The concept of sleep learning, or hypnopedia, has a long history. In 1914, Rosa Heine found that learning new material in the evening before sleep results in better recall compared to learning during the day. Thanks to many studies done since then, we now know that sleep is crucial for forming long-term memories of what we have encountered during the day. The type of learning that happens during sleep tends to involve pairing, conditioning, and associations. Therefore, sleep learning can be useful to improve our languages skills, or to better remember music and melodies.
