Two surveys published by PCS this week found high levels of stress, longer working hours and fewer opportunities to achieve a work-life balance among civil servants.
Of those civil servants who responded late last year, almost three-quarters stated that their workload has increased, with 74% of these blaming staffing cuts.
One third of civil servants asked said that their hours have increased since 2012 and almost 6% estimated that on average they work more than 48 hours a week.
Whilst almost 65% of those who responded stated they had suffered from stress related ill health, 60% did not believe their employer had helped them cope with the causes of stress.
According to the PCS, the latest surveys show that conditions for civil servants have worsened since the union's first stress survey was carried out in 2006.
PCS general secretary Mark Serwotka said: “The government has no claim to be a model employer when it is causing such high levels of stress, ill health and overwork."
A Cabinet Office spokesperson said: "We need an exceptional Civil Service delivering the best public services at the best value for taxpayers. Our latest survey of 270,000 staff, showed that the Service is a good place to work and morale has held at 2009 levels.
Nine out of ten are interested in their work and more than before would feel supported in trying a new idea, even if it doesn't work. We are pushing ahead with reforms to improve performance, drive up efficiency, and enrich our employees’ careers.”