Light is considered hope, life and essential. In the summer, when the sky is blue, our bodies are surrounded by clouds of illumination up to 100,000 Lux. It’s a completely different story in the winter, when the luminosity only reaches about 3,500 lux, far too dim for many people. Not a few suffer from winter depression, according to a study by the opinion research institute Forsa and Techniker Krankenkasse, even a third of all Germans. Little light and gray sadness – all this changes abruptly with the bright white snow and the dazzling light it reflects.
Snow is actually colorless
By the way: Snow is actually colorless, the incident light is only so often refracted by its complicated structure that the snow suddenly appears white. After all, this white is our happiness. After all, what looks brighter in winter than a closed blanket of snow? How happy we are in the white winter landscape – fortunately also with the sun. For what reason? According to the researchers, the key lies in the levels of serotonin and melatonin. When it gets dark earlier in winter, the level of the “sleep hormone” melatonin rises during the day. The result: we feel tired and listless. Brightness shifts sleep hormone. In the snow-white winter, we suddenly become much more alert and alert.
30 percent less serotonin on dark days
But bright white light at all wavelengths is in short supply in our latitudes in autumn and winter. Lack of light has a direct effect on the formation of serotonin, as Kasper and his team have shown in a study. Consequently, the intensity of the sun affects the strength with which serotonin 1A receptors on nerve cells bind the messenger substance. After dark days, the serotonin binding in the participants decreased by up to 30%. This was often accompanied by a depressed mood and listlessness. Conversely, brightness and exposure to sunlight increase serotonin levels.
Despite the snow: there is not enough light for the formation of vitamin D
But despite all the delight in the white snow and the brightness – despite the sun and the snow, the light in winter in Germany is not sufficient for the formation of vitamin D. According to the Robert Koch Institute, UV-B radiation with a length wavelength from 290 nm to 315 nm is required for low endogenous vitamin D formation, which occurs year-round only in regions below the 35th parallel. In Germany, which lies between the 47th and 55th degree latitude, body formation is only possible from about March to October when staying outdoors. During this period, the body can, in addition to meeting acute needs, also build up reserves of vitamin D in adipose and muscle tissue, which it can fall back on in the winter months.
However, any light helps for serotonin and to suppress the sleep hormone melatonin. So when the snow covers the fields in the dark winter and is even reflected by the sun, this is a celebration of brightness. Then come the well-known sensations of happiness in the snow, which make us feel like children again, inspire and soothe us infinitely.
