Only getting sunlight on your skin through the filter of a window might not be the best idea for your health. The sun has a plethora of wavelengths that impact our bodies, but the two you most need to know about are UVA and UVB. UV stands for ultraviolet, and these sun rays have long been known to influence our physiology. UVB is the most valuable for human health, as it’s the only wavelength that triggers your body to produce vitamin D.
The problem is that UVA has a much longer wavelength than UVB, and it can penetrate through various materials more easily. UVA can move right through the ozone layer, clouds, pollution, and even glass without being filtered out very much. UVB can’t make its way through glass very effectively, and it’s critical to help balance out the potentially harmful aspects of UVA. It’s not that sunlight is inherently bad; it’s just the way that we interact with it that can be unhealthy.
We need both UVA and UVB, but unhealthy exposure to UVA is what predominantly increases the risk of skin cancer and photoaging of your skin. Getting plenty of natural light through windows during the day is a wonderful thing. Again, that light is being picked up by your optical receptors and sending information to your brain to optimize your circadian timing system. However, exposing yourself to long periods of sunlight directly on your skin through windows should probably be avoided just to be on the safe side.
Also, it’s valuable to note that during certain times of the year, depending on where you are in the world, UVB isn’t making its way to your body anyway. Generally, during the winter months, it’s going to be more challenging to get UVB for most or all of the day. But, again, it depends on where you live.
More: 50 Tricks to Sleep Better Tonight