The Top 5 Health Benefits of Sunlight Exposure

While it’s well-established that one of the leading benefits of sunlight exposure is its ability to boost vitamin D production in the skin, the advantages of sunshine go far beyond that. However, excessive time spent in the sun can also have negative consequences for the skin. Therefore, a healthy and moderate amount of sun exposure is ideal. This translates to approximately 15 minutes of mid-day sunlight for those with lighter skin pigmentation and about 30 minutes for darker-skinned individuals. 

In this article, learn more about the top five benefits of sunshine that go beyond vitamin D, ranging from heart health to happiness.

The Benefits of Sunlight Exposure 

1. Improves Mood

Most people know intuitively that being out in the sunshine makes them feel good — beyond that, there is plenty of research to back up this feel-good benefit of sunlight.

Exposure to sunlight is thought to boost serotonin levels, which is a neurotransmitter that provides feelings of calmness and improved mood. This is exhibited by the prevalence of people with the condition of Seasonal Affective Disorder, which is a mood disorder with depressive symptoms that upticks during the sunless winter months and is alleviated by light therapy. 

In a randomized controlled trial published in Heliyon in July 2020, post-stroke patients exposed to 30 minutes or more of sunlight per day for 14 days experienced significant reductions in depressive symptoms compared to those without sun exposure. As depression is a common post-stroke symptom, spending time in sunlight may be a simple way to improve outcomes after a stroke.

Getting adequate sunshine can also improve mood for office employees. Published in May 2016 in PLoS One, workers exposed to sunlight during the workday had reduced levels of depression and improved job satisfaction. Even if your office doesn’t provide natural daylight, going outside for 10 minutes twice per day can improve mood.

2. Regulates Circadian Rhythm 

The timing of our sleep-wake cycles is governed by the circadian rhythm, which is the body’s 24-hour internal clock. Circadian rhythm is controlled by light exposure, as various wavelengths of light alter melatonin production. A tiny region of the brain, the suprachiasmatic nuclei (SCN), is responsible for keeping the circadian rhythm’s pace. 

Specifically, exposing the eyes to direct sunlight in the morning hours is linked to improved sleep that night. Typically, melatonin is only produced after sundown and is halted during the day. 

When exposed to the blue light wavelength from the morning sun, your eyes send a signal to the SCN in the hypothalamus to wake up — essentially, starting your day. Although melatonin production is paused at this time, it leads to your body producing melatonin earlier that evening, also known as melatonin rhythm phase advancement. This leads to a more effortless time falling asleep that night. 

Through the same mechanism, nighttime use of electronic devices can delay sleep, as the blue light emitted from them tricks your brain into believing it’s morning time again.

A disrupted circadian rhythm, often seen in cases of insomnia, jet lag, and night-shift workers, does more than just interrupt a good night’s sleep. It can also increase the risk of obesity, cardiovascular disease, metabolic syndrome, and impaired mental acuity. 

In summary, sun exposure — especially in the hours before noon, without sunglasses — can help regulate the circadian rhythm and improve sleep quality that night.

3. Improves Cardiovascular Health

The circadian rhythm also controls many aspects of cardiovascular function. For example, heart rate and blood pressure decrease during sleep and rise just before waking up. 

Research has found seasonal variations in cardiovascular risk factors. Cardiovascular-related mortality is significantly higher during winter than summer months, irrespective of age, location, or pre-existing conditions.  

Although the benefit of sunlight on cardiovascular health is due, in part, to an increase in vitamin D levels, researchers have looked at other mechanisms that may be at play. 

As described in an October 2016 paper published in the International Journal of Environmental Research and Public Health, exposure to ultraviolet radiation (UVR) stimulates nitric oxide production into the bloodstream. Nitric oxide acts as a vasodilator and is known to reduce blood pressure. 

Also, UVR exposure promotes several immune cells’ anti-inflammatory actions, including regulatory and helper T-cells. As high blood pressure and inflammation are leading risk factors for cardiovascular disease, reducing them is beneficial for heart health. 

A study published in Diabetes in November 2014 also found that sunlight provides more benefits than vitamin D supplementation on its own. In this research, obese mice were exposed to UVR or received supplemental vitamin D. The mice with UVR exposure experienced significantly improved glucose tolerance, lower cholesterol levels, and suppressed weight gain. In contrast, vitamin D-supplemented mice did not see the same benefits. 

High blood sugar, excess body fat around the waist, and abnormal cholesterol levels are three of the biomarkers associated with metabolic syndrome and high blood pressure. Metabolic syndrome significantly increases the risk of cardiovascular disease; therefore, moderate sunlight exposure may be a simple way to prevent this. 

4. May Reduce the Risk of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease in which the body attacks the central nervous system, causing neurological symptoms by damaging the protective myelin sheaths of nerve fibers. 

Although there are many potential causes of MS, it’s thought that inadequate sun exposure increases the risk of developing this disease. This theory came from research that observed an increased prevalence of MS in geographical locations farther from the equator, where UVR is weaker.

The role of sun exposure on the risk of MS was researched in a March 2018 paper published in Nutrients. The aptly named MS Sunshine Study found that higher lifetime sun exposure significantly reduced the risk of developing MS. In addition, this protective link was not explained by vitamin D levels — meaning, sunlight provides additional benefits beyond solely boosting vitamin D. 

Another study, published in Neurology in April 2018, found similar results. In this case-control study, women living in areas of high UVB exposure with self-reported higher sun exposure during childhood and early adulthood had a 45% lower risk of developing MS.

Although the mechanisms behind this protective benefit are not entirely clear, these studies indicate that adequate sun exposure may help prevent MS development.

5. May Improve Cognition and Brain Health

Moderate sunlight exposure may also benefit cognition and neurodegenerative diseases, including dementia and Parkinson’s disease (PD). 

A meta-analysis published in January 2019 in Medical Science Monitor pooled the results from three case-control studies of individuals with PD. The data showed that as little as 15 minutes of sunlight exposure per week was significantly linked to a reduced PD risk. 

Similarly, a study of over 16,000 adults, published in July 2009 in Environmental Health, found that low sunlight exposure was significantly linked to reduced cognitive function, especially in depressed individuals. 

A potential mechanism behind sunlight exposure improving cognition is hypothesized in a November 2012 paper published in PLoS One. The researchers found substantial seasonal variations in the production of BDNF (brain-derived neurotrophic factor), with the highest concentrations in spring and summer. BDNF is a crucial protein for memory, neural survival, cognition, and communication between neurons. Low levels of BDNF are often implicated in neurodegenerative diseases. 

Therefore, this seasonal increase in BDNF levels may be the link between sunlight exposure and improved brain health. 

Key Takeaways

• The benefits of sunlight exposure include improved mood, better sleep, and reductions in cardiovascular risk factors, with as little as 15 to 30 minutes per day of moderate sunshine. 
• Sun exposure may also reduce the risk of developing multiple sclerosis and improve cognition and neurodegenerative diseases. 
• Although sunlight is well-known for its ability to boost vitamin D, these health benefits are seen irrespective of serum vitamin D levels. 

References:

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