Recently I was asked by a friend’s son if it were possible to learn while asleep. He had read about sleep helping with memory and wondered if he could tape some of his lectures and listen to them while asleep. I told him that is an interesting idea but that it does not work. However, as I explained to him, sleep does serve to improve our memories. We just can’t learn new information being presented while asleep.
There are three broad types of memories: Declarative memory, which can be expressed verbally; Procedural memory such as learning to ride a bike, drive a car, or play an instrument; and Emotional memory.
There are two main types of sleep: REM or dream sleep and Non-REM sleep which comprises the other stages of sleep including the most important, deep or delta sleep. They come on in cycles every 90 minutes. The Non-REM deep sleep prevails in the first half of the night, and REM sleep dominates during the second half of the night. Non-REM sleep is more important for absorbing declarative memory (factual) and REM sleep is essential in procedural and emotional memory.
During the process of memory consolidation, your brain uploads short term unstable packets of information plus experiences and then converts them to more stable and longer lasting memories. It also integrates them with prior memories. This process has been linked to the stages of sleep.
Accordingly, besides insuring that we get a good night’s sleep, is there anything else we can do to improve our memory? Several studies paired learning before sleep with either sounds or odors. When the subjects were re-exposed to these sounds or odors while asleep and during specific stages of sleep, they showed a significant improvement in memory retention when tested.
Other studies have shown that increasing deep sleep with the aid of a very low frequency direct current improved memory retention the following day. However, all of this is experimental and I would caution the reader to be skeptical of gadgets worn to bed that are claiming to improve your memory. The good news is that we are realizing the importance of sleep with regard to memory and I believe it won’t be long before we have the ability to improve memory.