Research > Topics > Relationship between the level of cognitive performance, mood and the electrophysiological sleep variables (2003 – 2005, Hungarian Medical Research Council: ETT-162/2003)

Our scientific aim was to unravel the procedures and theoretically based correlations, which make us able to gather information on cognitive and affective characteristics of human subjects based on the analysis of their sleep states. Do to the fact that most current electroencephalographic analysis methods are unifying in nature and are characterized by insensitivity to interindividual differences; we faced the problem of inadequacy of these methods in following our scientific aims. As a consequence we developed new analysis procedures [1, 2]. Using these procedures we unravelled several relationships between sleep and cognition. Both the density as well as the grouping by the slow oscillation of frontally registered fast sleep spindles correlated positively with intelligence [1]. However, the relative amplitude spectra of slow spindles occurring over the frontal regions correlated negatively with intelligence [2]. Visuospatial memory performance was positively related to right parietal fast sleep spindle density, but correlated negatively with the relative amplitude spectra of slow spindles, the latter relationship being a region-independent one [3]. Digit span was a part of verbal memory testing procedure and its result correlated positively with the left/right asymmetry of fast sleep spindles (left sided fast sleep spindle dominance). In contrary to our previous result, we did not find a relationship between cognitive performance and the slow oscillation, which means that this hypothesis was not supported. However, the quantification of the slow oscillation provides useful information in the characterization of the cognitive deficits inherent to some neuropsychiatric disorders [4]. At the same time the quality and quantity of night time sleep has a prominent role in the regulation of mood as well as affective state-related health of humans, however the deeper investigation of this topic calls for studies aiming to reveal the relationship between sleep and personality [5].