LED Lighting for Better Health

Well designed artificial lighting can reduce negative effects on the body’s circadian clock, and might even bring health benefits.

Compared with conventional incandescent or fluorescent bulbs, LEDs use less energy, last longer and contain no glass or mercury, negating the risk of glass shards or toxic metal floating through the space station should the bulbs break in zero gravity. But researchers also hope that the new lighting system will help astronauts to sleep better at night and to stay alert during the day.

The problem that engineers are trying to address is that there’s no ‘day’ or ‘night’ in space. The ISS circles Earth every 90 minutes or so, which provides astronauts with frequent opportunities to see the Sun rise and set, but also wreaks havoc on the body’s roughly 24-hour, or circadian, clock. Among space flight’s many deleterious effects on health, disturbance of the circadian rhythm and the sleep deprivation that accompanies it have emerged as considerable worries.

The LED-based lighting system being introduced to the ISS is designed to target not just rods and cones — photoreceptor cells in the eye that enable vision in dim light and in colour, respectively — but also a third type of photoreceptor cell that was discovered almost 20 years ago. Known as intrinsically photosensitive retinal ganglion cells (ipRGCs), these photoreceptors contain a light-sensitive protein called melanopsin. They don’t have much of a role in vision; instead, ipRGCs serve as the body’s main entry point for light that regulates biological functions such as the sleep–wake cycle, alertness and mood. Researchers are beginning to understand the extent to which too much or too little light at the wrong time of day can throw important physiological processes out of sync, whether you’re an astronaut on a spacecraft, a nurse on the night shift, or just playing computer games after bedtime.

Artificial lighting has extended the length of time for which people are exposed to light each day, for better or for worse. LED-based dynamic lighting systems that are capable of adjusting the colour and intensity of the light that they deliver should make it possible to design lit environments that are less detrimental to health.

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