Heliotherapy: The Therapeutic Use of Sunlight

“O, Sunlight! The most precious gold to be found on Earth.” -Roman Payne

Ladies and Gentleman, rejoice! For now, it is the season of the sun! Now is the prime time to shake off winter, get outside, soak up the sun, and start producing a year's worth of vital vitamin D. The days are getting longer, the plants are getting greener, and the sun is getting warmer. Sunbathing season has officially begun!
With the warmer weather and the hotter sun, sunburns are beginning to appear on the fair-skinned folk everywhere. Most people love the feel of the warm sun on their skin, but feeling the heat of sunburn on the skin hours after the sun has set is definitely not desirable. So, do you want to know how to gain full benefits from the sun in a safe manner?


Let’s clear this difference up first thing. Sunbathing is NOT the same as heliotherapy. There are overlaps, for sure, but they are not inherently the same.

Sunbathing (noun)

The activity of sitting or lying in the sun with the intent of warming and tanning the skin.

vs Heliotherapy (noun)

The therapeutic use of sunlight for health.



Sunbathing is an activity of leisure and of pleasure. For some it is almost a form of worship. The primary purpose of sunbathing is to warm the skin, get a tan, and produce vitamin D while enjoying the great outdoors. Sunbathing involves being in the sun for an extended period of time. Most sunbathers seek out sunny locations such as a beach, pool, or open patio preferably with a slight breeze and cool drink. Because it usually involves being in direct sunlight for an extended period of time, mindfulness should be employed and precautions should be taken in order to prevent adverse effects. One way to gage the length of sunbathing before burning is to consult the UV Index for your sunbathing location. This can be found online or on an app on your phone. The UV Index is a scale that tells you how much UV radiation is reaching the surface of the earth, and subsequently absorbing into your skin. UV rays are different from red rays, which heat the skin. So, it can be quite cold or even slightly overcast and still have a high UV Index. This is why snowboarders and skiers can get sunburnt!

Sunbathing Checklist and requirements:

  • Sunshine
  • Warm weather
  • UV Index level of 3+
  • Open space
  • Lawn chair, towel, or blanket
  • Time
  • Minimal Clothing
  • Cool beverage
  • Sunscreen (SPF 15+)
  • Aloe vera
  • Hat
  • Sunglasses

Some other sunbathing factors to consider:

  • Sunbathing drains your energy and leads to lethargy. The reasons for this are at least three-fold:
    • Your body is trying to control it’s temperature
    • You’re Dehydrated.
    • Your body is Experiencing chemical changes (vitamin D and serotonin production, pigmentation changes, dehydration)
  • Sunbathing can cause damage to your skin including burns, rashes, blisters, photoaging, actinic keratoses (pre-cancer patches), melanoma, and carcinomas.
  • Sunbathing can lead Heat Exhaustion and then to Sunstroke (heat stroke).
  • Not all sunscreens are made equally, nor do they all work the same.
    • Use a broad spectrum (UVA and UVB protection) sunscreen.
    • Mineral Sunscreens using zinc oxide and titanium oxide are better for you than chemical sunscreens.
      • Mineral sunscreen sits on top of the skin and reflect the suns rays. They are widely regarded as safe.
      • Chemical sunscreens absorb and penetrate into your skin converting the rays into heat to be dispelled through the skin. Chemical sunscreens contain active ingredients of avodbenzone, oxtinoxate, and oxybenzone. Oxybenzone and Octinoxate are both banned in Hawaii and Florida as they bleach and destroy the coral reefs. These ingredients have been suspected to cause hormone disruption and can be found in bodily fluids such as the blood and even breast milk.
    • Sunscreens expire and should be replaced every year. No exceptions. Expired sunscreen can actually cause more harm to the body than not wearing any at all. Ingredients can separate and magnify the effects of the sun rather than repel them. Heat and humidity also break down sunscreen and will accelerate their expiration date regardless of the date stamped on the bottle.


Heliotherapy is the act of using the sun’s UV rays to achieve a specific health or healing goal. The goal could be as simple as producing vitamin D to as extreme as healing Tuberculosis or certain cancers. (It should be noted that if one is trying to achieve healing of a serious medical condition, it would be prudent and wise to seek out a specialist trained in heliotherapy for that particular condition.) Heliotherapy is best achieved under specific conditions. That said, we can all practice a bit of Heliotherapy for the purpose of raising and maintaining optimal vitamin D levels.

