Who needs coffee in the morning when you can just shine an orange light in your eyes? A team of European scientists has shown that exposure to an orange light improves alertness and cognitive brain function.
Light, both natural and artificial, affects our circadian rhythms, causing alertness and sometimes upsetting our sleep patterns. Scientists believe this physiological interaction with light acts through the body’s photoreception system, which relies heavily on a recently discovered light-sensitive cell or photopigment called melanopsin found within the eye. These cells work separately to the rods and cones needed for vision.
Previous research on animals in the last few years has shown that, if melanopsin is absent, non-visual functions are disrupted. Their built-in biological clock becomes deregulated and ‘free runs’ independent from day-night cycles, and light no longer has a stimulating effect.
Researchers from the University of Liège, Belgium, and INSERM Stem Cell and Brain Research Institute, France, wanted to find out how melanopsin affects the human brain, what effect different wavelengths of light had on melanopsin and how this influences executive brain responses – cognitive brain functions such as anticipation, working memory, sequencing (breaking tasks into smaller units and ordering them), problem-solving and decision-making – and alertness.
The researchers put 16 young and healthy test subjects through a week of regulating their sleep/wake patterns (with approximately 8 hours of sleep each night). On the days of the experiment, participants arrived 2 hours after waking and were exposed to white light for 5 minutes to standardise their light history. The subjects than underwent consecutive and identical functional magnetic resonance imaging (fMRI) scans, during which they performed a simple auditory detection task and a more difficult auditory working memory task while continuously exposed to the same test light (green light at 515 nm).
Just over an hour before each recording, the subjects were exp