Watching a marathon of The Walking Dead could turn you into a zombie, too.

Binge watching your favorite shows may be detrimental to your sleep, according to the University of Michigan and Leuven School for Mass Communication Research in Belgium.

“Our study signals that binge viewing is prevalent in young adults and that it may be harmful to their sleep,” said co-author Jan Van den Bulck, a professor at the University of Michigan.

Previous studies have shown that binge-watching is a common pastime. Indeed, consulting firm Deloitte published data earlier this year indicating that 90 percent of millennials have confessed to binge-watching, taking in “an average of six episodes, or five hours of content,” in one sitting. What’s more, in 2015, watching streamed content consumed 42.5 billion hours of Americans’ valuable time, according to Time Magazine.

Participants in the study got an average of seven hours and 37 minutes of sleep per night, but it was the quality of sleep that separated those who binge-watched from those who didn’t. Binge-watchers more frequently experienced diminished sleep quality and felt fatigued.

So, how does binge-watching take a toll on our Z’s? Researchers uncovered a link between bingeing on shows that get your heart beating faster and absorb your concentration, and increased “cognitive arousal,” or stimulation in the brain. Heightened brain activity translates to more trouble switching off at bedtime.

This “prolongs sleep onset or, in other words, requires a longer period to ‘cool down’ before going to sleep, thus affecting sleep overall,” the study’s lead author Liese Exelmans explained.

But it’s not just staying awake and mentally replaying a show’s most stressful scenes that impedes sleep quality. Some binge-watchers put off sleep altogether, opting instead to stay awake watching till all hours of the night before finally hitting the sack.

Lauren Pizzio, 32, of Pompano Beach, Florida, is one of these viewers. Pizzio admits that she has fought off exhaustion to sneak in a few more episodes of her favorite shows, like Showtime’s Shameless, in the past.

“I usually go to bed early, but watching Shameless would have me up till 2 or 3 A.M.,” Pizzio told Moneyish. “I literally binge-watched from the first season to the last.”

And, “on a weekend, I could go six hours or even seven,” Pizzio added.

The repercussions of sleep deprivation are well-documented: impaired memory function, reduced alertness, and susceptibility to being in a bad mood, according to Cleveland Clinic.

In addition, lack of sleep can interfere with your love life, says psychologist Theresa DiDonato. “Sleep deprivation can make you less attractive,” DiDonato wrote in Psychology Today, adding that previous research conducted in Sweden concluded that people who didn’t sleep enough “were judged as less attractive and less healthy.”

Plus, “people who sleep poorly tend to display more negative emotions and are less successful at conflict resolution,” she added, warning that lack of sleep can lead to more severe disagreements between partners.

Even so, shows like House of Cards and Orange is the New Black are irresistible binge material for many streaming subscribers, who can power through entire seasons in a single weekend. Netflix alone now claims over 103 million viewers, and Amazon Prime isn’t far behind with at least 85 million.

And, those who subscribe to multiple services may be paying with more than just their sleep: Subscribing to even the most basic Netflix, Hulu, and Amazon Prime plans could cost you almost $300 a year.