1
general::
Also, weigh upon. Depress, as in His criticism weighed on her, or The long silence began to weigh upon us. This idiom was first recorded in 1775.
American Heritage Idioms
2
general::
Phrase(s): weigh (up)on someone
Fig. to burden or worry someone. (Upon is formal and less commonly used than on.) • The problems at the office were beginning to weigh upon Mr. Franklin. • My problems began to weigh on me.
McGrawhill's American Idioms And Phrasal Verbs