Researchers have estimated the duration of solar radiation exposure required in order to obtain the recommended doses of vitamin D. While in spring and summer 10 to 20 minutes in the sun are enough, in the winter months almost two hours would be needed, therefore for the vast majority of the population it is difficult to achieve the optimal values. Every year, studies on the benefits of sunbathing in moderate doses are interspersed with those that confirm the risks of doing it excessively.