Turn out the lights
In the last few hundred years, human beings have dramatically altered our nighttime environment by removing the darkness, especially in cities. It's now becoming clear that this not only has substantial negative effects on creatures like insects and bats, but also on humans — both on our astronomy and our health.
Hank Green explains below.
On a more positive note, a study found that spending a week camping rapidly re-syncs one's sleep cycle with the rising and setting of the sun, which may help counteract some of these effects. Though more research is needed, it's another reason to get outdoors when you can.