Relationship between circadian typology and functional and dysfunctional impulsivity.

The present study explores the relationships between functional and dysfunctional impulsivity factors, circadian typology, and sex. A sample of 850 university students (396 men) aged between 18 and 33 yrs of age completed the Dickman's Impulsivity Inventory (DII) and reduced morningness-eveningness questionnaire (rMEQ). Factorial analysis showed a dimensional clustering with satisfactory item saturation for both dimensions of impulsivity, especially in men and evening-type. Men presented higher values than women for functional and dysfunctional impulsivity, while morning-type subjects obtained lower scores in dysfunctional impulsivity than the neither- and evening-types. An interactive effect between circadian typology and sex was obtained for dysfunctional impulsivity. Higher scores in men for dysfunctional impulsivity were found in neither- and evening-types, while no significant differences were obtained between men and women in the morning-type group. The morning-type typology can be considered a protective factor for impulse control disorders, especially in men, but further research is needed on the clinical and neurobiological implications of our results.