Meaning of the word "have something on the brain" in English

What does "have something on the brain" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

have something on the brain

US /hæv ˈsʌmθɪŋ ɑn ðə breɪn/
UK /hæv ˈsʌmθɪŋ ɒn ðə breɪn/
"have something on the brain" picture

Idiom

to be unable to stop thinking or talking about something

Example:
He's been having something on the brain about his new project all week.
Ever since she got the promotion, she's had nothing but work on the brain.