Excessive working hours have negative consequences for employees’ health. Looking deeper into this problem, this article examines how employers’ needs for more intense working or more flexible working hours affect their employees’ psychosomatic health. A German representative survey of 13,452 full-time employees found that long working hours, work intensity (deadline and performance pressure) and flexibility requirements (permanent availability, changes in working hours) were significantly related to psychosomatic health complaints. When considering future work design and practices, these findings show which unfavourable working conditions are to be avoided to maintain the psychosomatic health of employees.