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.

He was a reserve player at Derby before his career was ended by injury.
Guthrie became the Rams' trainer and then kit manager, working with more than a dozen managers including Brian Clough over the course of six decades.
He was appointed an MBE in 2009 for services to football and has a stand named after him at the iPro Stadium.
Despite falling ill four years ago, he was still a regular on match days and usually sat in his familiar seat in the home dugout until very recently.
"It goes without saying everyone at Derby County is saddened to learn of the passing of Gordon," said Sam Rush, the club's president and chief executive.
"Our thoughts and condolences are with Gordon's family and friends at this time."
A minute's silence will be held in memory of Guthrie prior to Derby's EFL Cup third-round tie against Liverpool on Tuesday.
Former striker Andy Garner, who began his career at Derby and more recently was part of their coaching staff, said Guthrie was like a father figure to youngsters at the club.
"I found it quite daunting, being a young man and coming to Derby from a small village," Garner told BBC Radio Derby.
"Although I was a big, strong lad, I needed somebody like Gordie. I was lonely at times and he definitely helped me.
"It was a joy for me. I absolutely loved my two-year apprenticeship and Gordie was always there for us. The players and the staff all loved him being there."

The UK financial regulator will hand out the fine to the bank over the issue of inappropriate mortgage advice to customers.
The FCA is expected to release further details of its ruling on Wednesday.
RBS, which is 81% owned by the UK taxpayer, declined to comment.
This latest fine will be another setback for chief executive Ross McEwan, whose troubled bank made a £8.2bn loss last year.
RBS has already been fined £390m for its part in the rate fixing scandal involving the London interbank offered rate (Libor) and has allocated £3.2bn to compensate customers mis-sold loan insurance.
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.
[NEXT_CONCEPT]
Derby County's longest-serving staff member Gordon Guthrie MBE, who spent more than 60 years with the club, has died at the age of 86.
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Royal Bank of Scotland is to be fined about £15m by the city watchdog the Financial Conduct Authority (FCA), the BBC has learned.