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Research scientists at the University of Manchester have found that the colour of light has a major impact on the body clock of mice and other mammals such as humans.
This is the first time that the impact of colour has been tested. The results of this new study have shown that the colour of light is a more reliable means of measuring time, rather than measuring brightness.
The researchers observed the vartiation of light during dusk and dawn in order to investigate if the time of the day can be determined examining the colour of light. Apart from the light intensity changes which occur during the sun rise and sun set, the scientists also observed that light is bluer during twilight than it is during the daytime.
The electrical activity in the body clock of mice was then recorded by the researchers. The results of electrical activity in mice were found to have different visual stimuli. In addition, it was revealed that most of the cells were sensitive to colour changes, particularly between blue and yellow rather than to changes in brightness.
The scientists developed an artificial sky in order to recreate the day-to-day changes in brightness and colour using the measured changes in the colour spectra captured from the top of the Pariser Building at the University of Manchester.
This is the first time that we’ve been able to test the theory that colour affects the body clock in mammals. It has always been very hard to separate the change in colour to the change in brightness but using new experimental tools and a psychophysics approach we were successful.
Dr Timothy Brown - Faculty of Life Sciences, University of Manchester
Following this, the mice were kept below the artificial sky in order to record their body temperatures. As expected, the highest body temperatures for nocturnal creatures appeared when the sky turned into dark blue colour immediately after the night fell. This indicated the optimal performance of the body clock of the mice.
Upon observing a change in the sky brightness without a change in the colour, the mice became dynamic prior to dusk. This demonstrated the non-alignment of the body clock with respect to the day night cycle.
What’s exciting about our research is that the same findings can be applied to humans. So in theory colour could be used to manipulate our clock, which could be useful for shift workers or travelers wanting to minimize jet lag.
Dr Timothy Brown - Faculty of Life Sciences, University of Manchester
The research was published in the Open Access journal PLOS Biology.