Sci-fi writers, neuroscientists, conmen, and ambitious overachievers have all been attracted to the possibility of hypnopedia, the capacity to learn during sleep. But a new study published in Nature Monday shows that the brain's sense-making capabilities are severely limited while in slumber and the potential for the retention of high level information is almost non-existent. In other words, sleep thankfully remains a place we can escape to without feeling like we have to be doing something else productive.

Researchers at the ULB Neuroscience Institute in Belgium recorded cerebral activity in humans as they were being played a series of sounds, both during sleep and wakefulness. They found that although the sleeping brain can perceive discrete noises, it cannot organize these inputs into coherent sequences like we do when we’re awake.

The concept of hypnopedia emerged in the late nineteenth century after the phonograph was invented. One of the earliest attempts at sleep-learning came in the early 1930s, when Alois Benjamin Saliger’s patented his “Psycho-Phone,” an Edison-style phonograph with an attached timer, which delivered messages like “I radiate love” or “I have a fascinating and attractive personality” to people as they slept. Saliger said that these messages could insert themselves into the unconscious and subsequently have a profound influence on waking behavior.

Saliger’s claims were debunked in the 1950s when scientists started recording brain waves accurately via electroencephalography. They concluded that learning during sleep was impractical, if not impossible, after which hypnopedia was more or less abandoned as a field of research (though it remained popular within New Age subcultures.)

In the past decade, however, several studies have suggested that certain types of memories can be consolidated during sleep by exposing the brain to outside stimuli like noise and smell. This most recent study, however, demonstrates an “intrinsic limitation” on the possibilities of hypnopedia.