Sleep dependent brain electric activity as a reliable indicator of the individual brain functional neuroanatomy has been proved to have high internight reliability, consequently representing an ingenious instrument for revealing individual differences. The focus of our scientific interest is the research of sleep related brain electric activity correlates of aging, general and specific cognitive abilities, personality and of trait-like affective styles, including attachment. We endeavour to exploit the broad opportunities offered by the latest quantitative EEG analysis methods to reveal the hitherto hidden aspects of the central neural activity in function of age, cognition, personality and mental health. We also plan to correlate these data with volumetric Magnetic Resonance Imaging assessed brain morphology. Besides significantly enriching our factual knowledge of the composite relationship between brain function, structure and behaviour, this approach also hides expectedly multiple possibilities for developing new diagnostic tools in different psychiatric disease.