I really need a tan fast!
Melanin, the pigment in your skin triggered by the sun’s UV rays, appears only gradually, which is why a day of prolonged exposure in the sun results in a burn, not an attractive tan. Your melanin production can’t keep up with an intense burst of light, which is why lotions are necessary to slow the UV light getting through to skin, and why multiple, shorter sessions are ideal for getting a deep, long-lasting tan. When tanning under the sun, it can be difficult to predict when your skin is getting UV rays too quickly or too intensely; hours or days of tanning can be ruined if you’ve gone just one hour too long.
The principle of slow and consistent exposure is the same when using a tanning bed, except that the special tanning bulbs in beds are designed to speed up the process by delivering two hours of equivalent sunlight in about five minutes. With about five to seven days of regular tanning sessions, the skin can have enough regular, even exposure to produce a lasting tan that won’t leave the skin as dry or prone to peeling as natural methods.