This post comes from Seth Fiegerman at partner site MainStreet.

The era of a 9-to-5 workday appears to be coming to an end.

Higher-level workers are increasingly being asked to put in 50 hours or more a week, effectively working an 8-to-6 day at the very least, while lower-income workers are often forced to work fewer hours but at jobs with irregular schedules, according to a comprehensive report from the Center for American Progress (.pdf file), which reviewed dozens of studies from the previous 30 years to understand the changing work/life struggles of the country's labor force.

Driving these changes, as the center explains it, are companies turning lower-level full-time jobs into part-time employment to cut costs, savings that come at the expense of workers -- and their families -- losing the traditional schedules and financial benefits that come with full-time employment.

At least 50 hours

Some 38% of men in professional and management positions worked at least 50 hours a week between 2006 and 2008, up from 34% who worked those hours 30 years prior, based on government studies cited in the report. Women in higher-level positions experienced an even steeper change, with 14% working 50 hours or more in 2006-2008 compared with just 6% who did between 1977 and 1979.

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These longer work schedules, which the center describes as being "ramped-up versions" of what full-time employment once meant, were found to be particularly common on the higher end of the income ladder.

"Many of the highest-paying and highest-status professional jobs require very long hours -- and, in today's 'winner take all' economy, turning them down can extract a sharp wage penalty," the researchers write in the report. Post continues after video.

Much has been written about the number of Americans forced to work longer hours in the aftermath of the recession, as companies cut their payrolls, but as the literature reviewed in this report shows, many higher-level professionals were in danger of becoming workaholics long before that. One Harvard study published in 2006, for example, found that a fifth of those in the top 6% of income earners actually worked 60-hour weeks on average.

On the other hand, lower-level workers are facing the opposite problem. The percentage of men in low-income professions who worked 50 hours a week was cut in half during the previous 30 years, despite the fact that these workers often want to put in more hours to build up their income. To make matters worse, though they work fewer hours, their schedules tend to be more irregular, with two-thirds of couples who earn less than $50,000 a year having at least one spouse who works hours outside the traditional 9-to-5 schedule (i.e., nights and weekends).

This change in schedules for high- and low-level employees not only has the potential to cause added stress while at work but, according to the report, it also has the potential to cut into the time these people would otherwise spend taking care of their households.

Companies lose

Even the companies themselves may not benefit in the end from pushing more inconvenient work schedules. As the center points out, one survey found that workers would be 30% less likely to quit their job within the first two years if they had flexible schedules. However, since their schedules are getting worse, not better, companies may have to confront higher turnover and the added financial burden that comes with replacing employees.

Despite the changes to the nation's overall work experience, there are plenty of companies that do provide flexible schedules and other perks to lighten the burden of a heavy workweek. To find a few of the best options out there, check out MainStreet's roundup of the companies with the healthiest work/life balance.

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