You will know them by the classic symptoms of withdrawal: anxiety, irritability, twitching hands, maybe a phantom buzz they keep hearing even when it isn’t there.

If a government shutdown comes to pass, the nation’s capital may soon be in the grips of something akin to a mass nicotine fit. Tens of thousands of federal workers deemed “nonessential” will be forced to give up their BlackBerrys.

Government workers have seen furloughs before, but never in the era when so much of their lives and identities has been bound up in a little gizmo that for many seems to have been surgically implanted in their palms.

“My wife and kids would probably like it for a couple of days,” said Kevin Bishop, communications director for Sen. Lindsey O. Graham (R-S.C.), whose mobile device has made it possible for him to do his job from the senator’s Greenville office. “I’m not sure I could handle it, though. It’s basically a part of who you are, from the moment you wake up in the morning to the moment you go to bed at night.”

While Bishop sleeps, it recharges nearby. The only place it doesn’t accompany him is to church.

Under the provisions of a 19th-century law known as the Anti-Deficiency Act, it is quite literally illegal for federal employees deemed nonessential to voluntarily work during a shutdown. In the modern era, that means they can’t use e-mail or voice mail.

How, precisely, the government would enforce that ban has not been worked out. A senior administration official said that one plan under consideration would require nonessential executive-branch workers to surrender their government-issued BlackBerrys and other electronic devices on the way out the door. However, a top aide at the Office of Management and Budget said that agency has no idea how many personal digital assistants, or PDAs, are even out there.

And short of shutting off employees’ access to their office computer network, it is far from clear how agencies would prevent their furloughed employees from calling in for their voice-mail messages or signing on from their home computers.

Particularly for senior officials, being severed from their devices adds to the indignity and anxiety of being told they aren’t essential.

“You’re talking about people who are used to being in charge and having their own careers advance because they are on top of things,” said Paul DeCamp, who was administrator of the Labor Department’s wage and hour division during the George W. Bush administration.

On Capitol Hill, the rules are likely to be more haphazard, with lawmakers having some discretion as to whether people on their staffs would have to work and, if so, how many. In some congressional offices, the guidance is likely to be that staff members may “read but not write” on their devices, said a Senate committee staffer who had been briefed on the shutdown procedures but declined to be identified.

The strain of giving up access to BlackBerrys may be greater on younger staffers, who have never known any other way of living.

“I’m of an age where I remember not having a BlackBerry. I’d be fine, thanks,” said Bill Dauster, deputy chief of staff to Senate Majority Leader Harry M. Reid (D-Nev.) Still, Dauster said, “I do have to wonder how they would get the word out that people have to come back to work, if they can’t look at their BlackBerrys.”

At the Senate Homeland Security and Governmental Affairs Committee, communications director Leslie Phillips said that staff deemed nonessential should monitor their BlackBerrys in case of an emergency that would make them essential or if an issue needs to be brought to the attention of those who are on duty.

The trauma of severing the electronic umbilical cord is an issue that has come up often in recent years in the private sector, where furloughs became more frequent during the recession, and where wage-and-hour laws have required employers to ban workers’ use of PDAs during that time off.

“People have gone nuts, not only being without it, but also because so much of their lives are intertwined with it,” said Gayle Porter, a Rutgers University professor and expert on workaholism. In 2006, she co-authored a study that found that workers develop an addiction to their PDAs — “technophilia,” not unlike alcoholism — that merits treatment.

Add to that the practical fact that, for many people, the BlackBerry organizes their daily schedule, contains the information they need to reach everyone who is important to them and is even the number their children know to call in an emergency.

That is why many government workers spring for a second cellphone or PDA for personal business. They often carry a BlackBerry for official matters and an iPhone or Droid for everything else.

Still, furloughed workers know that somewhere out there in the electrons, their e-mail inbox is growing fuller by the hour.

“It’s a nightmare,” DeCamp said. “They’re dealing with time-sensitive projects. It’s not like their deadlines cease to apply. The tide keeps coming in.”

And that might be the hardest part of all for furloughed federal employees: knowing that they would have to mop up a flood when they get back to work.

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Staff writer Sandhya Somashekhar contributed to this report.