If the apps are to be believed, you can learn to find love or brush up your golf skills while sleeping. Neuroscientist Jordan Gaines Lewis explains the facts behind the fiction in The Guardian.

A study published last year by Swiss researchers suggested that sleep enhances our ability to learn foreign language words. Subjects were presented with a series of Dutch-to-German word pairs at 10 pm, then listened to an audio recording of these word pairs until 2 am. Half of the group, however, was allowed to sleep during this period. When re-assessed, the researchers found that those who slept recalled significantly more words than those who didn’t.