lighting system, as human-centric lighting is still in the early days of deployment in both the consumer and business sectors, with plenty of research still to be done, and with implementations mainly making news in healthcare settings such as in dementia care facilities.
MARK HALPER is a contributing editor for LEDs Magazine, and an energy, technology, and business journalist ([email protected]).
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