Not asking for help at work is your loss.

People would rather suffer in silence than ask a coworker for help on the job, according to a new study by the Harvard Business Review.

Researchers polled 238 employees in various industries to see if they would seek help from a coworker. They found five common reasons why workers avoid asking for assistance altogether: They prefer to be self-reliant and do their work on their own; they want to protect their image; they don’t want to have to return a favor; they don’t trust their coworkers’ motives; and they believe that their desk mates just aren’t as smart as they are.

In a separate but related Harvard Business Review survey, researchers asked more than 500 employees how much they agreed with the above reasons for not asking a colleague for help. Nearly two-thirds (66%) said they preferred to do their work on their own, and more than half agreed that this allowed them to be seen as “high potential” and hard-working employees. Almost 20% said they normally rejected assistance when others tried to help.

Mistrust among coworkers also appears to be discouraging teamwork. Nearly 10% of respondents said their coworkers didn’t have good intentions and were “out for themselves.” And about 8% of employees thought their coworkers were incapable of finishing the tasks.

The study also found that not asking for support when you need it can lead to serious mental fatigue and cause a greater risk of burnout. Those surveyed who were hesitant to accept help, even when they felt like they were “drowning in work,” were more likely to put in extra hours at the office to complete a project. But working more than 50 hours actually makes a worker less productive, according to a Stanford University study, which found that putting in 70 hours per week produces nothing more with those extra 15 hours.

If you’re afraid to come across as incompetent to colleagues, there’s a way to ask someone to lend a hand without looking like “I can’t do it.” Instead, initiate the collaboration by praising a colleague’s strengths and asking for her insight, rather than asking her to take over the task.

“Each individual has to recognize that we can ask our colleagues for ideas without suggesting that we are needy,” New York-based career coach Roy Cohen tells Moneyish. “It’s how we position the request. Say something like, ‘Hey, I’m working this project. I know that you’ll have some terrific ideas and a perspective that will be invaluable.’ Notice that I haven’t positioned it like, ‘I’m having trouble figuring it out.’ Instead it’s talking about the insight another colleague can offer.”

Cohen also suggests establishing yourself at the office as someone colleagues can go to to ask for help or advice on work; that way, when you need assistance, others will be more inclined to return the favor.

“Offer support often, that way it doesn’t come across as a one-sided professional relationship,” says Cohen. “If you’re helpful and supportive, others will feel a sense of responsibility to take initiative when you ask for their advice.”