LED technology, which is gradually replacing our old sodium bulbs, has the advantage of providing more power for sharply lower electricity consumption. So, urban communities do not hesitate to equip their public lighting with this type of light bulb and get a direct benefit on energy bills.But from outer space, the observation is not the same and for astronauts it is more alarming than positive. Indeed, by photographing large cities, they noticed a sharp increase in light intensity and the pollution it generates.Many scientists specialised in the field agree that the same assessment can be made about the situation on Earth as the way it is seen from space: the spread of LEDs increases light pollution too quickly. Astronomers say they can no longer observe the stars and the Milky Way when they are too close to LED sources. For the scientific community, the impact of this technology would be even more harmful on organisms.LEDs would disrupt the natural rhythm of nocturnal animals that use moonlight to find and hunt their prey, or some migratory bird species that find their way according to the stars. LEDs also have consequences for the reproduction or sleep cycles of certain species.And what about humans? Same observation: LED has harmful effects, especially on the sleep cycle. According to specialists, by changing this rhythm, it would lead to more fatigue, stress, premature aging...At the rate things are going, we can consider that 70% of the light sources will be LEDs within 3 years, and the specialists do not seem very optimistic about the consequences.