Generation X isn’t getting much sleep lately — maybe that’s why American Funds has labled them “Generation AnXious.”

According to recent research from the Los Angeles-based active investment manager, Gen Xers, now between the ages of 37 and 51 years old, is feeling the most stressed by planning their financial future.

In “The Wisdom of Experience: Lessons Learned from Millennials, Generation X and Baby Boomer Investors,” 63 percent of generation X respondents said that they were kept up at night thinking about financing their retirement. Around half of the survey’s other respondents felt the same: 53 percent of millennials ages 21 to 36, and 45 percent of baby boomers aged 52 to 70, are kept up at night by their retirement concerns.

More than 30 percent of Gen Xers in the survey felt worried that they’re not earning enough money to be able to invest for the future, and around one-quarter are concerned that they will not be able to pay off their own debts and finance their children’s aducation.

All that uncertainty makes Generation X more likely to seek outperforming mutual funds, said Heather Lord, senior vice president and head of strategy and innovation at American Funds’ parent company Capital Group, in released comments.

"After experiencing the dot-com bust, the global financial crisis and the housing collapse, as well as stagnant wage growth during their formative adult years, Gen Xers are wary about their financial future," said Lord. "Perhaps because of these concerns, Gen Xers long to do better than the average market and say actively managed funds can help them reach these goals.”

Age and gender played a role in respondents’ views about the future.

Men were more confident than women that the market would continue to go higher over the next decade -- 67 percent of male respondents expect the market to continue its rise compared to 51 percent of female respondents.

When asked about their outlook over the next 25 to 30 years, on the other hand, women in the survey displayed levels of optimism on par with men. Fifty-seven percent of both sexes said that they expected the market to continue to go higher over the next two to three decades.

Over the next decade, only 16 percent of baby boomers expect the markets to repeat the relatively strong returns of the past five years. Millennials were nearly twice as optimistic -- 31 percent believed that the market would continue its run over the next decade.