OAKLAND — For police officers in Oakland and Berkeley, the relentless protests occurring almost nightly the past two weeks have taken more of a toll on their work and personal lives than anything they faced before — even Occupy.

In Oakland — the focal point of the demonstrations until last weekend — the impact isn’t just on the officers manning skirmish lines but on the department itself, officials said. Criminal investigations have stalled, community policing projects have been put on hold and patrol units have been thinned as officers have instead been ordered to deal with the recurring civil unrest.

“The reality is that it has absolutely stretched the capabilities of the police department and that it has taken us away from our core mission of trying to reduce crime here in the city,” Chief Sean Whent said.

It also has severely cut into the officers’ time away from work.

In the 16 days since a Missouri grand jury refused to indict a white officer in the killing of an unarmed black teenager, Michael Brown, there have been 12 protests in Oakland. Patrol officers have had their shifts increased from 10 to 13 hours.

And the police department has canceled all regularly scheduled days off — including weekends — 10 times to make sure enough police were on hand to cover the protests, which are pushing for police to be held criminally accountable for killings, including those of Brown; Eric Garner, a Staten Island man who died from a police choke hold; and Tamir Rice, a Cleveland 12-year-old shot in a public park.

City officials could not provide figures Tuesday on how much police overtime the city has incurred from the protests.

Oakland officers interviewed on condition of anonymity said the overtime isn’t worth the sacrifices they have had to make in recent weeks.

One officer said he has had to cancel Thanksgiving and miss one of his children’s birthday’s to work the mandated overtime. “I leave every day and my kids say, ‘Do you have to stay late again, today?'” the officer said. “There isn’t much you can say. I just try to make it up to them.”

Many protesters aren’t sympathetic to the officers’ plight.

“If we’re going to talk about families, we have to talk about the families of Tamir Rice, Eric Garner and Michael Brown and how they will never be able to spend time with their loved ones again,” said Reiko Redmonde, a staffer at Berkeley’s Revolution Books. “We can’t have business as usual because business as usual right now means the systematic murder of black and brown people by police.”

The major difference between the current protests and those carried out by Occupy Oakland, officers said, is that while Occupy protests were scattered over weeks and months, these protests haven’t stopped.

After protests over the grand jury verdict in the Brown case started to dissipate, the protests began anew last week after a Staten Island grand jury refused to indict a police officer in Garner’s killing. And when those protests seemed to be fading late last week, they suddenly reignited in Berkeley over the weekend after police were viewed as taking too forceful a tact with protesters and agitators who had started destroying property and looting stores.

“It has never been like this before,” another Oakland officer said of the constant stream of protests. “There is no breathing room.”

As officers have continued responding to protests — some of which involve trying to protect peaceful demonstrators while confronting agitators — experts say they become more prone to overreacting.

“The real concern is that tired people get grumpy and tend to make decisions more rashly,” said Dennis Kenney, a criminal justice professor at John Jay College. “Mistakes or aggression only compounds the problems in such circumstances.”

Officers say that many protesters are trying to provoke them into doing something wrong by yelling at them or even tossing full bottles of liquor at them that were looted from nearby stores.

“I think what’s unusual about this protest is that it is directly about police,” Berkeley police union President Chris Stines said. “There are people coming from all over the country that are upset with law enforcement in general.”

Because some of the protests have attracted hundreds of people including bands of anarchists seeking to destroy property, Whent said police must prepare for the worst even if it results in fatigued officers. “The cost of not overstaffing it is that the city gets destroyed in the process,” he said.

Whent praised his officers but acknowledged their frustration. “I don’t know the magic words that can really express the gratitude we have,” he said.

Contact Matthew Artz at 510-208-6435.