Since the very beginning of our planet's existence, its environment has been shaped by the regular changing of days and nights, periods of light and periods of darkness. All living organisms, including humans, evolved in this environment and adapted to the natural cycle over many millions of years. Until the end of the 19th century, the only sources of light during the night were fire, the moon, and the stars. With the invention and proliferation of artificial lighting, however, people began to change the night environment in unprecedented ways, outside and inside their homes. Discussing this with lighting expert Hynek Medřický, we reflect on the possible consequences of this change and whether we can actually grasp all of them.