Lightscapes, nightscapes and glowing screens— how light effects our health and genes
Ah, light. The ubiquitous radiation that bombards our humble human bodies. Multiple wavelengths of vibrating photons that illuminate our world. The wonderful, yet minute, visible spectrum that we can detect and the invisible, hidden ranges that slip past our primitive senses.
Light is all around us.
From the incandescent glow of city street lights to the blue glow of our electronic screens — light follows us throughout the day and into the night. Something so commonplace and pervasive lulls us into a sense of safe serenity.
Light is warm and comforting. Light is our friend.
Of course, we are aware of the devastating effects of the sun’s blitzkrieg of unforgiving UV rays. The ones that ravage our skin — causing our epithelial cells to make mistakes, mutate, and replicate unchecked —often leading to proliferation as the common carcinoma or the insidious melanoma.
Light kills. Light destroys.
Light giveth and light taketh it away.
The harsh light of day
Let’s start with the sun— the gaseous orb sizzling in the sky above our heads.
An assortment of energy is currently raining down upon the earth.
Plants absorb it and cultivate their own energy from it and it warms our skin as we bask in it.
There, in our skin, a little molecule awaits the sun’s light to change its shape. This is the precursor to vitamin D — the “sunshine vitamin”— necessary to maintain many biological functions. Our immune system and equilibrium of the minerals within our bone rely on this molecule.
Without it, we begin to crumble.
Rickets — a disease characterized by softening and degradation of the bones— occurred frequently in 19th century urban children of Europe who, with industrialization, had infrequent exposure to the sun. Weakness, pain and decreased density of the bones lead to a debilitating disease that caused poor mobility and deformities.
Incidence of rickets declined over the 20th century when a correlation between sunlight and the disease was drawn by the medical community. (Although, not gone nor forgotten, rickets still lurks and lingers in populations to this day.)
Sunbathing soon became the prescription to cure and prevent ill health.And to this day, the beguiled nature of the sun’s warmth still leads many to bask in it’s glory.
What is better than the beautiful warmth of ultraviolet light catching our skin a blaze.
Ultraviolet light—the wavelength needed to get the vitamin D precursor vibrating —along with, X Rays and infrared light, are part of the electromagnetic radiation that is emitted from the sun. Radiation that is constantly raining down on our skin, lulling us to sleep with its warmth.
In our sunscreen culture, it is widely known that UV light can be dangerous. It gets its sunlit fingers inside our DNA and mucks about — supercharging the molecules with it’s gooey golden energy.
Our DNA can take quiet the wallop of additional energy without any real repercussions but, if exposed for long enough, things can start to falter.
It gets tired. It gives in.
DNA consists of a sugar backbone, phosphate molecules and a very important nitrogenous base — either a pyrimidine or purine. If two pyrimidines are next to each other —thymine or cytosine — an extended barrage of UV light can lead to the two molecules fusing together.
Something called dimerization.
The two bases become linked to each other, creating a ringed structure. This contributes to an unstable intermediate molecule which can put a literal kink in the transcription of proteins— a key part of cellular processes— by changing the shape of the DNA’s backbone.
UV light can also indirectly affect DNA, with the creation of reactive oxygen species, better known as free radicals. Free radicals, act a little bit like a Viking horde — raiding and ravaging molecules for electrons. leading to mutations that can add up during DNA replication.
Tiny infractions lead to the swapping of base pairs and create a mess of the once pristine code, often producing nonsense sequences. Nonsense sequences lead to nonsense (defective) proteins which, in turn, lead to phenotypic mutations and often times disease.
Fortunately, we have repair mechanisms that scan the length of our DNA. They remove and replace the mistakes before the wound is sealed behind it. Sometimes, however, these mutations are missed or go unchecked and the result can lead to some serious, prolific consequences.
Light, itself can also change gene expression, leading to substantial changes in our body’s regulation.
And it’s not just sunlight tickling the melanin cells within our skin long enough to produce monstrous melanoma. It occurs on a much smaller, more subtle scale that we are only beginning to understand.
And most of it starts in the palm of your hand or the comfort of your lap.
Bathing in the Beguiling Blue Glow
The light your phone or computer emits is unique compared to the sunlight that trickles in through your windows. The wavelength is shorter and this is the reason for that familiar blue tint.
