Our smartphones supply endless possibilities for entertainment, but a new study shows they can diminish the quality of users' time away from work or school.

"The high-frequency cell phone user may not have the leisure skills necessary to creatively fill their free time with intrinsically rewarding activities," says Dr. Andrew Lepp, of Kent State University. "For such people, the ever-present smartphone may provide an easy -- but less satisfying and more stressful -- means of filling their time."

Lepp and his team worked with a participant group of 454 randomly selected undergraduates, quantified each individual's total daily smartphone time and assessed their personalities and notions of leisure.

Separating the students into groups based on their similarities concerning smartphone time investment and personality, the researchers noted three distinct categories were taking shape.

User types included low-use extroverts, low-use introverts and a high-use group who averaged more than 10 hours per day of smartphone time, about 25 per cent of the sample.

This high-use group experienced considerably more stress and anxiety during their leisure time than the other two groups.

For those who can't seem to put down their smartphones, it may not be a question of enjoying them more than others do, the high-use habit could reflect a feeling of obligation to stay connected, according to the researchers.

This obligation can lead to stress, and smartphone-borne stress can spill over into leisure, they say.

On the flip-side, the low-use extrovert group, who used their smartphones on a comparably modest average of three hours per day, expressed very little boredom and distress during leisure time and had a penchant to challenge themselves.

"Being constantly connected to your phone is not likely to enhance your experience of leisure," says Dr. Jian Li of KSU.

"On the other hand, disconnecting for short periods of time in order to seek more challenging leisure opportunities is likely to be beneficial."

The study was published in the journal Computers and Human Behavior.