"I just don't have time to do everything I need to. I'm behind checking my e-mail. My voice mail is full. I'm constantly thinking about what I need to do!"

Sound familiar?

In his book, "The Myth of Multitasking: How Doing it All Gets Nothing Done,'' business coach Dave Crenshaw debunks the value of multitasking -- a habit he prefers to call "switchtasking."

"Research provides neurological evidence that the brain cannot effectively do two things at once," said Crenshaw. "Multitasking is a polite way of telling someone 'I haven't heard a word you've said.'"

Switchtasking, Crenshaw says, is a less effective and less efficient way to get things done.

"'Switching costs results when people must go back and review what they've done before they resume work on a task. The more complicated the task, the greater the cost," he said.

"Saying you are good at multitasking is like saying you're good at using a less effective method of getting things done," he concludes. "No matter how good you are at switchtasking, you will get less done than the person who focuses on one attention-requiring activity at a time."

Renee Marois of Vanderbilt University agrees. "We will never be able to overcome the inherent limitations in the brain for processing information while multitasking. It just can't be done, any more than the best of all humans will ever be able to run a one-minute mile," she writes.

But can multitasking be unlearned?

Peter Bregman writes in the Harvard Business Review about his one-week experiment to give up multitasking. "I wanted to know if I could sustain focus on one thing at a time for that long."

His answer: a resounding "Yes."

Bregman cites six discoveries from his experiment:

• Being free of multitasking was delightful.

• I made progress on challenging projects.

• My stress level dropped dramatically.

• I lost patience for things that wasted my time.

• I had patience for useful and enjoyable tasks.

• There was no downside.

"I lost nothing by not multitasking," Bregman says. "No project was left unfinished. No one was frustrated with me for not answering calls or failing to return e-mails the second I received them. I found no downside, so why don't we all stop?"

Bregman notes that the best way to avoid interruptions is to turn them off.

"When I write," he said, "I disconnect my computer from the wireless and turn off my phone. In the car I leave my phone in the trunk."

Drastic? Maybe. Bregman offers these tips to make it work: "Use the loss of patience to your advantage. Create short deadlines. Cut meetings in half. Give yourself the time needed to accomplish goals."