That moment of dread and queasiness right before you log into your work email. (For severe cases, particularly on Mondays at 9:00 am, Uber Posten Angst.)
Sam, passing by Deb's desk: "What's wrong, Deb? You look kind of dazed and bummed out."
Deb, staring at computer screen and sighing: "Posten Angst. You know."
Sam: "Egh. Do I ever."