A 'Blue Light' Epidemic Is Sweeping the Globe and Destroying Our Sleep (4 photos)

A global "blue light" epidemic is sweeping the planet, sabotaging our sleep and sparking mental health issues. Over 23 years of photographing cities from space, NASA astronaut Donald Pettit documented how major metropolises replaced traditional sodium-vapor streetlights with energy-efficient LEDs. This harsh light disrupts natural circadian rhythms and makes falling asleep difficult. Teenagers and people living with depression or bipolar disorder are at particular risk, as exposure to blue light can trigger manic episodes. Earlier studies have also shown that screen glow and cool-toned lighting throw off our internal body clocks, even disrupting women's menstrual cycles.