The Health Pyramid- Level 2- Sunlight

SUNLIGHT

Your Body Was Designed to Know When the Sun Comes Up

I think sunlight is one of those parts of health that most of us know is important, but we don’t necessarily understand just how much our bodies are paying attention to it. We think about sunshine when we think about summer, being outside, getting a tan or maybe vitamin D, but light is actually information. From the moment we wake up, light is one of the signals our brain uses to figure out what time it is and what our body should be doing.

That is why I included sunlight in Level 2 of my Health Pyramid. It may seem almost too simple to belong in a conversation about health, but sometimes the things that seem the simplest are influencing far more than we realize.

Your Eyes Are Doing More Than Seeing

When morning light enters our eyes, specialized light-sensitive cells in the retina send signals to an area of the brain called the suprachiasmatic nucleus, or SCN. You can think of the SCN as the body’s master clock.

That clock helps coordinate our circadian rhythm, the roughly 24-hour biological cycle that influences when we feel awake, when we feel sleepy, hormone release, body temperature, metabolism and many other processes throughout the body.

This is one of the reasons getting outside in the morning can be so valuable. You aren’t just getting fresh air. You’re giving your brain an important time-of-day signal. Morning light helps tell your body, essentially, the day has started.

As the day progresses and eventually becomes dark, the change in light helps your body prepare for nighttime. Melatonin, a hormone involved in signaling biological night, normally rises in dim-light conditions in the evening.

This is also why our modern environment can make things complicated. We can spend the morning inside relatively dim buildings, barely see natural daylight, and then surround ourselves with bright artificial light and screens late into the evening. Biologically, those aren’t necessarily the signals our internal clocks evolved around.

Then There Is Vitamin D

Sunlight has another very different relationship with our health: UVB radiation from sunlight can trigger vitamin D production in our skin.

Vitamin D is often called a vitamin, although biologically it behaves more like a hormone in many ways. It is involved in calcium and phosphorus regulation and is important for bone and muscle health. Vitamin D receptors are found throughout the body, and researchers continue to study its broader roles.

What I find especially interesting is how much geography matters.

I live in Maine, where winter sunlight is very different from what someone experiences living much farther south. At northern latitudes, particularly during the colder months, the angle of the sun can substantially reduce the amount of UVB available for vitamin D production. Add shorter days, cold weather, layers of clothing and the fact that many of us spend much more time indoors, and it isn’t difficult to understand why vitamin D status can become something worth paying attention to.

I know this personally because my vitamin D levels tend to run low. It is something I monitor with my healthcare providers, and I currently receive vitamin D injections as part of my own care.

That does not mean injections are something everyone needs, or even that everyone with a low vitamin D level needs them. There are different ways vitamin D deficiency or insufficiency may be addressed, and the appropriate approach depends on the person, their bloodwork, medical history and the reason their levels are low. But it is a perfect example of why I believe in testing instead of guessing.

What If You Aren’t Getting Enough Sunlight?

This is where I think the conversation becomes practical, because “get more sunlight” sounds great until it is January in Maine, you leave home when it’s dark and it feels like the sun is setting before you’ve finished your afternoon coffee.

There are still things we can do.

• Get outside early when you can. Even on an overcast day, outdoor light is generally much brighter than typical indoor lighting. Morning outdoor light can help reinforce your circadian rhythm. You don’t need to stare at the sun, and you shouldn’t. Simply being outside and allowing normal daylight to reach your eyes can provide a light signal.

• Open the blinds and make your mornings brighter. Natural outdoor light is preferable when practical, but creating a brighter daytime environment can still help distinguish day from night.

• Consider appropriately designed light therapy when necessary. Bright-light therapy devices are commonly used for seasonal affective disorder and circadian-related purposes. A common clinical light box provides around 10,000 lux, but timing and duration matter. More is not automatically better. Light therapy may not be appropriate for everyone, particularly people with certain eye conditions, light-sensitive medical conditions, bipolar disorder, or those taking medications that increase photosensitivity, so this is something worth discussing with a healthcare professional when appropriate.

• Have your vitamin D checked if there is a reason to suspect it may be low. Vitamin D status can be evaluated with a blood test called 25-hydroxyvitamin D. Rather than automatically taking very high doses because you live somewhere cold, testing gives you and your healthcare provider actual information to work with.

• Supplement when appropriate. Vitamin D supplements are widely available and may be recommended when dietary intake, sun exposure or blood levels indicate a need. The amount needed varies, and taking excessive vitamin D can be harmful because it is fat-soluble and can accumulate in the body. This is one of those situations where more is definitely not always better.

Sunlight and Vitamin D Are Related, But They Aren’t the Same Thing

This is an important distinction. Taking vitamin D does not replace the circadian effect of morning light. And getting morning light does not guarantee that your vitamin D level is adequate.

They are two different biological pathways that happen to involve the sun. Your eyes are helping your brain understand when it is daytime. Your skin can use certain wavelengths of ultraviolet light to begin producing vitamin D. Both matter, but for different reasons.

That was something I didn’t always think about. It is easy to reduce the entire conversation to “sunlight gives us vitamin D,” when the relationship between light and our bodies is much more interesting than that.

But What About Skin Cancer?

We can’t have an honest conversation about sunlight without talking about this side of it too.

There is a difference between recognizing the biological importance of light and encouraging people to intentionally expose themselves to damaging levels of ultraviolet radiation.

You do not need to burn or tan to support your circadian rhythm.

In fact, the circadian benefits of morning light come through the eyes, not from trying to expose as much skin as possible. UV radiation can damage skin and increase skin-cancer risk, which is why sun protection remains important.

Like so many things in health, this isn’t an all-or-nothing conversation. Sunlight isn’t “bad,” and unlimited UV exposure isn’t “healthy.” The goal is understanding what different types of light are doing and making informed choices.

A Few Things to Think About

As you go through the next few days, pay attention to your relationship with light:

• How soon after waking do you actually see outdoor daylight?

• How much of your day is spent indoors?

• Is your daytime environment relatively dark?

• Are your evenings filled with bright overhead lights and screens?

• Does your sleep schedule change during the darker winter months?

• Do your mood or energy levels seem different seasonally?

• Have you ever had your vitamin D level checked?

• If you live in a northern climate, have you ever considered how the seasons may be affecting your light exposure?

You don’t need to turn your morning into another complicated wellness routine. Sometimes this can be as simple as taking your coffee outside, walking the dog in the morning, standing on the porch for a little while or taking a short walk before starting your day.

INVISIBLY EMPOWERED