The salty food was making her 'thirsty'.
a 'thirsty' child
(..) All right. Come on. Off to bed with you. (GRUNTS) - JANET: Night, Mom. - Good night, darling. Now, don't eat too many of those or you'll wake up thirsty in the middle of the night. All right? I won't. You promise? - Night, boys. - JOHNNY: Night, Mom. (..)2016 The Conjuring 2