PALO ALTO, Calif. — Researchers with the Stanford Institute for the Quantitative Study of Society plan to publish a new study on their website Monday, indicating that people displace time usually reserved for other activities with Internet usage.

The study, a followup to the group’s 2000 study that reported increased physical isolation among Internet users, suggests that time spent using the Internet decreases the amount of time used for watching television, interacting with friends and family, and even shortened sleep periods.

According to a preliminary analysis of the study, an hour of Internet usage takes the place of face-to-face contact with friends and family by about 23.5 minutes, television watching by 10 minutes, and sleep by roughly 8.5 minutes.

“People don’t understand that time is hydraulic,” Norman H. Nie, director of the institute, told the New York Times.

The study does not draw conclusions about whether Internet usage hurts or strengthens social relationships, however, and did not show significant difference between the Internet use by gender, although it does suggest that women spend more time using email and men more spend time browsing websites and using chat rooms.

Age difference noted in the study include younger individuals using instant messaging more often than older people, who favor email.

The majority of Internet use, roughly 57 percent, was devoted to communication activities like using email or instant messaging, according to the survey, and roughly 8.7 percent of time on the Internet was related to online game playing.

Internet use seems to also be widespread throughout the U.S. population, with roughly 75 percent accessing the Internet either at home or on the job.

“It is remarkable that this expansion of use has happened in just a decade since the invention of the web browser,” Nie said.

Almost a quarter of an hour every day was spent dealing with computer problems, according to the study.

Preliminary findings of the study will be available on the institute’s website on Monday.