This has a direct effect on specific genes. The ones that regulate the production of melatonin and put “the rhythm” in our circadian rhythm.
The circadian rhythm is a network of interconnected mechanisms working together to influence specific, timed functions inside your body. It controls the cycle of hormone production and release, metabolic pathways and maintenance of proper cellular function.
The circadian rhythm is not unique to humans, in fact, even bacteria have a circadian system. It appears to be an important, well conserved mechanism across both eukaryotes and prokaryotes.
However, unlike bacteria, humans have a circadian pacemaker hidden inside our hypothalamus called the suprachiasmatic nucleus. It has its hand in signaling the production of the hormone melatonin and for sending out neural signals in response to light and other inputs.
It keeps everything in line and on time
Many important physiological functions rely on this train conductor — and its well timed, 24 hr pocket watch —for things to run smoothly.
Although there may be several factors that have an influence on the clock, light is one that plays an incredibly important role.
It is critical at keeping the rhythm from oscillating and It all starts with your eyes.
Windows Let the Light In
Taking a deep dive inside the vitreous humour, towards the very back of your eye, you can find your retina.
The retina is home to many light sensitive neurons called ganglion cells. These cells are particularly excited by blue light and they send crackling messages blazing straight to your hypothalamus.
There, they poke at that little pacemaker in charge of keeping everything in order.
This bombardment of light and excitation disrupts melatonin production which, in turn, throws the rhythm from the tracks — effectively derailing the clock.
Now, the beguiling blue light may be quite innocuous when you assault your retinas with glowing screens in the day time hours. However, when you stare at glowing pixels in a darkened room at night, you find yourself actively sabotaging your rhythm and sending a big, glaring stop light to hormone production.
A decrease in melatonin is not just detrimental to your ability to sleep and your mood regulation, it has systemic implications on physiological functions throughout the tissue and cells of your body. Like the methodical tumbling of a set of dominos — the effects are compounding.
Metabolism is negatively affected and there are discrete endocrine implications. This is especially apparent in altered glucose metabolism and insulin sensitivity. This may put an individual at increasing risk for obesity, type two diabetes and metabolic dysfunction.
Studies on circadian rhythm disruption also found elevated blood pressure and increased risk for cardiovascular disease and stroke. This seems to be related to modifications of neurotransmitters, lipid metabolism and a increase in oxidative stress due to sleep deprivation.
The body does not work insolation. It is an interconnected, intertwined system — an elegant ballet that requires rigorous, finely tuned footwork from all its players.
It does not function alone and cannot survive alone.
When things fall out of sync and the orchestra is suddenly out-of-tune, a cascade of failures tend that occur.
The Dark Side of Light
And It all comes back to light. The photons of light that bounce off our skin and beam into our eyes directly affect the tiniest mechanisms in our body.
It can turn a gene on or turn one off.
These simple switches of transcription factors — molecules that bind to lengths of our DNA and control the information that is transcribed — have huge physiological impacts.
Artificial light, streaming from our devices in the darkness of the night, appears to have a direct influence on the smallest molecules in our body. It has the power to influence our genetic and phenotypic expression, our metabolism, our cell cycles and, in turn, our health. It appears we are ever unaware of the power and influence our environment has on our fallible bodies.
Light— pulsating invisible atoms— can alter us in ways nearly unimaginable.
I am a big subscriber to the thought that “you are your brain”.
That the very things that make you who you were, who you are and who you’ll become lie inside the squishy sulci of this gelatinous organ. You rely on the thing staying intact and with all systems firing. If something comes along and mucks about inside of it — injury, microbe, mutated proteins, etc. — you cease to be you.
However, it’s appears to be more nuanced than that. That something as ubiquitous as light, can reach inside and play around with our DNA — effectively changing our physiological functions and phenotypes — with some fair reaching and sometimes negative consequences.
It illustrates the balance of the entire system. That everything needs to be in rhythm, on time, flowing and tumbling together. That who you were, who you are and who you’ll become depends on the synchronicity of a trillion molecules.
Ones that are both inside you and outside of you— tumbling through the great, wild and indifferent universe.