Melanin is essentially the pigment in our skin that gives it colour (the absence of melanin in human is responsible for albinism), but sometimes, it can backfire and cause pigmentation in the form of dark patches or spots that usually surface in mature skin.
Skin is made up of the epidermis, which is divided into four layers, starting with the outermost layer: stratum corneum (SC), stratum granulosum (SG), stratum spinosum (SS), and stratum basale (SB).
Melanin is produced when amino acid tyrosine oxidises in the melanocyte cells located at the stratum basale layer. Skin produces melanin to protect skin cells and scatter UV rays, the same reason why you get a tan when you’re out in the sun for too long. Over time, often after many years, these melanocytes may multiply, causing an uneven concentration of active melanocytes in the skin which eventually results in dark patches or spots.
Often enough, this damage or uneven distribution of melanocytes goes unnoticed until it is too late. Most spots and pigmentation are formed earlier in life and is aggravated further if you are exposed to the sun often without wearing sunscreen.
Preventing the appearance of pigmentation when you’re older is a hard and long battle – there won’t be instant gratification when you put on sunscreen, it is the surest way of ensuring that dark spots are kept to a minimum.