NEW YORK – Joe Soto, general manager of an advertising firm in Philadelphia, has a complicated relationship with his BlackBerry e-mail phone.

He felt “awful” and out of touch when he was without a BlackBerry for two days because his unit fell overboard when he was sailing on the Chesapeake.

At the same time, if he could turn back the clock five years, to before the BlackBerry took over corporate America, he would do it “in a minute.”

“If everybody also threw their BlackBerrys away, I would too,” he said, chuckling. “The only problem is, in my industry, it makes me more competitive.”

A study published Wednesday by the Pew Internet and American Life Project shows that workers in general have mixed feelings about the increased use of e-mail and the Internet in the last few years.

In a survey of 2,134 adults in March and April, 96 percent used e-mail, the Internet or cell phones. Of them, 80 percent said these technologies have improved their ability to do their jobs, and 58 percent said these tools have given them more control over when to work.

But 46 percent also said these devices increase the demands that they work more hours, and 49 percent said that the technologies make it harder to disconnect from work when they should be off.

Half of the respondents who were employed and had e-mail said they check their work e-mail on weekends, and a full 22 percent said they checked office e-mail “often” on the weekends, up from 16 percent who said the same thing in 2002.

Much of the increase can be attributed to increased use of wireless e-mail devices like the BlackBerry, made by Research in Motion Ltd. Of those who have such gadgets, 40 percent say they often check work e-mail on weekends. A quarter often check in even when on vacation.

“The scariest thing was when I was on vacation a couple of years ago, and my BlackBerry rang. I was in the middle of the Sahara Desert!” Soto said.

Checking work e-mail is considered much more important for people making more than $75,000 a year than it is for low earners, just as high earners are more likely to have longer hours. Also those who work for large corporations are much more likely to be checking their e-mail “constantly” at work, compared to those who work for smaller companies.

For workers in general, it's unclear whether e-mail alone is increasing the amount of work. Other studies show that people have worked roughly the same number of hours every week for the last two decades. In the Pew study, 17 percent said e-mail had increased their work hours, while 6 percent said the opposite – that e-mail reduced the time they had to work.

The survey was conducted by phone, and the respondents were called randomly. The margin of sampling error was plus or minus 4 percent.