Gamers: Dream Your Way to a Better Score describes the results of some experiments suggesting that dreaming is part of the learning experience, where researchers used DOOM to measure this effect.

On the second night, nearly everyone dreamed about Doom and about half dreamed about the laboratory. However, when the researchers compared players' performance before and after sleeping, only Doom-related dreaming was correlated with improvement at the game.

The researchers scored performance by analysing video recordings of the game and noting the number of player deaths, enemies killed, secret passages discovered, shooting accuracy and five other measures.

They found that the more Doom-dreaming a player did, the more likely he or she was to improve on these measures – but only up to a point. Volunteers who dreamed most about Doom didn't see the biggest gains.