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How do Sunless Tanning Products Work?Skin is made up of two main layers: the epidermis on the outside and the dermis on the inside. Whether you are talking about sun tanning or self-tanning, the epidermis is where the action occurs. The epidermis is also made up of layers. The deepest layer of the epidermis, called the stratum basale (basal layer), is affected during sun tanning. The stratum corneum (horny layer) is the outermost layer of the epidermis -- it is this layer that is affected by most sunless-tanning products.
There are several different kinds of sunless-tanning products available today. People have been able to pour on a tan since 1960, when Coppertone® came out with the first sunless-tanning product -- QT® or Quick Tanning Lotion. If you are old enough to remember this, then you are probably thinking of the incredibly orange hue this lotion produced. Since then, there have been several advancements made on the sunless-tanning front. These days, you can find tanning pills, sunless- or self-tanners and bronzers. You can smooth, swipe or spray on a light bronze glow or a deep, dark tan. Many of these products take 45 minutes to one hour to start taking effect, and once you factor in drying time, you could be looking at about three hours spent achieving that sun-free tan. The most effective products available are sunless- or self-tanning lotions that contain dihydroxyacetone (DHA) as the active ingredient (American Academy of Dermatology). DHA is a colourless sugar that interacts with the dead cells located in the stratum corneum of the epidermis. As the sugar interacts with the dead skin cells, a colour change occurs. This change usually lasts about five to seven days from the initial application. Every day, millions of dead skin cells are sloughed off or worn away from the surface of your skin. In fact, every 35 to 45 days, you have an entirely new epidermis. This is why tans from sunless- or self-tanning lotions will gradually fade -- as the dead cells are worn away, so is your tan. For this reason, most of these products suggest that you reapply the sunless- or self-tanner about every three days to maintain your "tan." Although gels, lotions or sprays that contain DHA are said to be the most reliable and useful, there are dozens of other types of products on the market. Tanning accelerators -- lotions or pills that usually contain the amino acid tyrosine -- claim that they stimulate and increase melanin formation, thereby accelerating the tanning process. At this time, there is no scientific data available to support these claims. Another sunless-tanning product is a tanning pill that contains canthaxanthin, which is most commonly used as a colour additive in certain foods. Although the FDA has approved the use of canthaxanthin in food, it does not approve its use as a tanning agent. When used as a colour additive, only very small amounts of canthaxanthin are necessary. As a tanning agent, however, much larger quantities are used. After canthaxanthin is consumed, it is deposited all over your body, including in your skin, which turns an orange-brown colour. These types of tanning pills have been linked to various side effects, including hepatitis and canthaxanthin retinopathy, a condition in which yellow deposits form in the retina of the eye. Another popular form of sunless tanning is the bronzer. These powders and moisturizers, once applied, create a tan that can easily be removed with soap and water. More like make-up, these products tint or stain your skin only until they are washed off. It's important to remember that most of these products, unless they contain an added sunscreen, will not protect you from the sun's UVA and UVB rays. Even products that do contain a sunscreen won't be of much help, since they lose their efficacy within hours of application. So, if you're planning to head outside to show off your new glow, be sure to apply some extra sunscreen. Another tip, a Sunless Tan will only last as long as the “coloured” skin remains on the body so the use of moisturizers slowing down the shedding process with prolong the tan. What is Sunburn?Over the course of several hours, exposed skin turns bright red and becomes extremely painful when touched. The skin will often feel very warm as well. When you get sunburnt, you're basically killing skin cells. The outer layer of skin on your body is called the epidermis. The outermost cells of the epidermis -- the cells you see and feel on your arm, for example -- are dead. But just below the dead cells is a layer of living cells. These living cells continuously produce new dead cells to replenish your skin. By sitting in the sun, you expose yourself to ultraviolet light. Ultraviolet light has the