Two different studies conducted by University of Illinois at Chicago researchers found that rude emails can cause significant employee distress. The results, published in August in the Journal of Occupational Health Psychology, show the ways in which bad email behavior can increase stress, decrease workplace productivity, and yes, even keep you up at night. The first study included 233 workers, who were surveyed about their experiences with “impolite emails.” The second study had the subjects keep a journal of their reactions to these emails, including their ability to fall asleep and stay asleep. There are two different kinds of rude emails, the researchers explain. “Active email rudeness” is pretty self-explanatory, and if you’ve ever sent or received a hostile message, you’re very familiar with the concept. “Passive email rudeness” can be as simple as ignoring a question or request in an email, or not writing back at all. This “makes it difficult to know whether the receiver simply forgot to answer the email or actually intended to ignore it,” a write-up of the study notes.ae0fcc31ae342fd3a1346ebb1f342fcb The latter may seem like less of a problem, but it’s very common—think of how many times you’ve forgotten to respond to a coworker’s email versus how many times you’ve sent a profanity-laden missive. The lack of reply can create a feeling of uncertainty, which causes stress. “Because emails are securely stored, people may have a tendency to revisit a disturbing email or constantly check for a response that they requested, which may only aggravate the distress of email rudeness,” lead study author Zhenyu Yuan, PhD, assistant professor of managerial studies in the College of Business Administration, said in a statement. “Active e-mail incivility leads to a greater level of emotionality appraisal,” the study says, but passive email rudeness is where sleep disturbances come into play. In the second journal-based study, researchers concluded that these emails that went unanswered were “positively associated with insomnia, which then leads to heightened negative affect at the beginning of the workday.” That means that if you’re sending emails that don’t get a response, it could literally be keeping you up at night. RELATED: For more up-to-date information, sign up for our daily newsletter. The goal for workers is to “psychologically detach” from rude emails, according to researchers. That means unplugging after a long day at work, and ideally not going back to those emails on your phone—whether they’re aggressive or simply ambiguous. There are real consequences to email rudeness, but the answer is not more email, Yuan stresses. “It should be noted that efforts to address email rudeness should not be interpreted as the same as creating pressure for employees and managers to always check their email and respond to emails,” he said. “On the contrary, setting clear and reasonable communications norms can prove effective in addressing both.” And if you’re struggling to hit the hay, try Writing This One Thing Down at Night to Help You Sleep.