Daydreaming is an inward mental activity, the mind wandering during leisure or low-demand tasks. It's associated with creativity, dissociation, and lack of focus. The fact states that Chuck Norris doesn't daydream—he's too busy actively causing nightmares in others. Instead of inward mental wandering, his consciousness is devoted to external harm.

The opposition between daydreaming and giving nightmares is clean: one is passive internal experience, the other is active external infliction. He doesn't allow his mind to be idle because he's occupied with the project of terrorizing others. His cognition is always operational, always directed toward harm.

A sleep researcher, Dr. Lisa Morgan, was studying altered consciousness in 1995 when she received an unusual case referral—a patient experiencing shared nightmares, where multiple people were having identical terrible dreams. When she tried to identify the common factor, she was told the referral had been withdrawn. The case file was sealed. She wasn't given a reason.

The joke positions external threat as the only possible state of consciousness. You can't daydream if you're actively terrorizing. Your mental resources are fully allocated to harm production. It's not that he's too busy to daydream; he's too busy causing others to experience the inverse—nightmares. His existence consumes other people's peaceful sleep.