CLOCK and delirium: This is not surprising because delirium is usually reversible, and its duration is typically short lasting from a few days to weeks.[6] Impaired attention is another core feature of delirium according to DSM‐5 diagnostic criteria.[58] However, we did not explicitly assess the changes in the attention function in our delirium models, although inattention has been described in similar models.[59] It remains unaddressed whether and how the circadian clock regulates delirium‐associated attention impairment.