ability to kill cells. Ultraviolet light hits the layer of living cells in the epidermis and starts damaging and killing them. As your body senses the dead cells, two things happen: The ways to avoid sunburn (without having to stay inside) are to use a sunscreen, which blocks ultraviolet light, or pace yourself so you get a tan first. When you get a tan, your body essentially creates its own sunscreen using its own special pigment cells in the epidermis. How Sunburns and Sun Tans WorkWith a nice tan you can go out in the sun and nothing happens unless you have "fair skin". Unfortunately the fair skinned never get a tan, so they always get sunburned unless they are wearing a sunscreen. How tanning worksWhen you get a tan, what is actually happening is that your melanocytes are producing melanin pigment in reaction to ultraviolet light in sunlight. Ultraviolet light stimulates melanin production. The pigment has the effect of absorbing the UV radiation in sunlight, so it protects the cells from UV damage. Melanin production takes a fair amount of time - that is why most people cannot get a tan in one day. You have to expose yourself to UV for a short period of time to activate the melanocytes. They produce melanin over the course of hours. By repeating this process over 5 to 7 days pigment builds up in your cells to a level that is protective. In a variety of races melanin production is continuous, so the skin is always pigmented to some degree. In these races the incidence of skin cancer is much lower because cells are constantly protected from UV radiation by melanin. Melanocytes actually produce two different pigments: eumelanin (brown) and phaeomelanin (yellow and red). Red-heads happen to produce more phaeomelanin and less eumelanin, which is why they don't tan very well. In albinos, the chemical pathway that produces melanin cannot proceed because an enzyme called Tyrosinase is missing. Melanocyte-stimulating hormone (MSH) is produced by the pituitary gland. MSH flows through the bloodstream and reaches the melanocytes, encouraging them to produce more melanin. The pituitary gland is tied into the optic nerve, which means that it can sense light resulting in the production of MSH. In fact a side effect of all of this is that wearing sunglasses may make you more susceptible to sunburn! How sunburn worksIf you are Caucasian and you don't have a tan, then the cells in your skin are not protected from the sun's ultraviolet radiation. You are therefore an easy target for sunburn if you spend too much time in the sun. As anyone who has sunburn knows, sunburn leaves your skin red and extremely painful. In severe cases the skin forms blisters. When you get sunburn, your skin is actually damaged by UV radiation and your body is responding to the damage. When you get sunburnt, what you are really getting is cellular damage from ultraviolet radiation. The body responds to the damage with increased blood flow to the capillary bed of the dermis in order to bring in cells to repair the damage. The extra blood in the capillaries causes the redness - if you press on sunburned skin it will turn white and then return to red as the capillaries refill. Evidence is now showing that the massive increase in skin cancer is as a result of sun exposure some 20 – 30 years ago in the majority of cases. This demonstrates the huge important of treating the inviting sun with respect. Food for thought: Treat the sun with respect, always use sunscreen, NEVER use the sun as a means to achieve a regular tan as human nature suggest that most of us to expose the skin too much. For cosmetic tanning, especially a tan that is required at short notice use a sunless tanning product. How Sunlight worksSunlight arrives on earth in three forms: infrared (heat), visible light and
ultraviolet. Ultraviolet light is classified into three categories: 99% of the sun's UV radiation at sea level is UVA. It is the UVB that causes most of the problems related to sun exposure: things like aging, wrinkles, cancer and so on, although research is increasingly implicating UVA as well. One of the interesting things about UV radiation is that it is reflected by different surfaces. These reflections can amplify the effects of UV exposure. For example, snow reflects 90% of UV light. That is why you can get snow blindness and severe sunburns from skiing on a sunny day. Sand can reflect up to 20% of UVB that hits it, meaning that you can get extra UV exposure at the beach. On the other hand, certain things absorb almost all UV radiation partially or completely. Glass is one of these substances, which is why you cannot get sunburn in a greenhouse. Most sunscreens use chemicals that have the same UV-absorbing properties.
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