An unusual experiment suggests that interrupted REM sleep can interfere with the amygdala’s ability to process emotional memories overnight—in this case, the distressing memories of listening to oneself sing out of tune, reports The Scientist.

“Prior research has made clear the benefits of sleep—and REM sleep in particular—for the ability to regulate emotions,” notes Elizabeth Kensinger, a neuroscientist at Boston College who was not involved in the study, in an email. “But the present research goes farther in demonstrating—in humans—that there are variants of REM sleep that can be harmful to that ability to process emotions.”