Your smartphone apps know when you're sleeping, they know when you're awake, and they know what you did last summer and last night. And they're reporting it to advertisers -- and others.
Boston attorney and Professor Steven Weisman says it's not just for targeted ads.
"It could also be exploited by someone who was able to manipulate my opinion on things; it could be used as far as for influencing voting."
But Weisman says you can turn it off in your phone's settings.
"You can go on your phones and delete the data sharing; so you can take control of it. They don't make it easy, but you can."
Weisman says university research shows the data collected shows much more about you than we've thought.
Weisman says studies on students show the data could be used to create a surprisingly accurate profile of your life.
"They were able to plot out so much information about the lives of these students it was incredible; even telling when somebody was breaking up with a boyfriend or a girlfriend."
Professor Weisman says he wasn't too worried about all this data collection until recently, but now he worries about how his personal information, collected by apps, can be used against him.