Everywhere you look, people are looking at screens, and then half an hour has gone by before they realize it.

Researchers at the University of Washington conducted in-depth interviews to learn why we can't stop checking our phones. They found a series of reasons, common across age groups, thatstart and end habitual smartphone use. Hiniker and her team interviewed three groups of smartphone users: high school students, college students and adults who have graduated from college. The 39 interviewees were smartphone users in the Seattle area between the ages of 14 and 64.

In general, interviewees had four common reasons for using their phones:

■During unoccupied moments, like waiting for a friend to show up.

■Before or during boring and repetitive tasks.

■When in socially awkward situations.

■When they are expecting a message.

The group also had common reasons that ended their phone use:

■Meeting competing needs from the real world, like meeting up with a friend or needing to drive somewhere.

■Realizing that they had been on their phones for half an hour.

■Coming across content they'd already seen.

The team was surprised to find that the reasons were the same across age groups. "This doesn't mean that teens use their phones the same way adults do. But I think this desire to turn back to your phone plays out the same way across all these groups. The high school students would say ‘Anytime I have a dead moment, if I have one minute between classes I pull out my phone. ' Andthe adults would say 'Anytime I have one dead moment, if I have one minute between seeing patients at work. I pull out my phone.'"