Memorial Day weekend marks the beginning of summer and all it evokes: vacations, slower workweeks, casual dress codes, getting the pool ready and pulling out the outdoor furniture.

It would seem an ideal time to take a break, but our ability to unplug and relax is under assault. A three-day weekend? We can barely get through three waking hours without working, new research shows. The average smartphone user checks his or her device 150 times per day, or about once every six minutes. Meanwhile, government data from 2011 says 35 percent of us work on weekends, and those who do average five hours of labor, often without compensation—or even a thank you. The other 65 percent were probably too busy to answer surveyors' questions.

There's plenty of debate among economists and psychologists whether the economy is to blame, or we do this to ourselves. There's little arguing that the concept of a Sabbath is in serious danger.

"It's like an arms race … everything is an emergency," said Tanya Schevitz, spokeswoman for Reboot, an organization trying help people unplug more often. "We have created an expectation in society that people will respond immediately to everything with no delay. It's unhealthy, and it's unproductive, and we can't keep going on like this."

There's a long list of horribles associated with our new, always-on-digital lives: You are dumber. You are more stressed. You are losing sleep, and more depressed.

People seem to know they need tech breaks, which have plenty of cute names now, like "Digital Detox" or "Tech Sabbath." Consumers pay for software like "Freedom," which cuts their computers off the Net for a pre-set amount of time (really, you could just unplug yours). Reboot even sponsors a National Day of Unplugging, which will occur in March next year. But no one seems to think the problem is getting any better.

It's easy to blame the economy. Workers competing for too few jobs feel like they can't say no to their boss, even if it's a trivial request during a long weekend. It's equally easy to blame gadgets, particularly smartphones, which have virtually tethered employees to their desks. It took labor unions 100 years to fight for nights and weekends off, some say, while smartphones took them away in about three years.

But those explanations are, at a minimum, incomplete. Some experts think these wounds are self-inflicted. Laura Vanderkam, who recently published the eBook, "What the Most Successful People Do on the Weekends," says that many executives she's worked with have learned they can unplug for a weekend without dire consequences.

"Many of us have an exaggerated sense of our own importance," she said, speaking on the eve Memorial Day weekend. "I can tell you that come Tuesday morning, the Earth will still be revolving, whether you have checked your email or not."

Besides driving each other crazy, we are also robbing our brains of critical downtime that encourages creative thinking when we skip weekends and vacations. At extreme levels of exhaustion, rest-deprived brains experience memory loss and hallucinations. But without regular rest, brains fail at more basic tasks. A study at the University of California, San Francisco, found that new experiences fail to become long-term memories unless brains have downtime for review.

Vanderkam also argues that taking breaks makes you more focused when you work. People who work 50 or 60 hours rarely get more done than people who work 40 hours, she argues.

Reboot's vision is a digital-age Sabbath, Schevitz said, but as she explained it on the phone, she was interrupted by a text message. ("Even I struggle with this," she confessed.)

"We need a modern day-rest that brings balance back to life," she said.

Memorial Day weekend is a good time to start. She urged people to start small. Don't try to go 72 hours without e-mail; begin by promising your family one tech-free meal every day this weekend.

"I think that a three-day weekend provides a unique opportunity for people to unplug and decompress because there is a tradition of people going away. So the expectation by the boss that you will be reachable at a moment's notice is likely to be less," she said. "I do think there's hope. When people are given achievable steps, they start seeing that there's a difference."

_By Bob Sullivan of NBC News