Netizens are showing strong concerns toward former Nine Muses member Sera, as they believe she is suffering from severe negative side effects of taking sleeping pills. 

Back on September 21, MBN's new girl group reboot reality program 'Miss Back' hosted by Baek Ji Young revealed a new teaser, focussed on former Nine Muses member Sera. 

In this teaser, Sera displayed strange behavior at night, by waking up in the early morning hours of the day, raiding her refrigerator and eating pizza, cake, etc. However, Sera revealed that she does not remember any of her strange actions when she wakes up the next morning. 

One netizen on an online community pointed out that this type of behavior was highlighted in the past on an episode of 'Unanswered Questions'. 

The behavior was coined as a negative side effect of the insomnia medication zolpidem, which was prescribed to patients receiving treatment and therapy for depression and similar mental illnesses. 

Sure enough, according to Sera's 'Miss Back' teaser, the show will be dealing with her battle with mental illness once it begins airing. 

Many concerned netizens commented, "This is so sad, Sera was my favorite Nine Muses member TT", "It's a really scary side effect of that medication", "Yeah I remember that episode of 'Unanswered Questions', there were people who woke up in the middle of the night and ordered delivery but forgot about it the next day, and people who called family over the phone but didn't remember the next day", "What happened to such a talented girl TT", "I hope she can quit those pills and get better soon", "I've been watching her YouTube videos but I had no idea she was this sick TT", "This is so sad, Star Empire I hope you're happy TT", and more. 

Meanwhile, MBN's 'Miss Back' starring Nine Muses's Sera, and more is set to premiere on October 8.