There are benefits to remote work, of course. Working from home can relieve the stress of a commute. Parents of young children can leave the office early, pick up the kids at day care and then finish their tasks after a family dinner.  "Moving away from a 9-to-5 workweek may not be possible for some companies ... but if done right, allowing employees more freedom and flexibility with their schedules can improve morale, boost productivity and increase retention rates," said Rosemary Haefner, chief human resources officer at CareerBuilder.  But blending these worlds together brings all sorts of well-known hazards. Overwork brings with it increased risk of heart disease, diabetes and depression, according to a study published in the American Journal of Epidemiology, while "binge" working has even killed workers in extreme cases. Overwork isn't great for employers, either. Tests show workers have impaired cognitive skills when working nine- to 12-hour days, and worker effectiveness falls off the cliff after 50 hours of work during the week.  Working outside of traditional hours or offices can also interfere with personal relationships.  "I spoke recently with a gentleman who works for a state government agency and he told me that he is constantly on Twitter on his phone after normal work hours," said Russell Clayton, a management professor at St. Leo University. "He told me that in the evening he will use one hand to catch a ball thrown by his toddler son and use his other hand to scroll through Twitter."  While it's possible to tweet and play catch—at least, if you're well-coordinated—most people wildly overestimate their ability to multitask. Stanford University research found that folks who described themselves as expert multitaskers actually performed worse on cognitive tests than the general population. Most experts agree that, with rare exceptions, "multitasking" is really just rapid toggling between tasks, which brings with it switching costs ("Now where were we?") that make the whole affair much less efficient.  Read MoreWhy you should never work more than 50 hours a week
A new CareerBuilder survey finds workers are having an increasingly hard time separating their professional and personal lives.