FORTUNE — The boss doesn’t understand how tough this project is going to be. These deadlines are totally unrealistic. This customer is getting on my last nerve. What, we’re supposed to work late again? Those idiots in IT (or HR, or fill in the blank) have really screwed up this time. Why can’t anybody around here follow through on a simple request?
If the background buzz in your office sounds something like this, you’ve got plenty of company. About 70% of Americans say they work with someone who’s always griping, according to a new poll of 1,060 employed adults by WiFi advertising network Cloud Nine Media. Of that group, 67% admit that being around nonstop complainers sometimes puts a damper on their own productivity.
And no wonder. Recent advances in neuroscience have turned up some intriguing insights into how a steady barrage of negative thoughts can affect the human brain. Researchers have long known that our gray matter is surprisingly plastic and is quick to begin forming new patterns. Strengthening synaptic connections through repetition, for instance, builds the capacity to recall and retain information.
MORE: “Rogue IT” is about to wreak havoc at work
Now, studies using MRIs and other tools have taken that one step further. “Negative words stimulate the areas of the brain associated with perceptions and cognitive functioning,” notes serial entrepreneur and career coach Trevor Blake. “It’s clear that constant exposure to complaints will reinforce negative thinking, and your behavior is likely to change to fit those negative perceptions.”
Consider one of the recent studies Blake cites in his new book, Three Simple Steps: A Map to Success in Business and Life. Robert Sapolsky, a professor of neurology and neuroendocrinology at Stanford University’s School of Medicine, has done extensive research on the effect of stress on the hippocampus, which makes connections among other parts of the brain, and is also one of the few regions able to produce new neurons.
Unfortunately, the hippocampus is also highly sensitive to negative stimuli. Sapolsky found that exposure to a stressor — such as listening to someone spread a nasty rumor at work — for more than 30 minutes leads to elevated cortisol levels that hamper synaptic connections and speed up cell death. Over time, Blake writes, repeated bouts of negativity will cause the hippocampus to shrink, resulting in “declines in cognitive function, including the ability to retain information and adapt to new situations.”
Who needs that? Luckily, the brain can also be trained to form positive patterns, instead of merely reacting to stressors. Blake offers these 4 tips for minimizing negativity:
1. Self-awareness. Complaining can be contagious, so if you find yourself falling into the same mental habits as the malcontents around you, stop yourself. “When a negative thought pops into your mind, immediately revise it. Instead of telling yourself, ‘That’s a nice shirt, but I can’t afford it,’ change the message to, ‘That will look great with my black pants when I can afford it,’” Blake says. By doing this, you’re fostering “the process of neurogenesis — creating and reinforcing pathways in your brain that lead to positive behaviors.”
MORE: Why many entrepreneurs come across as jerks
Of course, he adds, everyone complains sometimes: “Your favorite team loses. Your computer crashes. Deadlines pile up. It’s human to vent now and then. But the less frequently you complain, the more time will pass between lapses into negativity. This is how rewiring the brain works.”
2. Distance yourself. Whenever possible, Blake advises, escape from negative conversations. “Excuse yourself and go somewhere quiet, ideally somewhere outdoors in the fresh air,” he suggests. “Think of something pleasant before returning. You have to take this seriously, because negative people can and will pull you into the quicksand.”
3. Don’t try to convert complainers. “If you find yourself trapped in a toxic group of complainers in a meeting or at a social event, simply choose silence,” says Blake. “Let their words bounce off you while you think of something else.”
Attempting to stop the griping may just alienate the group and make you a target, he adds, but you can redirect the discussion in your own mind: “If someone says, ‘I hate Mondays, weekends are too short,’ try countering that by thinking, ‘I’m glad I rested up over the weekend, so I’m ready to make some headway on that big project’” — or whatever positive thoughts you can conjure up to keep you from getting mentally mired in someone else’s whining.
MORE: How to create a mobile-friendly workplace
4. Transfer responsibility. “On occasions when you’re pressed against the wall while someone is ranting, throw the responsibility back at them by calmly asking, ‘So what do you intend to do about it?,’” Blake suggests. “In most cases, complainers don’t really want a solution, nor are they looking for sympathy. They just want to vent, and this tactic will stop them in their tracks.”
Who knows, expecting the chronically disgruntled to come up with actual fixes for their (real or perceived) problems may inspire them to leave you alone and find someone else to complain to. If so, your hippocampus will thank you.
Talkback: Have you ever worked with a constant complainer? Do you work with one now? What did you do about it? Leave a comment below.