And it could be causing serious side-effects. 
Woman working with men
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As if we needed another reason to send more women to level-out STEM fields, now we have it. New research from Indiana University Bloomington shows that the interpersonal-stress from working in a male-dominated field like engineering and construction can be as bad for women’s health as living in poverty.

For the study, presented at the 2015 American Sociological Association Annual Meeting, researchers used data from the 2004 to 2009 MIDUS II Daily Stress Project. The project collected participants' cortisol (a stress hormone) samples while walking, 30-minutes after walking, during lunchtime, and before going to bed. They controlled for sleep, medications, medical conditions, and health indicators that might skew cortisol levels, such as too little sleep, or whether the participant was a smoker, took cortisone supplements, or suffered from depression or anxiety, among other controls. They also used the American Community Survey, which tabulated occupational sex distribution from 2005 to 2009 to focus on occupations with sex tokenism—where females make up less than 15 percent of the total number of employees.

After a statistical analysis, the researchers found that "token" women had less healthy cortisol profiles than the women who worked in mixed sex occupations, and that the dysregulation was stable and chronic, not a reaction to daily stressors. “The dysregulation of cortisol profiles we observe is due to the negative working conditions of token women, and not their own personal characteristics nor the characteristics of their occupations,” lead researcher Bianca Manago said in a statement.

According to previous research, a healthy cortisol pattern peaks right after waking and then falls through the day—first rapidly and then more gradually, eventually reaching an absolute low-level near midnight. However, research suggests stress, temperature, conflict, and immune responses can all affect the cycle and raise cortisol patterns. Though cortisol levels usually self regulate, chronic stressors can dysregulate the daily cycle—something that has been linked to health problems such as chronic fatigue, fibromyalgia and post-traumatic stress disorder.