Sleep and intelligence  are linked, at least by some factors. There is a special aptitude – consisting of intelligence, intuition and fantasy – which is fostered by the REM sleep, i.e. when we dream; this aptitude is creativity. Some researchers  believe that this stage gives a boost  to the ability to find creative solutions to the problems.  The research highlighted that – in a test that was calling for the creative combination of elements and information – those who had slept with the presence of the REM phase proved to be 'brighter' than those who had simply rested on taken a nap without entering the REM phase. Not only memory, therefore: sleep also helps  lateral thinking, in particular when you reach the REM phase. During this stage, the external stimulations are confined outside the consciousness, this is a symbolic moment of introspection and relationship with oneself. In this very conditions of extreme closure to the outside and opening towards the internal stimulations and feelings, the mind manages to nourish and let its own creative abilities grow. After all, we say 'I will sleep on it' and we do know that he most crucial answers are found when you look into yourself. In front of an issue – then – instead of 'racking your brains' it might be useful to close your eyes and have some good sleep.