Heliotherapy Checklist and Requirements:

  • Morning Sun. Morning sun (when UV Index is 3 – 5) is the gentlest sunshine. It also helps transition your body from producing melatonin (sleep hormone) to serotonin (happy and alert hormone). Far northern or southern latitudes may need to wait until noon to achieve this optimum UV Index range.
  • Cool weather no warmer than 64⁰F (18⁰C). This recommendation comes from Dr. August Rollier and other pioneering heliotherapists in the early 1900’s. A study done in 2014 showed evidence that cooler ambient air increases metabolism. Vitamin D must first be metabolized into its hormonal form before it can function within the body.
  • UV Index of 3 – 5. A UV Index score between 3 – 5 is considered a low - moderate risk and most people can be out in the sun under 45 minutes before sun damage occurs. (as always, it is important to know yourself when it comes to unprotected sun exposure.)
  • Shelter from moving air. It is advised not to sunbathe in a breeze because the cooling effect on the body can give the impression that the intensity of the sun is less than it actually is. Thus leading to longer sun exposure than is needed, necessary, or prudent.
  • Lawn chair, towel, or blanket. Even bodily exposure to the sun and protection from the ground makes therapeutic sunbathing more efficient.
  • 15 – 30-minute time increments. Limiting unprotected time in the sun is the key to safe sun exposure. It helps avoid overdosing on the sun.
  • Consistent Nourishing Meals. Well nourished skin is far more efficient at absorbing and processing the sun’s rays than dried out, malnourished, and atrophied skin. Make sure adequate amounts of essential fatty acids like Omega 3’s and 6’s, healthy fats, and beta carotene are being consumed.
    • Skin healthy foods include: Salmon, Avocados, Walnuts, Sunflower Seeds, Sweet Potatoes, Red and Yellow Bell Peppers, Broccoli, Tomatoes, Soy, Red Grapes, Green Tea, and DARK CHOCOLATE (70%+)!
  • Adequate Hydration. The skin is an organ and as such functions optimally when properly hydrated. This includes hydrating from the inside as well as the outside. Drinking appropriate amounts of water hydrates from within while applying a high-quality moisturizer hydrates from the outside. Good quality oils, butters and waxes can also hydrate the skin while providing a barrier that nourishes the skin while also keeping the skin hydrated.
  • 30%+ bare skin with face, neck, and groin covered. Obviously, some skin needs to be exposed in order to benefit from the sun’s rays. In the early 1900’s when heliotherapy was employed by physicians, sun was administered incrementally session by session. This was done by first exposing the feet, then the knees, then the who leg, then the lower torso, and finally the chest and arms working up from 5-minute increments to and hour at a time.


Heliotherapy provides all the therapeutic benefits of sunbathing while incorporating safe practices of limited unprotected sun exposure during the gentlest times of day. It allows for a very gradual and safely acquired tan rather than the dangerous practice of sun binging. If unprotected sun exposure is regarded in the same way as a vitamin or supplement and is taken at the recommended dosage only, the sun can be very healthy. It is only when too much is taken that dangerous side effects are produced. Again, it is vitally important to “know thyself” in order to determine the length (or dosage) of sunlight needed to produce the optimum amount of sunlight.


“Sunlight, is like good champagne. It invigorates and stimulates; indulged in to excess, it intoxicates and poisons.”

-Sir Henry Gauvain


Temperature is how warm the air is outside. Duh. We all know that. But have you ever noticed that 75 degrees at noon feels a lot different than 75 degrees in the evening? Well that is due to the UV Index.

The UV Index tells you how much UV (ultraviolet) rays are making it through the ozone layer and atmosphere and hitting the earth. There are two types of UV rays that make to the earth's surface: UVA and UVB.

UVA rays penetrate into the inner cells of the skin, including the dermal layer. They are the cause of immediate tanning and sunburn and cause premature aging, wrinkles, and some skin cancers. UVA rays account for approximately 95% of the rays that make it through the atmosphere. They can penetrate clouds and windows.

