Everyone I know of that has played the game Tetris, also have had Tetris Dreams. Even though you're asleep, you just keep on stacking those blocks on top of each other, making entire rows disappear. I very seldom play the game, but I have learned to use it as a sleeping pill; instead of counting sheep, I play Tetris in my head. And now, Scientific American reports of a study made by Robert Stickgold that uses Tetris Dreams to confirm the idea that the brain uses dreaming to reinforce learning. It turns out that 60% of the participants in the test group reported Tetris Dreams. 

There were several interesting results from this study, which does confirm old and reveal new knowledge about how the brain learns. For instance, Tetris Dreams were more frequent after the second night after playing the game than after the first. This implies that the brain really wants to be sure that it will have to learn this crazy new thing. Also, people who were Tetris novices reported the most dreams, and they were also more likely to see Tetris images during sleep onset, because their brain felt it needed more time with this than the expert players did. Furthermore, a group of amnesiacs were included in the group and though they were Tetris novices and had no memory of having played the game the day before, they still placed the fingers in the correct playing position before the game started !

Your brain will remember things you don't.

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