Sunshine: The Healing Power of Nature

As we continue with the series Health Beyond the Plate, today we'll explore the power of sunshine and nature therapy. To help you understand what nature therapy is, I want to share real examples from my own life and the science that now explains what I experienced intuitively for years.

Growing Up Close to the Earth

I grew up in Puerto Rico, in a small coastal town on the quieter side of the island. I enjoyed having animals, walking through my grandfather's land planted with plantains, and dreaming about how beautiful life was.

Even as a child, I found myself thinking about how to make the space around me better, more alive. Sometimes I walked from school to my grandma's house and crossed through my grandfather's land. I was a good student, but most of the time I heard teachers tell my mom: "He's a good boy, but he can't sit still — he moves like he has ants in his pants!" For me, that didn't mean anything. I felt fine.

A childhood rooted in sun, soil, and sea.

My mom encouraged me to sit in the front row so I could focus, and I did. I learned, but I didn't stop moving. When I arrived home, I played outside, then did my homework. Sometimes I was running around while my mom reinforced school materials. I continued being a smart boy with good grades.

I remember going outside after studying indoors. I just felt the need to be outside.

When I entered university, I brought my notebooks to the yard and studied outside. I learned faster, retained more information, and recalled facts more easily.

Now stay with me, because science has shown there's a real reason for all of this.

A Difficult Season Away from Nature

When I entered medical school in a foreign country, I stopped spending time outside. I felt depressed, far from my home.

I remember spending many hours in a small studio apartment with two windows close to the ceiling, higher than my height. I had no view. No trees. No sky.

When I felt I needed to do something different, I played video games. I chose one where the character walks through nature and jumps over obstacles. Somehow, after playing for about 20 minutes, I could go back to studying and focus more easily.

After two years, I moved to a bigger house with windows all around, tree views, and a terrace in the back. I started running through the neighborhood. I took one full day of rest each week, went to church, and socialized more. I even went camping in the high mountains, with no technology and barely any time indoors.

In medical school, I started to have more success in every area. My life was returning to the joy of being myself.

The Science Behind Sunshine and Green Spaces

So what was happening in my body during those seasons — when I felt focused and alive outside, and depleted when I was cut off from the sky and trees? To understand why spending time outdoors is so powerful, we need to look at two things: what sunshine does directly to your biology, and what natural spaces do more broadly. Green environments bring more than just light: fresh air, diverse microbiota, natural sounds, and visual patterns that all work together to support your physiology.

Sunshine is more powerful than many people think.

Let's start with sunshine.

The Benefits of Sunshine

Your Body's Internal Clock

It may feel like sunshine simply warms you up, but it actually affects your body chemistry in profound ways. The most foundational of these is its role in regulating your circadian rhythm, your body's internal clock.

Your circadian rhythm is designed to follow the natural pattern of the planet: sun comes up, sun goes down. What makes this remarkable is that this clock doesn't live only in your brain. Virtually every cell in your body carries its own version of it.

When you expose your eyes to bright light in the morning, that light travels through your retina to a region deep in the brain called the suprachiasmatic nucleus. Think of this nucleus as the conductor of an orchestra. It receives the signal from sunlight and then sends instructions to cells throughout your entire body. When the conductor is in sync, the music your body plays sounds like this: better weight regulation, balanced hormones, and healthy thermogenesis, which is your body's ability to regulate temperature, manage energy expenditure, and guide your food intake. One practical example of this: the body is designed to process larger, nourishing meals earlier in the day, and lighter ones as the sun goes down. Working with that rhythm rather than against it supports a healthy weight (1).

The Serotonin and Melatonin Cycle

The conductor also sets off a beautiful hormonal cycle that begins the moment you step into the morning light. Serotonin levels naturally rise with sun exposure. You may know serotonin as a mood stabilizer because it is what keeps you feeling good and emotionally grounded throughout the day.

But its role doesn't stop there. If you get enough sunlight, especially earlier in the morning, your body produces enough serotonin that by the end of the day, there is some to spare. That matters because serotonin acts as a precursor to melatonin, supporting its production alongside the melatonin your body makes through its own separate pathway. Some foods also help raise melatonin levels naturally: nuts, cherries, bananas, soybeans, and others. Rather than reaching for a supplement, your body can produce its own melatonin when you've given it enough sunlight during the day. Then, when you wake up and expose yourself to light once again, the melatonin gets cleared, keeping you alert and energized. It truly is a powerful cycle.

