It’s a myth we already discussed in our first book on myths about learning and education, but people keep dreaming of learning in our sleep.

This new study gives more insights about what is and isn’t possible: while the human brain is still able to perceive sounds during sleep, it is unable to group these sounds according to their organization in a sequence.

From the press release:

Hypnopedia, or the ability to learn during sleep, was popularized in the ’60s, with for example the dystopia Brave New World by Aldous Huxley, in which individuals are conditioned to their future tasks during sleep. This concept has been progressively abandoned due to a lack of reliable scientific evidence supporting in-sleep learning abilities.

Recently however, few studies showed that the acquisition of elementary associations such as stimulus-reflex response is possible during sleep, both in humans and in animals. Nevertheless, it is not clear if sleep allows for more sophisticated forms of learning.

A study published this August 6 in the journal Scientific Reportsby researchers from the ULB Neuroscience Institute (UNI) shows that while our brain is able to continue perceiving sounds during sleep like at wake, the ability to group these sounds according to their organization in a sequence is only present at wakefulness, and completely disappears during sleep.

Juliane Farthouat, while a Research Fellow of the FNRS under the direction of Philippe Peigneux, professor at the Faculty of Psychological Science and Education at Université libre de Bruxelles, ULB, used magnetoencephalography (MEG) to record the cerebral activity mirroring the statistical learning of series of sounds, both during slow wave sleep (a part of sleep during which brain activity is highly synchronized) and during wakefulness.

During sleep, participants were exposed to fast flows of pure sounds, either randomly organized or structured in such a way that the auditory stream could be statistically grouped into sets of 3 elements.

During sleep, brain MEG responses demonstrated preserved detection of isolated sounds, but no response reflecting statistical clustering.

During wakefulness, however, all participants presented brain MEG responses reflecting the grouping of sounds into sets of 3 elements.

The results of this study suggest intrinsic limitations in de novo learning during slow wave sleep, that might confine the sleeping brain’s learning capabilities to simple, elementary associations.

Abstract of the study:

Hypnopedia, or the capacity to learn during sleep, is debatable. De novo acquisition of reflex stimulus-response associations was shown possible both in man and animal. Whether sleep allows more sophisticated forms of learning remains unclear. We recorded during diurnal Non-Rapid Eye Movement (NREM) sleep auditory magnetoencephalographic (MEG) frequency-tagged responses mirroring ongoing statistical learning. While in NREM sleep, participants were exposed at non-awakenings thresholds to fast auditory streams of pure tones, either randomly organized or structured in such a way that the stream statistically segmented in sets of 3 elements (tritones). During NREM sleep, only tone-related frequency-tagged MEG responses were observed, evidencing successful perception of individual tones. No participant showed tritone-related frequency-tagged responses, suggesting lack of segmentation. In the ensuing wake period however, all participants exhibited robust tritone-related responses during exposure to statistical (but not random) streams. Our data suggest that associations embedded in statistical regularities remain undetected during NREM sleep, although implicitly learned during subsequent wakefulness. These results suggest intrinsic limitations in de novo learning during NREM sleep that might confine the NREM sleeping brain’s learning capabilities to simple, elementary associations. It remains to be ascertained whether it similarly applies to REM sleep.