As work schedules and expectations increasingly become more flexible, those long or odd hours may have a more negative impact on a woman’s health than a man’s, according to a new study.

A study of workers in the United Kingdom, led by academic staff at University College London and published in the Journal of Epidemiology & Community Health, found that women working long hours or outside normal office hours — defined as 55 or more hours per week as well as working on weekends — were significantly more likely to display depressive symptoms than those who worked fewer hours, Quartz reported.

Men in the study tended to work longer hours than the women, with almost half working longer than the standard working week of 35 to 40 hours. Fewer than a quarter of women worked over the standard week hours. Among men, working even the longest hours wasn’t associated with any significant increase in depressive symptoms.

More than two-thirds of men and half the women worked weekends. Working weekends did have an effect on men’s well-being, but only when considering other factors such as being unhappy with their pay or job. 

Data for the study were taken from the UK Household Longitudinal Study, focusing on a subset of data from 2010 to 2012 that included 11,215 men and 12,188 women.

Read the full study online.