As you know, your smartphone knows just about everything. It can give you turn-by-turn directions around the Phoenix metro area, and it can play songs and games, show movies, answer questions, give advice and yes, it can even make phone calls.

You can add one more thing to the list of amazing things your smartphone can do: it can tell when you have had too much to drink. According to a new study in the Journal of Studies on Alcohol and Drugs, by detecting changes in your walk, you phone can determine if you have consumed too much alcohol.

Can it reduce the risk of a DUI?

Researchers say that real-time information about impairment will be useful in many ways, including reducing the risk of being arrested for driving under the influence (DUI).

Lead researcher Brian Suffoletto, M.D., said, “We have powerful sensors we carry around with us wherever we go” that can help us avoid risky behavior.

A drink for science

He and his colleagues recruited 22 adults aged 21 to 43 for the study. Volunteers were given a mixed vodka drink strong enough to produce a breath alcohol concentration (BAC) of .20 percent. (It should be noted that Arizona’s drunk driving threshold is .08 percent. A driver with a BAC of .20 percent can be charged with Super Extreme DUI.)

For the next seven hours, the volunteers had their BAC analyzed hourly. They also performed a walking task with a phone attached to their lower backs, taking 10 steps in a straight line, turning and then taking 10 steps back.

Measuring movements

The phones measured acceleration and measured three types of movements: side-to-side, up-and-down and forwards and backwards.  Researchers were able to use measured changes in gait to determine when the volunteers’ BAC exceeded .08 percent.

Suffoletto said the controlled study shows that can identify “signatures” of alcohol impairment. He predicts that within five years, people could go out with friends to have drinks, and that their phones will alert them “at the first sign of impairment” and help them to avoid getting behind the wheel.