UVB rays affect the top layer of skin cells and are responsible for delayed tanning, sunburn, and blistering (read second-degree sunburn). These rays are responsible for most skin cancers as they directly damage dermal DNA. Only about 5% of UVB rays make it through the atmosphere to the earth's surface and are not able to penetrate windows.


The UV Index is quite easy to navigate if you have the chart in front of you. Most weather apps will tell you the UV index at any given moment. The index tells you how strong the sun’s ultraviolet rays are as they hit the earth’s surface. The level of the UV Index will tell you approximately how long it will take for a fair-skinned person to burn. It will also indicate how long you need to be in the sun “unprotected” in order to get your daily quota of vitamin D.

For example: In Oslo, Norway, the average UV Index number in June is 5. That means that it will take at least 45 minutes before a fair-skinned person, with no sunscreen, burns. Also, according to a study done, it takes about 30 minutes of midday summer sun (so approximately a UV Index of 5) in order to produce between 10,000 – 20,000 IU of vitamin D. Another study found that about 13 minutes of midday summer sun in the UK 3 times per week produced enough vitamin D to maintain healthy levels.

In order to produce vitamin D, the UV Index needs to be greater than 3, which occurs when the sun is optimally at least 45⁰ above the horizon. This is why optimal vitamin d Production occurs during the midday hours.

Factors to Consider for Sun Exposure

  1. Altitude. UV exposure increases about 4% for every 1000 ft gain in elevation because there is less atmosphere to block sunlight.
  2. Latitude. The further away from the equator you get, the longer the suns rays have to travel before they reach the earth’s surface. As such, high UV Index scores become less and less common the further away from the equator you get. This also means that more time in the sun is required in order to achieve optimum levels of vitamin D. IN the furthest areas, it may not be possible to achieve the daily recommended amount of vitamin D from the sun alone. Dietary supplementation is recommended in these cases.
  3. Season. This relates to the tilt of the earth on its axis. During the cold, dark months of winter, the sun has to travel through more atmosphere before hitting the earth’s surface as opposed to the hot, bright months of the summer when the sun’s rays have the shortest distance through the atmosphere to reach the earth’s surface. The longer the rays, the lower the UV Index, the longer it takes to produce vitamin D.
  4. Age. Children younger than 6 and adults older than 65 have a harder time synthesizing vitamin D naturally in their skin. These age groups also have a higher sensitivity to burning from unprotected sun exposure.
  5. Skin Color. Melanin is the pigment in our skin that determines how dark or light our skin is. The presence of melanin also acts as a natural sunscreen and is a determining factor in how quickly we sunburn. It is also a determining factor in how much sun exposure we need in order to produce optimum levels of vitamin D. Those with a lot of melanin in their skin are naturally very dark and therefore require a much longer exposure to sunlight than those with little melanin and are very fair skinned.
  6. Medications. Certain medications can cause photosensitivity and will expedite the amount of time in the sun before getting sunburnt. This does not also expedite the amount of time needed to synthesize vitamin D and dietary supplementation is often required.


This depends on several factors that include age, skin color, latitude, altitude, daily sun exposure, types of clothing commonly worn, diet, overall health, and prescription medications.

On average though, most people need only 400 – 800 IU or 10 – 20 mcg per day. However, some people who are deficient will need as high as 5000 IU per day. A simple blood test done by your general practitioner will tell you what your levels are, if you need oral supplements, or if sun exposure alone will fill your daily quota of vitamin D.


Image by ArtTower from Pixabay

It is estimated that approximately 42% of population in the United States do not have enough vitamin D in their lives. That percentage rises in various demographics of people such as: those who are serial sunscreen users or sun avoiders, people with very dark skin, people who are over the age of 65, and those who live beyond 37⁰ latitude.

Vitamin D insufficiency is a precursor to Vitamin D deficiency. The difference is how low the blood levels of vitamin D are. When the vitamin D blood level falls below 32 ng/mL, it is first diagnosed as an insufficiency. When that same vitamin D blood level falls below 20 ng/mL it becomes a deficiency.

