A new theory may explain why a learning strategy I’ve been promoting to students for years actually works.

The learning strategy? Sleep on it.

I teach a course at Colorado State University called Science of Learning. It is intended to instill in students study skills and habits that are grounded in science. As you might expect, we cover many strategies for remembering information. We also cover strategies for improving skilled performance in various domains such as sports or music or dance. But another important piece of what we cover concerns understanding and .

Understanding and innovation are tricky. No one can predict the precise moment that something will click for any given student, or when a novel creative insight will take place.

Though creative insights can happen suddenly in the form of Eureka moments, these moments don't happen randomly. They usually happen after lots of time and effort spent thinking about (and on) the problem or issue. As Steven Johnson argues in his TED-Ed presentation, "ideas need time to incubate."

Importantly, there are things that you can do to improve your trajectory toward arriving at a moment of creative insight, understanding, or breakthrough. In their book, "The Eureka Factor: Aha Moments, Creative Insight, and the Brain," John Kounios and Mark Beeman describe many such factors. Among the ones I teach in my Science of Learning course are:

Space out your attempts at thinking about the problem or issue

When in a rut, take a break

Get episodes of sleep in between attempts

Note this last one. Sleep in between attempts.

Researchers have long known that sleep helps memory and learning. In fact, I tell students that sleeping in between attempts at learning is one of the most powerful yet underestimated strategies for enhancing learning. The reason has to do with the consolidation processes occurring in the brain during sleep. Memories get solidified and strengthened during sleep (primarily during Slow Wave Sleep). This process likely contributes to why spacing out one’s studying across days is more effective than cramming studying into one day (this relates to the first bullet above). When you space out your studying, then each day, you are building upon already-consolidated knowledge and memories.

But why should sleep enhance understanding, innovation or creativity?

The fact that it does has been known for awhile. (This is why I promote it). For example, in their 2004 Nature article, Sleep Inspires Insight, Wagner and colleagues demonstrated that when people slept after initially being trained on problem sets that had a hidden structure to them, they were about twice as likely to discover the hidden structure than if they didn’t sleep afterward.

We are now closer to understanding why. In their new article, How Memory Replay in Sleep Boosts Creative Problem-Solving, Penelope Lewis and colleagues present a possible mechanism.

Whereas researchers have known for some time that the phase of sleep known as Slow Wave Sleep (SWS) is largely responsible for the strengthening of memories and abstraction of gist, Random Eye Movement (REM) sleep, which is the phase when occur, has been less well understood. Lewis and colleagues suggest that mutual interaction between the SWS and REM phases across sleep cycles may underlie sleep's promotion of creative insight. They propose that the SWS phase works to abstract the gist from recent experiences, building one's general knowledge-base. Then, the REM phase works to spontaneously replay various memories from the cortex. Think about the seemingly random connections from your past that occur in dreams that you remember.

They may not actually be random.

Lewis and colleagues argue that the knowledge-formation that takes place during SWS actually biases the brain to activate distantly relevant memories from the cortex for replay during REM sleep. In other words, the brain may detect very subtle connections between older memories and the newly formed knowledge that occurred in the latest SWS phase, and select these subtly-related older memories for replay during REM sleep.

In cyclical fashion, this replay during REM sleep biases the next SWS phase toward abstracting the gist from these newly dreamt experiences, helping to strengthen the newly-detected connections in the knowledge-building abstraction phase. And so on. After many iterations throughout a night's sleep, the mind is primed to make a mental leap when awake. This may be why sleep is so conducive to innovations or insights.

Of course, innovation won't just happen overnight. Remember: Ideas need time to incubate. This is why spacing out your attempts (and getting episodes of sleep in between) is so important.

But if it ever seems like an insight came to you from a dream, it very well may have.