The research claims this is costing employers £460 million a day in lost wages.
The research found young people are most likely to be absent due to stress, with almost a quarter (24%) of 18-24-year-olds calling in sick with stress in the last year.
Young employees are most stressed about the possibility of redundancy, with 36% saying they were worried about losing their job. In addition, young people are worried about money (35%) and work (22%).
The research found men are more likely to be stressed due to work than women, with 31% of men saying work causes them the most stress, compared to 23% of women.
David Williams, director of group protection at Friends Life, said: “UK economic output is improving but this is not having as positive an effect on UK workers’ stress levels as we would have hoped.”
He added: “It is important that employers spot the signs of stress early to ensure that appropriate action can be taken to help employees feeling pressurised. This can positively affect employee wellbeing, engagement as well as business productivity.”
Today is National Stress Awareness Day.
