When it comes to worker productivity, let's face it: Time is money.

The more time your employees spend at work, the better your product is going to be--right?

That's certainly the philosophy behind most productivity tips. As The Atlantic pointed out last month, some start-ups now use perks like in-house dry-cleaning and meal provisions to keep employees at the office longer--and boost profit margins.

"Most CEOs pay lip service to 'work/life balance' in an effort to attract top talent," writes Donna Wells, CEO of the online training firm Mindflash, for VentureBeat. "Here in Silicon Valley, the notion of balance is basically a joke."

However, this is not a simple case of employers taking advantage of niave and perk-blinded workers--younger employees tend to embrace the blurred line between their "work" and "home" lives.

"There is no need for me to keep work life and home life separate," writes Ryan Healy, co-founder of the cloud-based consulting firm Brazen Careerist. "The majority of week nights you can find me in front of the computer chatting with a friend, watching TV and messing around with MySpace or Facebook. I may as well send out an email or finish up a work briefing at the same time."

His sentiment is echoed by employers as well as employees. A recent Global Small Business Survey performed by the PR firm J2, revealed that while 62 percent of small business owners plan to take vacations this summer, nearly two-thirds of them also plan to do work poolside.

In other words, start-up owners are making due with less--time and resources--and may expect their employees to adopt a similarly bootstrapped mentality.

What It's Going to Cost You

The danger of this expectation, writes Wells, is that employees are more likely to get burned out and grow resentful over long hours than, say, a company founder. You may be accustomed to putting your blood, sweat and tears into a project--but that's your job as boss. You want your employees to perform well, but you also want them to be happy--so they will continue to perform well--she writes.

The best way to ensure that your employees perform at sustainable levels of productivity: Enforce occasional down time in company policy, says Wells.

I don't care who tells you different: if your boss is texting you late at night, you feel as if you should be working those hours, too...[At Mindflash] we're regularly tempted to compromise these values due to business challenges and crises and sometimes new employees eager to demonstrate their passion and commitment by working crazy hours on a key project.

But the team invariably self-manages back to our values in simple, but effective ways: people pulling late nights don't get held up as heroes and they may even get a message from their boss saying that working crazy hours is not a company value.

People who are late to or miss a morning meeting because they were burning the midnight oil get penalized through whiteboard eraser duty, which is the developers' equivalent to cleaning the latrines. And unless there's an urgent customer issue, we don't ping each other after hours and late into the night, as was common at my previous three start-ups.