Is sleep learning possible? The answer is yes and no, depending on what we mean by "learning."
Absorbing complex information or picking up a new skill from scratch by, say, listening to an audio recording during sleep is almost certainly impossible. But research shows that the sleeping brain is far from idle and that some forms of learning can happen.
The first study to demonstrate a memory and learning benefit from sleep was published in 1914 by German psychologist Rosa Heine. She found that learning new material in the evening before sleep results in better recall compared to learning during the day.
In recent years, multiple studies have found that a basic form of learning, called conditioning, can happen during sleep. In a 2012 study published in the journal Nature Neuroscience, Israeli researchers found that people can learn to associate sounds with odors during sleep.
Although the memory was implicit, it could affect the people’s behavior, researchers found in a 2014 study published in the Journal of Neuroscience.
sleeping：名詞，睡眠；形容詞，睡著的。例句：There are only 24 hours in a day, and usually about a third of that is spent sleeping.（一天只有24小時，通常3分之1是用在睡眠。）
learning：名詞，學習。例句：Sleep learning could be useful when people need to change a habit or alter stubborn disturbing memories.（當人們需要改變習慣或克服難以駕馭的煩擾記憶時，睡眠學習法能有所助益。）
memory：名詞，記憶。例句：Sleep benefits the retention of memory.（睡覺有助於鞏固記憶。）