WASHINGTON, April 23 -- Getting around without Google Maps. No longer scrolling Instagram at the bus stop. Ditching your headphones to hear the birds sing.

In March, a group of 20- and 30-somethings in the US capital swapped their smartphones for basic flip phones and embarked on a one-month digital detox, part of an emerging movement of young Americans seeking to break free from the harmful effects of social media.

"I was waiting for a bus, and I didn't know when it would come," recalled Jay West, 29, who took part in the Month Offline challenge organized by a small startup with support from a local community group.

Old habits die hard, and West, who works as a data analyst for Washington's metro system, said he would often find himse...