How To (Really) Learn Spanish Language While You Sleep

The old saying that we can solve problems more effectively when we “sleep on it” may be especially true if the problem we’re trying to solve is learning a new language.

Researchers from two Swiss universities wanted to know if they could enhance the learning of words from a foreign language by exposing people to the words during non-rapid eye movement sleep (NonREM sleep) – the deep, dreamless sleep period that most of us experience during the first few hours of the night.

To find out, they gathered two groups of study participants, all of whom were native German speakers, and gave them a series of Dutch-to-German word pairs to learn at 10 pm. One group was then instructed to get some sleep, while the other group was kept awake. For the next few hours both groups listened to an audio playback of the word pairs they’d already been exposed to and some they hadn’t yet heard.

The researchers then re-gathered both groups at 2 am and gave them a test of the Dutch words to uncover any differences in learning.

And indeed there was a difference: the group that listened to the words during NonREM sleep did significantly better at recalling the words they’d heard at 10pm.

The simple yet potent trick the researchers employed is known as “verbal cueing,” and this isn’t the first claim made for its success while sleeping. But what makes this study different is that it puts a finer point on the conditions necessary for this trick to actually work—namely, it only works when we’ve already been exposed to the verbal cues before we sleep.

The researchers added a techie dimension by conducting electroencephalographic (EEG) recordings of the sleeping participants’ brains to track neural electrical activity during the learning period. They found that learning the foreign words overlapped with the appearance of theta brain waves, an intriguing result since theta is the brain wave state often associated with heightened learning while awake (usually we’re in either the high-frequency, high-alertness alpha or beta states while awake, but it’s thought possible to induce theta state—slower in frequency than alpha and beta—through concentration techniques).

So, to make practical use of these findings you’ll need to make sure of two conditions: only play audio of foreign words you’ve already heard, and set the audio to run for the first two to three hours of sleep. When you wake, give yourself a quiz to test your recall.  Do that for a few weeks before going on the big overseas vacation, and you’ll likely find yourself communicating more fluently with the locals.

The study was published in the journal Cerebral Cortex.