be frightened of (one's) (own) shadow
To be easily or constantly spooked, nervous, timid, afraid, or fearfully suspicious. I can't say I have much faith in Johnny helping us on this expedition—that boy's frightened of his own shadow! You can't live life being frightened of your shadow—you need to get out into the world and taste adventure! The basement really isn't scary. You can't listen to what Cara says, she's frightened of her own shadow.
Farlex Dictionary of Idioms. © 2024 Farlex, Inc, all rights reserved.