The early bird does not get the worm: time-of-day effects on college students' basic cognitive processing

We conducted a neuropsychological and cognitive assessment study to determine whether time of day affects cognitive performance. We measured executive control (fluency), processing speed, semantic memory, and episodic memory performance. We followed 56 students across 3 different times of day, testing performance on vocabulary, fluency, processing speed, and episodic memory. Results showed an advantage for fluency and digit symbol task performance in the afternoon and evening testing times relative to morning testing (regardless of testing order), but that time of day did not affect semantic or episodic memory performance. These results suggest that optimal executive functioning and processing speed may occur for typical college students in the afternoon and evening regardless of time-of-day preference.