Cell phone users who are separated from their devices experience serious psychological and physiological effects, according to a study conducted by researchers from the University of Missouri.

The study, published in the Journal of Computer-Mediated Communication, was designed to better understand the impact of cell phone usage and what occurs when people are unable to answer their ringing phones.

Involved iPhone users who were told that the purpose of the study was to test out a new wireless blood pressure cuff. In reality, researchers observed and recorded heart rate and blood pressure data as study participants sat at a cubicle. While at the cubicle with their iPhone in their possession, participants completed a word search puzzle. Researchers then asked participants to complete a second word puzzle without their iPhone.

As they completed the first puzzle, researchers recorded each patients’ heart rate and blood pressure responses. Then, researchers informed the participants that their devices were causing interference with the wireless blood pressure cuffs and that they would need to place the phones further away in the room for the rest of the experiment. Finally, as participants worked on the second puzzle, the researchers called the participant’s iPhones and the measure the blood pressure and heart rates of the participants.

Researchers found that when participants were unable to answer their ringing iPhones while solving the word puzzles, their heart rate and blood pressure jumped. In addition, the participants feelings of anxiety and unpleasantness increased.

“Our findings suggest that iPhone separation can negatively impact performance on mental tasks,” said Russell Clayton, lead researcher. “Additionally, the results from our study suggest that iPhones are capable of becoming an extension of ourselves such that when separated, we experience a lessening of ‘self’ and a negative physiological state.”