In an interview with The New Yorker, Bright Eyes frontman/main songwriter Conor Oberst explained that he wanted the song to "sound like someone eavesdropping their neighbor, like, in the next door apartment." To capture this feeling the songs is recorded in an odd, muffled style, and uses ambient sound effects typical of what you'd hear in an apartment. Oberst was inspired by a Bjork song where the singer uses similar effects to create an atmosphere of walking in and out of a party.
The song uses piano and exaggerated, drone-y sound effects to create a uniquely dissociated atmosphere, while the lyrics are spare and suggestive. They're written from the perspective of a detached young woman who's trying to find a way to reconnect with the world and find meaning of it again. The song ends on a melancholy note, observing that "no matter what I would try and to in an attempt to replace the pills that balance my brain," the narrator will probably still remain the girl under glass - cut off from her true feelings.
Fevers and Mirrors was the third release by Bright Eyes, following their debut album and a subsequent EP. It was noted for Oberst's increased sophistication as a songwriter, as well as a focus on extremely dark, emotional, introspective lyrics. The title refers to self-reflection and brooding on your own perceived flaws.
The album was lambasted by the music review blog Pitchfork when it first released, earning a 5.4/10. However, the album ended up on as number 171 on the website's top 200 albums of the decade list, and its reissue received a 9.0.
Pitchfork's original review also commented on "When the Curious Girl Realizes She's Under Glass," noting that Oberst's vocals sounded "unnerving."