The Mobile Consumer Habits survey conducted online by Harris Interactive for Jumio Inc. also found 1-in-5 younger adults ages 18-34 admitted to using their smartphone during sex.
In addition, 12 percent of U.S. adults said they used their smartphone in the shower and 19 percent at church or other place of worship.
The survey was conducted June 13-17, among 2,021 U.S. online adults, of whom 1,102 respondents were smartphone owners/users age 18 and older.
"People view their smartphones as an extension of themselves, taking them everywhere they go -- even the most unorthodox place," Marc Barach, chief marketing and strategy officer at Jumio, said in a statement.
Nearly three-quarters of respondents reported being within 5 feet of their smartphones the majority of the time.