The big push in office design is forcing co-workers to interact more. Cubicle walls are lower, office doors are no more and communal cafes and snack bars abound.

Like most grand social experiments, though, open-plan offices bring an unintended downside: pesky, productivity-sapping interruptions.

The most common disruptions come from co-workers, as tempting as it is to blame email or instant messaging. Face-to-face interruptions account for one-third more intrusions than email or phone calls, which employees feel freer to defer or ignore, according to a 2011 study in the journal Organization Studies.

Other research published earlier this year links frequent interruptions to higher rates of exhaustion, stress-induced ailments and a doubling of error rates.

It's easy to turn to a neighbor for, say, tips on how to tweak a spread sheet or where to go for lunch. But such interruptions -- which many feel it would be rude to rebuff -- nibble away at the ability to stay on task.

There's a range of compensating behaviors. Some wear headphones. Some invent 'do-not-disturb' signals like wearing hats or armbands, or stretching yellow barricade tape around their cubicles. More employers are training co-workers to communicate differently, and to limit unscheduled meetings.

Employees in cubicles are interrupted 29% more often than those in private offices, research from the University of California, Irvine, shows. Intercubicle traffic at one telecommunications company peaked daily from 2:30 p.m. to 4 p.m., when employees played music, talked over cubicle walls or walked among each other's desks, according to the research published in Organization Studies.

Such patterns can be costly. Employees who experiencedfrequent interruptions reported 9% higher rates of exhaustion -- almost as big as the 12% increase in fatigue caused by oversize workloads, according to a survey of 252 working adults published recently in the International Journal of Stress Management. Interruptions also sparked a 4% increase in physical ailments such as migraines or backaches, says the study.

Error rates skyrocket after interruptions. Participants in a recent 300-person study were asked to perform a sequence of computer tasks, such as identifying with a keystroke whether a letter was closer to the start or the end of the alphabet. After even a brief interruption of about 2.8 seconds, when they were asked to type two letters, the subjects made twice as many errors, says the study in the Journal of Experimental Psychology: General.

'Two seconds is long enough to make people lose the thread,' says Erik Altmann, a psychology professor at Michigan State University in East Lansing, and the study's lead author.

To make matters worse, it takes more than 25 minutes, on average, to resume a task after being interrupted. After resuming a complex task such as design or programming, says Tom DeMarco, co-author of 'Peopleware,' a book on productivity now in its third edition, it takes an additional 15 minutes to regain the same intense focus or 'flow' as before the interruption, based on an 800-employee study for the book.

While another study by Dr. Altmann found people working in controlled laboratory conditions were capable of getting back up to speed on complexcomputer tasks within 15 seconds of being interrupted, few people actually dive right back into a demanding task after an intrusion. Most employees attend to two or more other tasks first, research shows. 'It takes effort to get back into it. That work is aversive, so you start checking your email,' Dr. Altmann says.

In some professions, breaks in concentration can result in serious consequences. Nurses at 24 Kaiser Permanente hospitals wear bright-colored sashes or vests to prevent interruptions while they are preparing medications for patients, says Scott Heisler, a registered nurse and innovationspecialist for the nonprofit health plan and hospital system based in Oakland, Calif.

Some Kaiser hospitals also mark off 'no-interruption zones' near medication dispensaries, using red floor tape or different-colored floor tiles, he says. Mr. Heisler says Kaiser got the idea for the program from federal regulators' 'sterile-cockpit rule' for the airline industry, which prohibits interrupting pilots during critical times, such as takeoffs and landings.

A variety of quirky solutions are being marketed to cubicle dwellers. CubeGuard, of San Jose, Calif., makes neon-yellow plastic 'do not disturb' barricade tape, to block off cubicle entries.

More than 6,500 workers each year download a free 'Interrupters' Log Worksheet' from MindTools.com, a career-skills website, to help them analyze the sources of interruptions and either eliminate or reorganize them to save time, says James Manktelow, chief executive of Mind Tools.

One way people can dive back into a task more quickly and reduce errors, research shows, is by bookmarking their place, marking the next step with a large, bright symbol such as a red arrow.

Laura Stack, a Denver productivity trainer and author, suggests asking an interrupter to wait while you record your last thought on a sticky note, then posting the note on the page or screen to mark where you stopped working. The visual cue can cut the time needed to restart a task by as much as 80%, she says.

Ms. Stack also trains employee teams in triage -- learning to interrupt each other only when a problem is a top priority. For less-important matters, employees often can send a meeting request.

Sheri Caldwell says she saves time using another strategy recommended by Ms. Stack -- telling interrupters she'll meet them a few minutes later in their own office. That lets her complete the task she's working on, and take control over the length of the meeting. 'Not only can you do it on your schedule, but you can leave when you want to,' says Ms. Caldwell, a human-resource manager for a Toledo, Ohio, insurance firm.

Maura Thomas, an Austin, Texas, speaker and trainer on productivity, suggests breaking the habit of jumping up to talk to a colleague any time a question comes up. Instead, she advises keeping a separate 'talk-to' list of topics for each colleague, then waiting until you have several items and setting a meeting.

Sometimes there is no replacement for a door that closes. Schaefer Advertising recently moved its Fort Worth, Texas, headquarters into new open-plan offices in a remodeled apartment building. The agency's 16 employees can talk and move freely among each other's desks.

But the agency also walled off three former patios on the front of the building to use as 'privacy rooms.' Account supervisor Erin Naterman retreated to one last month so she could gather her thoughts and write a business proposal. If a co-worker enters and closes the door, she says, 'we know they don't want to be interrupted.'

Barring an emergency, Ms. Naterman says, 'we wait for them to come out.'

Sue Shellenbarger