Vitamin D

Another well-known benefit of sunlight is vitamin D, though it is worth understanding exactly how it works. When UVB rays from the sun hit your skin, they convert the cholesterol naturally present in your body into vitamin D. This happens continuously with sun exposure.

Vitamin D is essential for bone health. In children, it helps prevent rickets, a condition that causes weak, soft, or deformed bones. In adults, it helps decrease the risk of osteopenia, osteoporosis, and osteomalacia. There is also growing data suggesting it plays a role in mood stabilization and reducing depressive symptoms. It is worth noting that vitamin D behaves less like a traditional vitamin and more like a hormone in the body, influencing a wide range of biological processes.

The Benefits of Natural Spaces

Cortisol, Calm, and Your Metabolic Health

You may already be familiar with cortisol, the hormone that rises naturally in the morning to help you wake up and get going. As discussed in an earlier post, cortisol that stays elevated throughout the day, especially when you skip breakfast, activates your sympathetic nervous system: the system responsible for the fight-or-flight response.

One of the most effective ways to bring cortisol back into balance is simply stepping outside into a natural space. Exposure to green spaces activates the parasympathetic nervous system, the counterpart to fight-or-flight, which helps your body rest, recover, and regulate. When cortisol is balanced, you benefit in several important ways: your heart rate lowers, your blood pressure improves, and your cells become more sensitive to insulin, meaning your body metabolizes food more efficiently and blood glucose stays more stable (2).

Your Immune System and the Microbiota of Nature

When you spend time in natural settings, your body is exposed to a wide and diverse range of microbiota, the microorganisms present in soil, plants, and the air around you. Far from being something to fear, this exposure can help train your immune system. A well-trained immune system is one that responds appropriately, rather than becoming overactivated. Green spaces help calibrate that response so your body can defend you effectively without tipping into chronic inflammation (3).

Reduced Inflammation

Inflammation is reduced through multiple pathways when you spend time in nature. First, when cortisol is balanced and your immune system is not overactivated, inflammatory signaling decreases. But there is also a more direct effect: natural environments expose you to less of what drives chronic inflammation in daily life — pollution, noise, and the kind of ambient stress that urban environments generate almost constantly. Going outside gives your body a genuine break from those inputs.

Attention Restoration

Finally, there is a neurological benefit worth naming. Research shows that exposure to natural spaces improves attention restoration, meaning your ability to focus returns more easily after time spent outdoors. The natural environment engages the brain in a gentle, effortless way that allows the parts responsible for directed attention to recover. This is why so many people find that a walk outside clears their head far better than taking a break indoors (4).

This is exactly why nature helped me while I was a medical student and a college student both. Being able to spend some time outdoors resets your brain and allows you to pay more attention when you go back to trying to give your focus to whatever you're studying.

Nature designed our bodies to thrive in relationship with the natural world. Sunshine and green spaces are not luxuries. They are tools your body already knows how to use. Now let's look at where those tools make the most difference.

How nature supports stress relief, sleep, immunity, and overall health.

Three Key Areas of Health That Improve with Nature Exposure

Let's explore three categories where nature therapy makes a powerful difference: mental health, cardiovascular health, and immunity.

Mental Health: Anxiety, Depression, and ADHD

It is hard to imagine an environment free of anxiety. As we all know, anxiety is common and can be detrimental to a person. The DSM-5 describes it as excessive fear or worry, disproportionate to the actual threat, lasting at least six months, and accompanied by physical symptoms like restlessness, fatigue, difficulty concentrating, and sleep disturbance (5). Anxiety, fears, and worries are real sufferings that a person can have. But there is hope.

Think of your health as a toolbox. Maybe you already have some tools in there, like sleep hygiene, healthy eating, psychological support, or medication when needed. What we want to do today is add one more, if you don't have it yet. That tool is simply going outside and getting some sunshine.

When we are exposed to broad spectrum light, it activates brain pathways, modulating the prefrontal cortex activity and amygdala, with effects on emotional (fear and stress) processing occurring through retina-brain circuits involving the thalamus, hypothalamus, and other subcortical structures (6). There are also additional mechanisms researchers are still uncovering. What most research suggests, though, is that exposure to light and green spaces helps decrease anxiety through both known and unknown pathways (7).

