A BBC freedom of information request to the force revealed 4,789.27 days were recorded in 2010, compared to 12,198.48 in 2014, an increase of 155%.
Overall sickness went up by 60% in the same period. The force employs 1,939 officers and 1,568 staff.
West Mercia Police Federation said the figures suggest a link to funding cuts.
The number of employees off with anxiety and stress in 2010 was 134 but rose to 229 last year, representing a 70% increase.
Days lost because of sickness and ill health overall totalled 24,419.89 in 2010 compared with 39,022.75 in 2014, a 60% rise.
The force has not said how much the absences have cost.
West Mercia Police and Warwickshire Police announced plans to form an alliance in 2011, which came into effect in 2013.
They two forces started a three-year plan to cut spending by Â£30m in 2012.
Russell Yeomans, chairman of the West Mercia Police Federation, said: "On the face of it, it's difficult to say but the figures suggest that there is a direct link to the cuts and the extra responsibilities police officers have faced but it could be difficult to say that based purely on these figures."
He said police numbers had dropped over the past five years, a trend which was going to continue.
An ongoing recruitment campaign would only replace officers leaving, he said.
"Policing is and always will be a stressful profession," he added.
West Mercia Police said it recognised the figures showed a rise in sickness absence, particularly for anxiety and stress and a number of measures were already in place to provide support.
"A new action plan has been implemented in the past year and additional training has recently become available for line managers to help them support their staff," the force said.
The number of days lost by West Mercia Police employees through depression or anxiety problems has more than doubled between 2010 and 2014, figures show.