New research has shown that blue light may not be as disruptive to human sleeping patterns as previously thought.
According to a team of scientists from the University of Manchester, using dim, cooler lights in the evening and bright warmer lights in the day may be more beneficial to our health.
Research shows that twilight is dimmer and bluer than day light. Researchers say that the human body clock uses both of those features to determine the appropriate times to rest.
The current technologies designed to limit our evening exposure to blue light, often by changing the screen colour of cellular phones, may confuse the natural responses to light. Researchers hypothesised that this is because the small changes in brightness that they produce are accompanied by ‘day’ colours.
The Manchester based research team carried out their study on mice, using specially designed lighting that allows the team to adjust colour without changing the lights brightness.
Research showed that the blue lights presented a lesser effect on the mouse than the equally bright yellow light. This has important implications for the design of lighting and visual displays intended to ensure healthy patterns of sleep and alertness.
Published in Current Biology, the study highlights that the body clock uses light sensitive proteins, located in the eye, to measure brightness. Called melanopsin, these proteins are better at detecting shorter wavelength photons.
Dr Tim Brown, from The University of Manchester, said: “We show the common view that blue light has the strongest effect on the clock is misguided; in fact, the blue colours that are associated with twilight have a weaker effect than white or yellow light of equivalent brightness.
“There is lots of interest in altering the impact of light on the clock by adjusting the brightness signals detected by melanopsin but current approaches usually do this by changing the ratio of short and long wavelength light; this provides a small difference in brightness at the expense of perceptible changes in colour.”