In ancient Greek, kairos signifies the opportune or critical moment. Kairos captures a qualitative, rather than quantitative, aspect of time: expressing the rightness of timing, the critical instant when circumstance and action converge. The KAIROS project investigates the neural mechanisms underlying time processing within the cerebellar clock, with emphasis on time perception variability in ADHD. The aim is to elucidate the fundamental architecture of our internal timing system, to understand human temporal cognition.