Allowing the skin to slowly become accustomed to UV radiation from sunlight by moderate indoor tanning creates a protective effect, says the Sunlight Research Forum (SRF). Studies repeatedly find that continuous sun exposure below the erythema threshold (when the skin begins to redden) is essential in helping the human body to build up its natural self-protection mechanism against UV-ray overexposure. Pigmentation and the formation of the so-called “light callous” – a thickening of the skin's uppermost layer, the stratum corneum – create an effective dermatological barrier against excessive radiation’s harmful effects. This naturally produced effect is comparable to the protection offered by sun cream. "Regular sun bathing over a period of three to four weeks allows the light callous to fully develop. The thickened stratum corneum is better able to absorb UVB light and to prevent it from penetrating the rest of the epidermis,” explains Ad Brand from SRF. He continues by explaining how solar radiation boosts the production of the pigment melanin. “This skin pigment provides another layer of protection from UV radiation below the stratum corneum. Melanin is the substance which produces tanned skin. The more melanin stored, then the darker the suntan,” he shares.
“Tanning outdoors or in a solarium therefore provides greater protection from the sun by activating the skin’s own protection against UV rays.” Brand recommends that “the three to four weeks running up to a beach holiday should be used to build up the light callous layer and increase melanin production.” He warns that “Sudden overexposure to UV radiation without preparation can cause sunburn and increases the risk of developing skin cancer.”
SRF is a not-for-profit organization based in The Netherlands. SRF’s aim is to help bring to the forefront the latest medical and scientific information on the effects of moderate UV exposure on man. It takes time, often decades, for new scientific ideas to be accepted and assimilated, first into the general body of scientific knowledge and finally into policy. SRF wants to reduce this time to a minimum so that the benefits of research can lead to a better understanding of UV effects on man and will become available to the public without any unnecessary delay. The organization hopes to provide policy makers with correct information on which to base national health policy and individuals with better information on which to base choices about their lifestyles.