How Does Light Affect Our Bodies?

Oct 11, 2021 | Human Centric Lighting

Humans are blue-sky creatures; we work best in daylight. In this blog we will discuss and examine the ever-growing list of ways how light affects our bodies and can improve (or worsen) our lives.

Exposure to light can affect us in many ways; it helps regulate hormone production among other functions which influences our mood, sleep, sex drive, appetites, and much more. Acquiring a better understanding of light’s effects on our body processes can give us the means to make positive changes that can transform nearly every realm of our lives. Sometimes, the key to improving your day-to-day life is as simple as turning on the right kind of light.

Light and the body

How Does Light Enter Our Bodies?

Light enters our bodies in two ways; via skin exposure, or through our eyes.

The visual process begins as light passes through the cornea and into the lens of the eye. Then the cornea and lens in conjunction help to focus the light on the retina, the back of our eyes, which absorbs and then converts light into electrochemical impulses. These electrochemical impulses travel along the optic nerve and arrive in our brains. In turn our brain converts these impulses into the images you see. This process happens in fractions of a second.

Skin exposure to daylight is particularly important to our hormonal regulation. While some aspects of light-to-skin exposure are still unclear, we do know that many body processes, including our sleep schedule and ability to absorb certain vitamins, are regulated by this sort of light exposure (and we’ll get into the known mechanisms of these processes below).

Exposure to differing varieties of light in differing ways (from eyesight to skin exposure) triggers a variety of hormonal responses, which affect everything from our mood, productivity and cortisol production to our sleep cycle, appetite, and ability to absorb vitamins.

Light’s Affect on Vitamin Absorption

Many of us are aware that we manufacture vitamin D in our bodies via sun exposure, but unfortunately many of us do not receive nearly enough sun to create suitable amounts of vitamin D. Another way how light affects our bodies is when our skin is exposed to sunlight it begins to manufacture vitamin D as it has for thousands of years; but nowadays we are not nearly as exposed as we once were.

The chemical process of vitamin D synthesis is surprisingly simple. Ultraviolet-b rays from the sun spark a chemical domino effect in your skin; keratinocyte cells are prompted by sunlight to produce vitamin D-3, an inactive form of vitamin D. The D-3 vitamin then travels to your kidneys and liver; in the process, it picks up extra oxygen and hydrogen molecules and transforms into the bone-building, immune-boosting vitamin D we’re familiar with.

Our changing world dictates that many of us now spend significantly less time outside, and this leaves a large portion of our population vitamin D deficient. This is problematic, as this deficiency can lead to a loss of bone density and in turn osteoporosis. Vitamin D deficiency is also linked to issues with fatigue and mental health and is also suspected to factor into immune system function as well- making it one of the most vital vitamins our body synthesizes.

Vitamin D deficiency is a creeping threat in today’s modern world, but it can be mitigated with artificial light that is spectrally optimized. Sun lamps or light boxes are lighting fixtures that stimulate vitamin D production by imitating sunlight and are easily placeable in the home or office. It’s a small step you can take to prevent an all-too-common deficiency.

Light’s Affect on Our Moods

Light also has a direct effect on two of the most important hormonal processes of our day-to-day lives; our serotonin and cortisol production.

Serotonin is an important neurotransmitter chemical that is often referred to as the “happy” hormone. It directly contributes to our mood and psychological processes, and in turn our overall physiological health. We don’t know exactly how light exposure triggers serotonin production (some scientists believe the skin is a major manufacturer of serotonin building blocks), but it does- and too little sun can lead to a dip in serotonin production, resulting in conditions like Seasonal Affective Disorder, or SAD, and can contribute to poor mental and emotional health.

Cortisol is a steroid hormone that is responsible for alertness and wakefulness during daytime hours. It is released by the adrenal glands, which sit on top of the kidneys. Daylight ignites the release of cortisol, but too much cortisol isn’t a good thing- it puts great stress on the body, causes weight gain, mood disturbances, high blood pressure, and can even lead to a disease called Cushing’s Syndrome. it should be noted that exposure to blue light at night can disrupt the natural release of cortisol, resulting in increased stress.

Inadequate sunlight exposure slows our bodies production of these hormones, so it’s recommended you get at least 30 minutes of sunlight a day to prevent low serotonin and cortisol production, and limit sunlight mimicking blue light at night (like that found on your phone screen or other electronic devices).

