Dark spots result from faulty production of melanin, the tanning pigment. They often appear on the face, chest and hands. Dermatologists are unanimous on the matter: in the summer, dark spots reappear for 80% of us. Dark spots tend to appear after the age of 20; after this time, 20% of us are affected. This phenomenon is even more common when we reach 50. After this age, 90% of women are affected by dark spots. So, what is to blame? The sun and UV rays of course, but also blue light from the solar spectrum. This attacks the skin even when the sun is hidden behind the clouds. We must add that some dark spots are caused by hormones: the famous pregnancy mask. So, when you are pregnant, do not expose your skin to the sun.