Please note that if you believe that you have low vitamin D levels that cannot be rectified by diet or sun exposure, please check with your doctor prior to taking OTC vitamin D supplements. Your doctor will order a blood test that will determine your Vitamin D levels and will then recommend to you an appropriate dosage. Overdosing on vitamin D supplements can cause other problems like hypercalcemia, or a buildup of calcium in your blood which then causes vomiting, weakness, bone pain, kidney problems and the formation of calcium stones.  Vitamin D overdose cannot be achieved through diet and sun exposure alone.


So, what is so special about Vitamin D? Well, it turns out that vitamin D is a pretty crucial component to our overall immediate and long-term health. Vitamin D is actually a hormone, not a vitamin, that is naturally produced in the skin when exposed to sunlight and therefore has been quaintly dubbed “the sunshine vitamin.”

  1. Bone Health. Vitamin D is needed for calcium and phosphorus to be absorbed from the digestive system to be utilized by the body to remineralize and strengthen the skeletal system. No vitamin D = No strong bones.
  2. Energy. A study done in 2014 found that in 77.2% of people who presented with fatigue were deficient in vitamin D levels. When those vitamin D levels were raised to normal healthy levels, significant improvement in energy levels were reported and recorded.
  3. Weight loss. Vitamin D deficiency is common in overweight and obese people and studies have found a correlation between vitamin D3 supplementation and weight loss. Ironically, they also found that with the weight loss, natural production of vitamin D then increased. Possibly this is partly due to the decrease in fatigue that is found with healthy blood levels of vitamin D.
  4. Reduces depression. Researchers have found a correlation in many people who present with clinical depression and low vitamin D blood levels. This is particularly true in older adults. Some studies have gone on to show that vitamin D supplementation can reduce depressive symptoms particularly in those who experience Seasonal Affective Disorder (SAD).
  5. Improves immune function and Fights disease. Vitamin D supplementation has been found in numerous studies to improve the immune system and aid in healing severe disorders such as tuberculosis, psoriasis, multiple sclerosis, some cancers, chest infections, flesh wounds, cataracts, influenza, and respiratory infections.
  6. Blood health. Vitamin D deficiency has been linked in multiple studies with stiffer and less flexible blood vessels as well as increased instance of deep vein thrombosis (DVT) or blood clots. Further, vitamin D deficiency has also been recognized as a risk factor for heart attacks, congestive heart failure, peripheral arterial disease, strokes, and other conditions associated with cardiovascular disease.

 A final thought:


Recently, reports have started coming out across the globe of increased blood clotting in the people infected with COVID-19. These blood clots are

occurring in those hospitalized as well as those who are asymptomatic. And these blood clots are causing MAJOR problems such as: strokes, heart

attacks, and pulmonary embolisms, as well as preventing and complicating renal dialysis and other health conditions. Obviously, medical professionals and researchers are tackling this problem with the best of their knowledge and abilities. Northwestern University just put out a report dated May 7, 2020 stating that Vitamin D levels appear to play a role in COVID-19 mortality rates. Saying that “Patients with severe deficiency are twice as likely to experience major complications.” There is no current evidence that sufficient vitamin D levels will prevent infection, contagion, or death from this virus. However, there does seem to be emerging evidence that sufficient vitamin D levels will strengthen the innate immune system and decrease the overactive immune response (cytokine storm) that is common in those infected with COVID-19. Possibly, this partially could explain why young children are less likely to show symptoms of COVID-19. They are more likely to play outside and allow their body to naturally synthesize vitamin D. Linearly, it would make sense that if we all spent a little bit of time in the sun each day, socially distancing of course, we could produce our daily need of vitamin D and possibly weather this pandemic just a little better.

Three Phone Apps I Find Useful:






Artemis, Nadine. Renegade Beauty: Reveal and Revive Your Natural Radiance: Beauty Secrets, Solutions and Preparations. North Atlantic Books, 2017.

Cates, Trevor. Clean Skin from within: the Spa Doctors 2-Week Program to Glowing, Naturally Youthful Skin. Fair Winds, 2017.

Hobday, Richard. The Healing Sun: Sunshine and Health for the 21st Century. Findhorn, 1999.


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2 thoughts on “Heliotherapy: The Therapeutic Use of Sunlight

  1. This is a very informative, interesting, and useful article! Thanks so much for all your time spent researching this subject!

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