Vitamin D, Sunlight and Sensible Sunbathing (April to September)


‘Natural light is a vital element like water and air, as such, it should accompany the individual for as many hours of the day as the season permits.’  Dr Fritz Hollwich

The human species has co-evolved alongside sunlight. The suns light/dark cycles naturally regulates hormonal and biochemical bodily processes. The body requires regular intervals of sun contact (april to September in the UK) before winter, to stock up on vitamin D, which will be relied upon during the UV deprived winter months (September to April). The right dosage of sunlight is medicinal and essential for optimal health or disease preventing.

‘Attuning yourself to natural cycles fulfils inherited physiological and psychological requirements.’  Dr R Hobday

It is UV light that causes skin tanning and in excess burning. A tan is the skins natural self-defence mechanism that prevents itself from any further UV injury. ‘Chronic over exposure’ to UV light for several hours over several years is what causes permanent structural skin changes (premature aging, wrinkles/lines and skin cancer). Sunburn increases ‘free radicals’ in the skin that can oxidise (damage) localised tissues. Excess ‘un-neutralised’ free radicals in the body will lead to inflammation and inflammatory-related diseases. However lack of solar radiation exposure is more of a prevalent problem than too much, ‘vitamin D deficiency’ is an unrecognised epidemic – the most common deficiency worldwide.

Modern day sunbeds are design to give you a ‘fast tan’ all-year-round. They emit a higher proportion of UVA than sunlight, which is highly penetrative and increases photo-aging (it’s not safer than UVB in sunlight). light bulbs have a limited spectral distribution compared to sunlight,  largely composing of yellow, red and infra-red light.

Vitamin D

UV light activates vitamin D production in our skin. Vitamin D is an essential nutrient required by the body. It enables numerous vital functions like our skeletal structures, our blood pressure, immunity, mood and brain function etc. It’s really a pro-hormone (a chemical signaller that controls/regulates bodily functions). Being Fat soluble it can be stored in body fat, the liver as well as skeletal muscle and drawn upon in periods of low UV.  Excess Vitamin D produced by sun bathing is automatically destroyed therefore toxic levels can never be reached and sunlight produced vitamin D last 2-3 x longer in the body than dietary/supplemental obtained vitamin D. Blocking/avoiding UV skin exposure stops vitamin D production, increases blood-cholesterol levels, reduces calcium absorption, increases calcium bone leeching, decreases serotonin production and increases melatonin.

If you get the right amount of sun at the right times of the year there’s no need to supplement vitamin D (like our ancestors). It is impossible to meet our daily recommended dose of vitamin D through diet alone.

Sunlight Benefits:

  • Natural antibacterial – increasing wound recovery, reducing infectious disease susceptibility and improves household hygiene (a well Sunlit, ventilated building reduces bacteria and dust aka bacterial food)
  • The blue spectrum of visible light eliminates bodily toxins by breaking them down at the skins surface
  • There is a good correlation between sunlight exposure and low incidence of internal cancers
  • Sunlight and fresh air has been shown to reduce muscular atrophy (wasting) even when immobilized
  • Sunlight that enters the eyes increases serotonin production which controls mood, sleep, body temperature, digestion, sex drive and supresses’ neurohormone melatonin. A lack of serotonin or excess melatonin causes sleepiness, decreases brain activity and slows all physiological processes (metabolism). Serotonin naturally decreases during winter
  • 10 mins of full spectrum sun light 2-3 x weeks has been shown to decrease SAD symptoms.

UV light Benefits:

  • Increases white blood cells (lymphocytes) that defend against infections.
  • Increases oxygen content of blood
  • Decreases blood-sugar levels in normal and diabetic cases. Vitamin D may contribute to maintaining insulin secretion. Vitamin D supplementation can increase insulin sensitivity and decrease inflammation.
  • Sunlight rapidly decreases cholesterol levels, UVB breaks down circulating blood-cholesterol at the skins surface
  • Can decrease blood pressure – systolic by 40mmHg and diastolic by 20mmHg. There are natural geographic and seasonal relationships associated with blood pressure (increasing further form the equator and in winter periods)
  • Increases a hearts ‘stroke volume’ (the amount it can pump with each contraction) by up to 39% similar to the effect of exercise.

