Northwestern University scientists and physicians are raising concerns about two proposals currently under review by the Federal Communications Commission (FCC) that could dramatically increase artificial light at night - potentially disrupting sleep, circadian rhythms and seasonal biological cycles.
In one proposal, startup Reflect Orbital plans to use large, mirrored satellites to redirect sunlight to Earth at night. While the proposal aims to illuminate solar farms, it potentially could flood entire cities with light that reaches daylight-level intensity. The FCC's public comment period for this proposal (SAT-LOA-20250701-00129) closes Friday (March 6).
The second proposal, from SpaceX, seeks approval for an orbital data center system that could include up to one million satellites in orbit. The large number of satellites can scatter sunlight, increasing overall sky brightness. The public comment period for that proposal (SAT-LOA-20260108-00016) closes Monday (March 9).
Researchers from Northwestern's Center for Circadian and Sleep Medicine and Center for Sleep and Circadian Biology (CSCB) say increasing artificial illumination at night could have wide-ranging negative effects on human health and the natural world.
Quote from Martha Hotz Vitaterna, research professor of neurobiology at Northwestern's Weinberg College of Arts and Sciences and co-director of CSCB:
"Earth was turning on its axis - causing night and day - when life began. All life forms are adapted to these cycles. Disruption by light at night threatens the well-being of not only humans but the plants and animals with which we share the planet."
