Studies have already some shed light on this topic. Sadly, it is true - consulting the screens before going to bed is not the best idea. It alters the proper functioning of the nervous system and metabolism, disrupts the production of the sleep hormone, and even reduces our life expectancy... A new preliminary study, published in the journal Sleep in March 2020, added another disadvantage to this already long list: exposure to smartphones at night seems to have a negative effect on sperm quality.A significant correlationTo reach this conclusion, researchers at the Institute of Sleep and Fatigue at the Assuta Medical Center in Tel Aviv (Israel) analysed samples from 116 men aged between 21 and 59 years old. Performing an assessment of their fertility, the participants completed questionnaires on their sleep habits. The research team found that those who reported using their phones at night produced sperm that were less mobile and in smaller quantities.Amit Green, lead author of the study was quoted by the Telegraph as saying:To our knowledge, this is the first study to report these types of correlations between sperm quality and time of exposure to short-wavelength light (blue light) emitted by digital media, particularly smartphones and tablets, in the evening and after bedtime.Men who slept longer also had more sperm that were in better shape, as opposed to men who spent less time in bed who had poorer quality sperm. Blue Light - a problem but not the only oneWhile the blue light emitted by computers, smartphones and other tablets is often blamed, it may not be the only culprit. Electromagnetic radiation emitted by the devices could also be one of the factors associated with these changes in the quality of this biological liquid. The radiation emitted would, in fact, cause the heating of the organic tissues and therefore of the temperature of the sperm, thus interfering with its production.Because "to produce sperm of the highest quality, [the testicles] must be kept cooler than the rest of the body," says the website of the US National Health Service. This is why they are on the outside of the body and not on the inside. Wearing tight underwear can increase their temperature by up to 1°C.Previous research had also looked at a potential link between telephone use and sperm quality. A 2008 study by the Cleveland Clinic Foundation (USA), for example, showed that sperm quality tended to decrease as the daily hours spent on the phone increased. Men who reported using their mobile phone more than four hours a day had on average lower viable sperm counts.But other surveys also point to poor diet, exposure to artificial hormones or smoking. To preserve fertility, sleep or more generally, your health, scientists advise that you should move your electronic devices away from your bed at least an hour before going to bed or even switch them off completely during the night.