Owl or lark? Stroop-related cerebral activity is modulated by time of day and chronotype

Methods: Thirty extreme chronotypes (16 early (ETs), 14 late types (LTs)) underwent 2 fMRI sessions, 1.5 and 10.5 hours after preferred waking up controlled throughout actimetry the week prior testing. Circadian phase was asserted by saliva melatonin samples. Polysomnography was recorded the nights preceding test sessions. During fMRI scanning, subjects performed a Stroop conflict paradigm where subjects must name the printed colour of a colour name, with congruent (C), incongruent (I) and neutral (N) trials. Results are reported at the group level, p<0.001.