In our lives we're exposed to lots of artificial light, including blue light from our screens, like phones and tablets. Previous research has found that this blue light can affect the body clock and hormones that govern sleep. For a new study, scientists looked at teens-- one group was instructed to refrain from using their phones 20 minutes before bed, and the other group had to wear special glasses that block out blue light in the same time period. After one week of this, both groups fell asleep and woke up earlier than before the trail started. The scientists plan to see if the same thing would work to help adults sleep better.