We all hear the stories about people who learn new languages from scratch just by listening while sleeping. Hypnopedia, or the ability to learn during sleep, was once a popular belief, but Belgian scientists are happy to bust that myth.

A study conducted by the ULB Neuroscience Institute in Brussels and published in Scientific Reports shows that the brain continues to perceive voices while sleeping just like it is awake but cannot sort these voices.

The science team, led by Philippe Peigneux, put subjects to a series of tests to see whether hypnopedia is the real deal.

At first participants were exposed to fast flows of pure sounds while sleeping, either randomly organized or structured. During sleep, brain magnetoencephalography (MEG) responses demonstrated a preserved detection of isolated sounds, but no response reflecting statistical clustering.

During wakefulness, however, all participants presented brain MEG responses showing that the participants' brain can sort the voices and group them in ways that give meaning to them.

In short, the brain is still active enough to learn elementary subjects, but complex subjects, such as a new language, do not seem possible.