(CNN) The use of benzodiazepines, such as Xanax and Valium, is on the rise, and the number of overdose deaths related to them soared in recent years, new research says. Benzodiazepines are extremely popular drugs in the U.S. 
 
 Related: Drug Overdose Deaths Hit Alarming High 
 
 More than 5 percent of U.S. adults fill a benzodiazepine prescription every year, for conditions such as anxiety, mood disorders and insomnia. “But I think that epidemiologists need to pay closer attention to the role of benzodiazepines in overdose deaths.” 
 
 According to the Centers for Disease Control and Prevention, more than 22,000 people in the United States died of overdoses involving prescription drugs in 2013, the most recent year with available records. And, as the Einstein researchers showed, it’s not just the number of benzo prescriptions but the quantity filled in each script that has risen in recent years. "Going into this study, we thought that prescribing would be steady or decline in the late 2000s [because] people became more aware of opioids so there might be more attention" to benzodiazepines, said Dr. Marcus A. Bachhuber, assistant professor of medicine at Montefiore Medical Center and Albert Einstein College of Medicine. Bachhuber led the study, which was published in the American Journal of Public Health 
 
 But any hope that benzodiazepine prescriptions slowed was dashed as Bachhuber and his colleagues looked at national surveys of U.S. households taken between 1996 and 2013. Bachhuber’s team looked at large health surveys to find trends in their use and abuse. They found that the percentage of adults filling a benzo prescription increased by about 37 percent, from 4.1 percent to 5.6 percent, over the study period, while the overdose death rate shot up by more than 500 percent, from 0.58 per 100,000 adults at the turn of the millennium to about 3 per 100,000 throughout the early part of this decade. They found a similarly large increase in the number of pills each adult was prescribed. But in combination with other sedatives, often opioids and alcohol, "their lethality is magnified," Reisfield said.
– Opioids aren't the only drugs we should be concerned about when it comes to overdoses. ODs involving common anxiety drugs like Xanax and Valium are at an all-time high, and scientists fear plenty of lives will be lost before they fully understand why. In a new study, researchers found that prescriptions for benzodiazepines—used to treat anxiety, mood disorders, and insomnia in more than 5% of US adults—tripled from 1996 to 2013, while overdoses quadrupled, reports NBC News. In 2013, "benzos" played a role in 31% of the nation's 22,000 prescription overdose deaths, reports STAT. Seeing the rise in ODs outpace the rise in prescriptions suggests "people have been taking them in a riskier way over time," says lead author Marcus Bachhuber. One theory is that the spike in deaths is linked to higher doses—the amount of benzodiazepine in prescriptions doubled over the study period, notes CNN. It's also possible that people are taking them carelessly along with alcohol or opioids, in which case their "lethality is magnified," says a doctor not involved with the study. The death rate plateaued among white people, the largest users of benzos, between 2010 and 2013, but it rose among black and Hispanic people in that same span. The authors caution that benzodiazepines are being over-prescribed in general and suggest doctors should look into alternatives drugs or treatments such as talk therapy.