Studies into how light affects our circadian rhythms and by extension can be used to treat Seasonal Affective Disorder are continually underway and revealing how different wavelengths may be more efficient than others. A recent study into these wavelengths of light has questioned ‘How effective is Orange Light in particular in possibly treating SAD?’.
As light therapy treatments have been shown to be effective in helping to treat Seasonal Affective Disorder, predominantly in the full-spectrum of white light and in the less intensive, but more effective blue light wavelength it stands to reason that other singled out colours may also impact melanopsin production.
In 2014, Gilles Vandewalle and his team began studies at the University of Liege in Belgium into exactly how melanopsin is able to wake up the brain. This was done by exposing a group of sixteen people to either blue or orange light for ten minutes before taking part in a memory test whilst being monitored in an fMRI scanner. Afterwards the participants were blindfolded for an hour and ten minutes and then given the test again after being exposed to green light, which is besides being between both colours in the full spectrum, also lies in the middle in terms of making the pigment of melanopsin more light sensitive with orange being the most effective. The results showed that Orange light caused more activity in regions associated with cognitive function and alertness.
It should be noted that previous studies and real-world use of Blue Light SAD therapy lights has shown to be very effective in increasing alertness and helping to normalise the body’s circadian rhythms. The study does show that light does have non-visual responses for the cognitive functions in the brain through melanopsin, though the responses in the photoreceptors were not definitively seen.
So there is definitely a correlation between the various wavelengths of light and cognitive function, particularly in the orange range in addition to white and blue. This means that orange light may well be effective in treating SAD in a similar way as other light therapy boxes and boosting alertness through making a more light-sensitive type of melanopsin. Further study in the future should discover the various roles that light wavelengths play in brain function and circadian rhythms.
You can view the study reference here.