However, there is good news for those of us who struggle to find the time to receive adequate exposure; artificial light, specifically blue light, can produce the same effect in regulating serotonin and cortisol production, and just like a vitamin D deficiency, this can be corrected with a light box.

How Light Affects Our Sleep

Our sleep, much like our mood, is regulated by hormones as well. Melatonin is the hormone responsible for prompting the feeling of sleepiness, but for many of us our melatonin production is being suppressed by too much exposure to blue light, especially at night (thanks to our use of electronics and artificial lighting). Blue light is commonly produced by TV’s, cell phones, and computer screens, so limiting their use at night is paramount to a good night’s sleep.

This is because blue light, whether artificial or from the sun, tells our bodies it’s time to be alert and awake, which at night disrupts several our biological processes, leading to poor sleep. Poor sleep can have disastrous knock-on affects when it comes to our health- it is known to worsen cardiovascular health and is even associated with early death.

Light’s Affect on Appetite

Studies out of Cambridge University in the UK have recently shown that light can affect even our appetites. The hormones leptin and ghrelin are responsible for hunger and the desire to eat. The Cambridge studies showed significant differences in relative hunger and the desire to eat based upon whether the subjects were exposed to dim lights or bright lights. Those exposed to dim light, mimicking evening time, had a measurable decrease in hunger, and those exposed to bright experienced the opposite. The study results suggest melatonin may contribute to appetite as well.

While the science around appetite and light is still developing, it makes sense that it seems to be strongly correlated to our light exposure and the other light-based rhythms of our bodies.

Light’s Affect on Productivity

Much of the above mentioned processes directly affect our productivity– who can write a paper when they’re sleepy, hungry or stressed, after all? Studies have shown that those who are not exposed to a good amount of natural light are more likely to see a drop in productivity.

Furthermore, research published by Eco Business has shown that workplaces with sufficient daylight saw a rise between 5-40% in productivity. With light’s significant effect on our ability to produce important mood and health-regulating hormones, it makes perfect sense that such a change in productivity could take place. Try adding more sunlight or artificial blue light to your own workspace and see the results; there’s a reason why more businesses are opting for skylights and large windows, and it isn’t because they simply look nice!

Taking Advantage of Light Science to Improve Our Lives

All of these effects from light tend to have a meta effect. Serotonin and cortisol boosting or dampening our mood, proper melatonin production allowing us to have better or worse sleep, and better sleep assisting us in regulating our appetite. These effects compound, so instead of tolerating more stress, worse sleep, poor appetite, and a bad mood, we should look to change our environment. Thankfully, modern technology makes this easier than ever to accomplish.

How to Improve Your Lighting Environment

One of the easiest things to change is our exposure to light. If you work from home, pull up the blinds and if possible, move your workstation or desk to a window that receives natural daylight. If you’re limited by your cubicle at work, consider adding a lightbox to your desk or home (the SkyView table wellness lamp is one option!) that will boost productivity. It’s also important to make sure specific spaces in your home are lit appropriately; bedrooms should use warm, longer-wavelength light to stimulate melatonin production and prepare you for sleep.

Above all else you should spend more time outside, and try to follow the natural light patterns of the planet. Daylight exposure- whether that’s walking in the morning to get your coffee instead of going through the drive-thru, or reading in a park on the weekend instead of catching up on Netflix- can boost your health in myriad ways, as can removing blue-light sources from your home at night time. There are numerous ways to attain the advantages of light exposure, and your body will thank you for it.

FAQs

  • What can I do to optimize my light exposure?

You should spend more time outside or exposed to bright light in the daytime and less time on screens at night.

  • How does light affect our sleep?

Blue light at night, produced by electronic objects like phones, TVs, and computers, suppresses melatonin production, the predominant hormons associated with feeling ‘sleepy’. This results in poor sleep quality, and trouble falling asleep.

  • Can certain lighting make someone more productive?

Yes, research has shown that sufficient sunlight or blue light exposure results in a large increase in overall productivity.

  • Does light really affect our overall moods?

Yes, light exposure directly influences serotonin, and cortisol production. Both hormones are responsible in regulation of our overall mood.

  • Should I be receiving more light to compensate for Daylight Savings?

Yes, during this time we receive significantly less light than usual and should look to add to our diminished exposure; ideally, this can be done by utilizing a lightbox.