Influencers of ground level UV strength:

  • The elevation of the sun relative to the horizon, this sets the length of the sun’s rays travelling through the earth’s atmosphere. The longer the path the more UV absorbed. Maximal UV strength occurs mid-day, at the shortest path!
  • Closeness to equator (latitude). The sunlight at the equator has ½ as much atmosphere to pass through than Polar Regions, UV light is 4 times stronger.
  • Height above sea level (altitude). Every 1 mile above sea level equals a 10% increase in UV.
  • The amount of dust, haze, water vapour and cloud cover in the atmosphere will affect UV strength more than visible light. Therefore ground level brightness cannot be a reliable indicator of UV intensity.
  • Clouds filter more infra-red than UV which means that sunlight heat is diminished while UV rays still get through. Heavy cloud can decrease UV by 30% and storm clouds by 100%.
  • Sunlight passing though glass filters out UV light and stops vitamin D production.
  • There are devises that can be brought to directly measure UV levels but on a more practical basis just pay attention to your own individual skin reaction.

‘Wearing protective clothing year round is the strongest indicator of a vitamin D deficiency.’  Dr R Hobday

Sensible Sunbathing:

There is a casual link between UV radiation (sun ‘burning’) and malignant melanoma. The ‘way’ we sunbathe is the most crucial factor. Remember there are more health related problems induced by low/no sun exposure and low vitamin D levels. People who spend long periods indoors and periodically subject themselves to intense bursts of strong sunlight are at greatest risk! Fair skinned people, with a tendency to freckle or have moles are at higher susceptibility to skin cancer. There’s no evidence that sunscreen can stop skin cancer. Immuno-suppressant drugs increase our susceptibility.

Skin Type and Sun exposure guidelines:

TypeGenetic ancestry

Sun Exposure guidelines


Celtic – Red hair with blue or green eyes and dark hair with green eyesUnused to direct sunlight will burn after 20mins of midsummer British sunshine


Northern European – Blond or red hair with blue or hazel eyes (pale skin & freckles)Unused to direct sunlight will burn after 30mins of midsummer British sunshine.


Northern European – Blond or brunette (fair skinned)Unused to direct sunlight will burn after 30 mins of midsummer British sunshine


Chinese, Japanese & Mediterranean – Dark hair and eyes (skin ranges from olive to brownUnused to direct sunlight will burn after 50 mins of midsummer British sunshine.


India, South America, Arabia – Dark hair and brown or black eyes (dark skinnedUnused to direct sunlight will burn after 70 mins of midsummer British sunshine.


Afro-Caribbean – Brown to black skinnedCan spend long periods in the sun with little risk of burning

The amount of melanin you have in your skin affects the rate of vitamin D you can produce; the fairer your skin, the more easily you can make Vitamin D but the less tolerable you are to sunlight exposure.

If you sit in the sun unexposed, without sunscreen for roughly 10 minutes, you are likely absorbing about 10,000 units of natural Vitamin D however keep in mind this amount differs from person to person depending on their skin tone.

Sensible Sunbathing Practical Guidelines:

  • Eat a wholefoods diet with plenty of fresh fruits and vegetable to increase free radical neutralising antioxidants. Avoid processed foods which are micronutrient-robbing foods.
  • Northern latitudes (32° north +) like the UK capture the right UVB wavelengths to produce vitamin D at ground level for 7 months of the year (from early April till late September)
  • Sunrise and sunset radiation is mainly UVA. Morning Sun is the most beneficial between 9am and 3pm, face east with no sunglasses or contact lenses (never look at the sun directly).
  • Avoid strong mid-day sun (when the shadow you cast is shorter than your own height) If you have to be out in strong sun for long periods use a physical filtering sunscreen with a strong SPF and wear protective clothing like a hat.
  • Sunbathe at temperatures of around 18°C (64°F) and below. Avoid temperatures of 25°C (77°F) and above.
  • Never sunbath in a breeze, you’ll get the illusion of coolness which can lead to sun burn.
  • Never burn, avoid skin reddening, the timing of which is individually determined. If you do get sun burnt aloe vera is one of the best remedies to help repair your skin.
  • If you are sensitive to sunlight begin with just your feet, then legs and arms before exposing the abdomen and chest. Progress at your own rate
  • 3-4 small sunlight exposures are better than one single prolonged exposure.
  • Start with 5 minute exposure and gradually progress to 20 minutes people with the darkest skin may need to do this 3x day.
  • Exposing your skin in spring and early summer will build up your tolerance for stronger sun in the summer.
  • Vitamin D does not immediately enter your bloodstream. It may take up to 48 hours. Showering immediately after sun exposure may wash away the vitamin D and potentially reduce the benefits of sun exposure.

 ‘Worldwide the countries where chemical sunscreens have been recommended and adopted have experienced the greatest rise in Malignant Melanoma (a type of skin cancer).’ Dr F & C Garland