Depression follows a similar story. The DSM-5 describes it as depressed mood, decreased pleasure, and changes in appetite, among other symptoms, lasting at least two weeks (8). What causes it is multifactorial: an unexpected loss, a difficult financial situation, sleep deprivation, rejection, low self-esteem, prolonged stress, or unresolved pain from the past. Between 2013 and 2023, the prevalence of depressive symptoms in adults rose from around 8% to over 12% (9). Today more than ever, we need to rethink how we can help ourselves and the generations to come. Lifestyle plays a crucial role in improving our mental health.

Regardless of the cause, green spaces can help to a notable degree. Depression can range in severity, and it can be managed with tools like psychological therapy, social support, medication when needed, and nutrition. But nature exposure should not be excluded. It helps reset your circadian rhythm, which is incredibly powerful.

When your circadian rhythm is balanced, serotonin gets regulated. Cortisol decreases. Vitamin D increases. A sense of calm begins to grow. Optimism starts to flourish. And the person feels much better.

What about ADHD? It follows a similar pattern. Disruptions in the circadian rhythm can affect the brain's ability to regulate attention and impulse control, two of the core challenges in ADHD. Early morning sunshine helps bring that rhythm back into alignment. Dimming your lights at night and turning off blue and white light from screens allows melatonin to do its job as evening comes.

Cardiovascular Health: Protecting Your Heart

Heart disease continues to be the number one cause of death worldwide. While death is a natural part of life, premature suffering from preventable heart disease does not have to be.

Heart disease has many contributing factors: high saturated fat intake, poor sleep, chronic stress, and anxiety, among others. Alongside eating well and improving sleep, another powerful tool is exposing yourself to green spaces and sunlight, preferably in the morning.

When UVA rays touch your skin at any time of day, nitric oxide stored in your skin enters your bloodstream, and something remarkable happens. Your blood vessels dilate, meaning they widen. As a result, blood pressure decreases and heart function improves (10, 11).

Pause and reflect for a moment. How does it feel to know that simply getting some sunshine can help increase your longevity and quality of life?

So let's give it a try. Go outside for a nature walk. Expose yourself to the sun. Nitric oxide can be released, which can lower blood pressure. Cortisol may balance, and the sense of calmness increases. And if you do it in the morning, you'll sleep better at night. All of this contributes to a healthier heart.

Immunity: Strengthening Your Body's Defenses

Here is something worth sitting with. Our immune system helps fight germs and keeps cancer cells under control.

Green spaces and trees release natural compounds called phytoncides. Some studies suggest these airborne compounds may increase natural killer cell activity, particularly activating the cells that target viruses and tumor cells (12).

Soil exposure is another pathway worth knowing about. Some data suggest that it strengthens immune cells. T cells, responsible for building immunity against viruses and activating other immune cells, also improve with regular nature exposure. Though human scientific data is still limited, soil exposure as a pathway for strengthening immunity is a promising field worth watching (13).

Let's Go Outside

Stepping into nature can be the first step toward calm, clarity, and healing.

So which area of your life would you like to improve? Maybe you want to feel calm, or not anxious, or to take care of your heart health, or maybe more than one. Once you identify what is keeping you from having a quality life, let's create an actionable plan.

First, choose one thing that you think will work. Maybe an evening walk in your yard, or going to the beach to see the sunset, hear the waves, feel the wind. Once you choose the place, be sure that you are connected with the environment you chose, taking care of yourself and making sure that technology and virtual messages don't get in the way of relaxing and enjoying what is present.

Once you finish your activity, write down at least three things you found good as you enjoyed your own space in nature. It can be "I heard birds singing," or "kids playing and laughing," or "the breeze was fresh." It's your time, your experience. You are building a mind and a system that will make your life enjoyable. Keep your tools in a safe toolbox, so that once you need them, you know where they are.

And later, when you're in a stressful situation and can't get outside, take a moment to breathe deeply and visualize those beautiful moments in nature. That mental break is more powerful than it sounds. See our blog on Serenity for more.

What's one way you can bring more nature into your week? I'd love to hear from you.

We offer a free Discovery Call, where we can talk about your goals, your limitations and how you could manage your time to be able to expose yourself to sunlight and take advantage of the benefits of it, in a realistic way in your life, right now. With the experience of Dr. Gio or Dr. Chelsea, we can help you create a plan that feels supportive and not overwhelming.

Giomarell Feliciano, M.D., MPH, NBC-HWC Medical doctor and board-certified health coach who helps busy professionals reclaim their wellness through plant-based nutrition, emotional resilience, and sustainable lifestyle changes. Learn More

References

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