The ISS uses its indoor lighting system to simulate a 24-hour day-night cycle. How does light on board the ISS impact astronaut health? Lighting inside the Destiny Laboratory Module on board the ISS during astronauts’ work time (Source: NASA). Our circadian rhythm is connected to the light-dark cycle on Earth, so if people don’t get those light and dark cues from their environment they can have negative health effects. The circadian rhythm is our body’s natural clock, which controls our sleeping and eating patterns. This can be a problem for astronauts’ circadian rhythms. One of the many things that is different about living on board the International Space Station (ISS) is that astronauts get to see 16 sunrises and sunsets each day! Because the ISS orbits the Earth every 90 minutes, astronauts on board don’t have the same sense of day and night that we do on Earth, which rotates once every 24 hours. Light on the International Space Station How do astronauts experience light? 500 lx is best in areas that teachers use most. 300 lx in areas where students work most. So, what is the optimal or ‘best’ range for light in a classroom? The best range is between 250 - 500 lx. People who design lighting also need to consider other things such as safety, maintenance and cost. For example, theatres and stairwells are usually fairly dim (200 lx) kitchens, libraries and grocery stores are brighter still (500 lx), and operating rooms are very bright (1 000 lx). People who design indoor lighting try to find a light level (lux) that works best for the things people do in those spaces. If a room is very dark, it is possible for people to bump into objects.
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They may even get sleepy because light stops the production of melatonin, a hormone that makes people sleepy. If lux levels are too low, people can also strain their eyes and get headaches. It is even possible to damage one’s eyes if light sources and lux is too high. An overly bright room can also make it difficult to concentrate. If lux levels are too high, people can strain their eyes and get headaches. The brightness of light on surfaces around us can affect how we feel physically as well as mentally.
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How does light affect our mental and physical health? A candle showing the difference between luminous flux, luminous intensity and illuminance (© 2019 Let’s Talk Science using an image by OpenCipArt-Vectors via Pixabay).