Managers who inspire their staff to perform above and beyond the call of duty may actually harm their employees' health over time, according to researchers from the University of East Anglia (UEA).

The findings suggest that constant pressure from these 'transformational leaders' may increase sickness absence levels among employees. They also indicate that some vulnerable employees in groups with transformational leaders may in the long term have increased sickness absence rates if they ignore their ill-health and frequently show up for work while ill, known as presenteeism.

The study, published in the journal Work & Stress, was led by Karina Nielsen, professor of work and organisational psychology, and Kevin Daniels, professor of organisational behaviour at UEA's Norwich Business School. They looked for the first time at the relationship between presenteeism, transformational leadership and sickness absence rates. The results have implications for how organisations might effectively deal with employees' health and well-being.

Transformational leadership has previously been associated with positive employee well-being, better sleep quality, fewer depressive symptoms and reduced general absenteeism in the short term.

However, the new study suggests that a transformational leader who encourages their group to make an extra effort at work may exacerbate sickness absence, as high levels of presenteeism may result in reduced opportunities for recovery along with the risk of spreading contagious conditions, such as the common cold, in the long term.

Prof Nielsen said the relationship between transformational leadership and sickness absence was complex.

"It is possible that high performance expectations pose a risk to both healthy and vulnerable employees and the motivational aspects of transformational leadership may backfire," said Prof Nielsen. "Transformational leaders may promote self-sacrifice of vulnerable employees for the greater good of the group by encouraging them to ignore their illnesses and exert themselves. This can lead to increased risks of sickness absence in the long term.

"Such leaders express values to perform above and beyond the call of duty possibly at the expense of employees' health because they have a self-interest in demonstrating low sickness absence rates in their work groups. This pattern may be a particular problem in organisations where managers are rated according to their ability to control sickness absence levels."

The research focused on postal workers and their managers in Denmark over three years. In total there were 155 participants in 22 work groups. Employees rated their immediate line manager at the start of the study and were asked about their sickness absence and presenteeism for the previous year. Sickness absence was assessed again in years two and three.

The authors found that transformational leadership increased sickness absence when workers exhibited 14 more days of presenteeism than their colleagues. Transformational leadership in the first year was related to higher levels of sickness absence among staff in the second year, but not the third. Employees working in groups with a transformational leader and who had high levels of presenteeism reported the highest levels of sickness absenteeism in the third year, but not the second.

The findings suggests that more immediate, short term effects can be found among staff, but for vulnerable workers, such as those with high levels of presenteeism, increasing adverse effects take longer to materialise. Lack of recovery time may also explain this effect, leading to them eventually having to go off sick because they can no longer ignore their symptoms.

Prof Daniels said: "The assumption that 'more transformational leadership is better' does not hold over time. As role models, transformational leaders should display healthy behaviours when motivating people, they should monitor and check them, and encourage workers to look after their own health. Managers need to strike a balance, they can still encourage staff to perform well, but in a way that is not at the expense of their health and well-being."

The authors recommend that transformational leadership training should include health-related elements. For example, intellectual stimulation should not only focus on developing competencies but also on building resilience and coping skills. Leaders could also be trained in incorporating well-being and health into the vision, goals and objectives they develop for work groups.