Older workers tend to be more unhappy in their jobs than their younger colleagues, according to a survey of more than 2,000 U.K. employees by human resource firm Robert Half U.K. One in six British workers over age 35 said they were unhappy -- more than double the number for those under 35. Nearly a third of people over 55 said they didn't feel appreciated, while 16 percent said they didn't have friends at work. From a report: There's the stress of being in a high-ranking position -- or the disappointment of not making it far enough up the career ladder. True, salaries are higher, but life starts to get more expensive. "Work-life balance" starts to mean taking care of children, rather than just personal stress management. "There comes a time when either you haven't achieved success, work has burned you out, or lived experience tells you family is more important," said Cary Cooper, a workplace researcher at Manchester Business School. "You ask yourself: 'What am I doing this for?'"