Did you know that fat cells or adipocytes located beneath the skin possess the ability to perceive light? Yes, it is true, scientists have found that the adipocytes behave differently when your bodies do not get adequate exposure to the proper kinds of light.
A team of scientists led by Richard Lang, Ph.D. was studying how mice regulate their body temperature. What they found has consequences that go far beyond discussing how warm mice remain.
Exposure to light regulates two kinds of fat cells to work in conjunction and supply raw materials to be used by all other cells for energy. Inadequate light exposure disrupts this basic metabolic process which represents an unhealthy aspect of spending too much time indoors.
“Our bodies evolved over the years under the sun’s light, including developing light-sensing genes called opsins,” says Richard Lang. “But now we live so much of our days under artificial light, which does not provide the full spectrum of light we all get from the sun.”
Lang, directs the Visual Systems Group at Cincinnati Children’s, his research is focused on eye development and the light’s engagement with cells beyond the eye.
“This paper represents a significant change in the way we view the effects of light on our bodies,” Lang says.
Notwithstanding the fact that some light wavelengths, like gamma and ultraviolet radiation, can be harmful, current research has shed some light on a different and healthy role for light exposure.
Light can penetrate the fur of a mouse or the clothes worn by a person and enter our bodies. According to Lang, photons-the basic unit of light, may slow down and scatter around on having penetrated the external layers of the skin. Upon entering the bodies, the photons affect the behavior of cells.
In 2013, Lang led a study published in Nature, on How exposure to light in fetal mice influenced eye development. Recently in 2019, Lang and his team reported possible implications of phototherapy in preterm babies for eye growth, and another study on how light receptors in the skin help mice control clocks within.
The latest study has been published in Cell Reports.
“This idea of light penetration into deep tissue is very new, even to many of my scientific colleagues,” Lang says. “But we and others have been finding opsins located in a variety of tissue types. This is still just the beginning of this work.”
The current findings by the research team revealed how mice react to chilly temperatures of around 40° F. Similar to humans, mice too use both a shivering response and an internal fat-burning response to warm up themselves.
A more in-depth analysis revealed that the internal heating process is compromised in the absence of the gene OPN3 and when there is not enough exposure specifically to a 480 nm wavelength of blue light (which is naturally a part of sunlight but occurs only in insufficient levels in most artificial light).
On exposure to appropriate light, OPN3 causes white fat cells to release fatty acids into the bloodstream to be used by several kinds of cells as energy to fuel their activities. On the other hand, brown fat oxidises the fatty acids producing heat that warms up the chilly mice.
It was observed that under chilly conditions, the mice that were bred to lack the OPN3 gene, did not warm up as much as the mice which possessed the OPN3 gene did. However, surprisingly even mice that expressed the right gene did not warm up when exposed to light that lacked the blue wavelength.
Based on this data, researchers reached the conclusion that sunlight is necessary for normal energy metabolism, in mice at least. Researchers strongly suspect the presence of a similar light-dependent metabolic pathway in humans, though research is required to prove it.
“If the light-OPN3-adipocyte pathway exists in humans, there are potentially broad implications for human health,” the study states. “Our modern lifestyle subjects us to unnatural lighting spectra, exposure to light at night, shift work, and jet lag, all of which result in metabolic disruption. Based on the current findings, it is possible that insufficient stimulation of the light-OPN3-adipocyte pathway is part of an explanation for the prevalence of metabolic deregulation in industrialized nations where unnatural lighting has become the norm.”
Several years of study might be required to exposit this discovery.
We are hoping that maybe someday, in theory, “light therapy” could offer a way to prevent metabolic syndrome from developing into diabetes says, Lang. The replacement of indoor lights with better, entire spectrum lighting systems could also improve public health, according to Lang.
However, to evaluate the potential therapeutic benefits of phototherapy, further research is needed. There are many queries that are yet to be answered. Some of these are deciding the amount of sunlight required to support a good metabolism, and whether people suffering obesity can lack a functional OPN3 gene in their fat cells. Also, unknown: when would light therapy is more effective: for pregnant women? For babies and children? Or for fully developed grown-ups?
For now, however, “if people want to take anything personal away from this, you likely can’t go wrong by spending more time outside,” Lang says.