No matter what time of year it is, our bodies require sunlight to make something called Vitamin D, a steroid hormone that plays a pivotal role in helping us feel our best- and affects so many aspects of our health. Sunlight- specifically in the morning, also helps to release Cortisol, another steroid hormone that plays a role in our stress response, immune system and regulating metabolism. In this post I cut through the noise around cortisol, sunscreen, skin cancer and how to prevent Vitamin D deficiency. I’m going to breakdown what it all means and why maintaining your Vitamin D level alongside appropriate doses of daily sun exposure is one of the most important markers of health.
Vitamin D & Optimal Levels
Sunlight does more than help you wake up—it also helps your body produce Vitamin D3 (also called Vitamin D). When UVB rays from the sun reach your skin, they trigger a natural process that produces Vitamin D3—a nutrient important for your bones, immune system, and overall well-being. Vitamin D3 is eventually converted in the liver to 25-hydroxyvitamin D [25(OH)D], also called Calcidiol which is the circulating storage form of Vitamin D, most commonly measured by blood tests. Once needed, your kidneys convert Calcidiol to 1,25(OH)2D also called Calcitriol, the active hormone form that your body uses.
Vitamin D is vital for:
- Regulating the sleep-wake cycle (Vitamin D has receptors in the brain responsible for sleep regulation, meaning Vitamin D is associated with better sleep quality. Exposure to early sunlight helps to synchronize your circadian rhythm, promoting more restful, deep sleep at night.
- Lowered Vitamin D= lowered Serotonin levels: vitamin D plays a significant role in our mental health, and lowered levels have been associated with mental health disorders like depression, anxiety, and Seasonal Affective Disorder (SAD)
- Low Vitamin D is also linked to higher risk for chronic diseases, including heart disease, diabetes, autoimmune conditions, and more.
- Vitamin D affects your bones and muscles because vitamin D enhances absorption of calcium and phosphorus, so without it you’re left feeling achy, sore and more likely to experience a bone fracture.
How much Vitamin D Do You Need & How To Get It
- The general recommended daily intake of Vitamin D from food sources, sunlight, etc. is around 600- 800 IU daily for adults whose Vitamin D level is within normal limits (see Vitamin D blood test ranges below).
- You can achieve this by going outside for about 10-20 minutes daily during peak UV Index (when the sun is emitting the most UV rays, between 10am-2pm). On a cloudy day you’d need to double that time. Expose as much skin to the sun as you can for those 10-20 minutes, and after that applying a clean sunscreen with minimal chemicals is recommended OR going in the shade/wearing a cover up to prevent burning is also smart.
- The goal is to get a tan- NOT to burn, burning is associated with an increased risk in skin cancer while being tan is a good indicator that your vitamin D level is healthy and optimal.
- Outside of sunlight, you can get Vitamin D from egg yolks, red meat, liver, fatty/oily fish, mushrooms, and supplementation. Make sure when you purchase Vitamin D supplements you find one that includes Vitamin K, because Vitamin D increases Calcium absorption, but Vitamin K tells the body where to put that Calcium (directing it towards bones, teeth, etc.).
- Before supplementing, I would highly recommend talking to your doctor about getting your Vitamin D tested to find out what level you’re at and what they’d recommend for supplementation guidelines.
- I personally take anywhere from 5,000 IU – 10,000 IU in the late fall/early winter, starting around end of September through April or May depending on sun exposure because I am particularly prone to developing intense SAD (Seasonal Affective Disorder) in the colder months. Like any supplement- you CAN overdue it, so get your levels checked before supplementing.
- I would also recommend that if you’re vitamin D level is on the lower side, you take a sublingual vitamin D supplement vs a capsule or a pill- we are are better able to absorb liposomal sublingual supplementation vs capsule/pill form given our digestive system.
- What is the ideal Vitamin D level?
- A blood test for 25-hydroxyvitamin D [25(OH)D] is the best way to know your Vitamin D level and most health experts recommend aiming for:
- 30–50 ng/mL for general health (safe and sufficient)
- 50–70 ng/mL for optimal immune function or in special conditions
The Science akaWhy Does Morning Sunlight Matter
Getting outside within 90 minutes of waking (or at the latest before 11am), exposing your eyes and skin to sunlight, helps trigger an early release of cortisol. You might be thinking, “Wait—isn’t cortisol bad?” Not necessarily!
Cortisol is often called the “stress hormone” and is released in a fight-or-flight response, but it also plays a critical role in:
- Regulating your sleep-wake cycle (circadian rhythm) by increasing alertness in the morning when cortisol is at its peak and slowly decreasing throughout the evening, promoting sleepiness.
- Balancing blood sugar and blood pressure through controlling the release of blood sugar and increasing cardiac output, increasing blood flow and blood pressure.
- Supporting metabolism: during stressful times, cortisol provides the body with a quick energy boost by mobilizing glucose (blood sugar) to prepare for action.
- Reducing inflammation: Cortisol modulates the activity of immune cells, acting as an anti-inflammatory mediator when released in moderate- amounts.
A healthy, short-term cortisol spike in the morning—alongside other energizing hormones like dopamine and norepinephrine—tells your body: It’s time to wake up! This hormone combination that happens in the morning leads to feelings of alertness, energy and productivity. Sometimes you might find that you wake up before your alarm- this is due to a cortisol spike that happens to every one of us early in the morning. The goal is to encourage a cortisol spike right as you wake up- as this helps decrease melatonin, the hormone that makes you sleepy. Short form cortisol spikes are healthy- and do not cause any inflammation, however, chronically high cortisol levels contribute to inflammatory responses.
How to Do It:
- Aim for spending 5–10 minutes in direct morning light outside (ideally within 90 minutes of waking).
- If it’s overcast, extend this to about 20 minutes.
- Try to do this without sunglasses, glasses, or contact lenses so your body can fully absorb the light through your eyes and skin.
- If you truly can’t get outside, you could: workout, sit by an open window, cold plunge, or sip a caffeinated drink to achieve that same cortisol spike.
Beyond Morning Light: Sun Exposure During the Day
Just an FYI- it’s also a good idea to get evening/afternoon sunlight exposure as well. Even for short bursts- like a quick 5 minutes- can tell your body what time of day it is and help you fall asleep quicker by sending affirming signals to your brain about what time of day it is. We lose this when we stay indoors all day, which is why sometimes if you are sick for a few days and can’t go outside, you might be tired but wired, unable to fall asleep, as your body doesn’t know what time it is.
Ready to Go Deeper?
This is just the start. Over time, we’ll explore each of the 8 Pillars of Physical Wellbeing so you can build a strong, resilient foundation for a healthy mind, body, and life.
Stay tuned—and remember, sometimes the most powerful step forward is simply returning to the basics. Disclaimer: none of my blogs are intended to diagnose or treat anyone- I am simply providing education I’ve learned over the 13 years I’ve been in healthcare, my Functional Medicine Health Coaching Program and throughout my own health and wellness journey. I believe preventative medicine should be free and accessible to everyone- so this is my contribution to that cause. I hope you enjoy! Thanks for tuning in.
Sources
https://pmc.ncbi.nlm.nih.gov/articles/PMC5440113
https://www.hubermanlab.com/newsletter/using-light-for-health