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Two office chairs
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You've probably heard of circadian rhythms, the natural body cycles that help us to do things like fall asleep at nighttime and be active during the day.

Now, a group of researchers are working to manipulate those rhythms to make us more productive at work.

"Clients are increasingly requesting and expecting lighting systems and applications that can support human health and well-being," Mariana Figueiro and Mark Rea, professors at the Lighting Research Center at Rensselaer Polytechnic Institute, wrote in Architectural Lighting recently.

The issue is critical, because according to the Environmental Protection Agency, humans in modern cities spend upwards of 90 percent of their lives indoors.

Multiple tests now show that humans are particularly sensitive to blue light — basically, the main color we see when we're outdoors. Blue's main effect is to suppress melatonin, the brain chemical that can make us feel sleepy.

As Scientific American noted in November, a 2011 investigation by Christian Cajochen, the head of the Center for Chronobiology at the University of Basel, found that volunteers exposed to a blue-based, LED-backlit computers for five hours in the evening "produced less melatonin, felt less tired, and performed better on tests of attention than those in front of a fluorescent-lit screen of the same size and brightness."

Researchers are thus increasingly advising office designers to include as much daylight-like blue in their offices as possible.

[CORRECTION: An earlier version of this story stated that red lighting is conducive to functioning at night, without explaining that there is no universal consensus on the research. The story has been updated.]

In order to promote our natural cycles, “one should keep exposure to light at night as short as possible, as dim as possible, and as warm or red as possible,” Steven Lockley, an associate professor of medicine in the division of sleep medicine at Harvard Medical School and at Brigham and Women’s Hospital in Boston, said to Architectural Lighting. But Lockley reached out to Money to explain that his advice "only applies to light at night if people are trying to sleep at night – it does not apply to people trying to work at night." Lockley is firmly against the usage of red lights during the night shift, stating it's "potentially dangerous to appear to recommend approving use of red or red-enriched light for night-shift workers, making them more sleepy and more likely to have accidents."

Other research indicates that red lights improve the moods of nighttime workers and might not have the negative effects on workers that white light does. Some researchers endorse the use of amber glasses and amber or red lighting as beneficial for night-shift workers.

If there's one thing that's clear, it's that light should be kept to a minimum when people are sleeping, and if there must be some light during sleeping hours, make it red. As the American Medical Association has concluded, "exposure to excessive light at night, including extended use of various electronic media, can disrupt sleep or exacerbate sleep disorders, especially in children and adolescents."

"This effect can be minimized by using dim red lighting in the nighttime bedroom environment," the AMA stated.