I was reading about the brain and sleep

You Sleep, But Your Brain Works

Dozens of intriguing studies over the past several years show clearly
that your brain is active-very active-during sleep.  It's busy doing something miraculous, something that we can't even come close to explaining.

Basically, your brain goes on automatic pilot. Without your being aware of it, something inside your head comes alive and starts mulling over all the things you learned that day. It sorts through them, organizes them, considers them, calculates them, decides what's important and what's not.

From all the information that your brain soaked up during the day, it derives meaning. It works through unsolved problems and somehow comes up with answers. Its powers, however, extend even farther than that. A spooky awareness speeds through neural circuits. As it does so, it changes the physical structure of brain cells so that specific pieces of knowledge are etched more permanently in memory. In the neurologic literature, these miraculous processes are referred to as consolidation.

What your brain is doing, without any conscious effort on your part, includse

organizing,

prioritizing,

problem solving, and

memorizing.

All this is happening while you sleep! As you can see, effortless sleep-learning is not only possible, it is a reality.

The amazing truth is that learning continues after the actual studying is done. In fact, research indicates the maximum benefit of all your hard hours of studying comes about only after a good night's sleep.

Furthermore, even though you may have stopped studying, knowledge and skills continue to improve over several nights of sleep.  Although sleep on the first night following training offers the most dramatic benefit, subsequent nights of sleep continue to provide smaller, less pronounced gains.