That feeling one gets on a Sunday when they know they have to go back to school and/or work the next day. Procrastination on a Sunday can also cause Sunday Depression, because doing work for school can make one depressed and get them into a "Damn it, I don't want to go to school tomorrow" feeling. People with Sunday Depression may have a frown on their face, get butterflies in their stomach, appear to be stressed or nervous, etc. This feeling does not normally occur when there is no school on Monday due to some kind of holiday.
Eddie: Hey man, what's wrong with you? You look down.
Vincent: I just don't want to go to class tomorrow and I still need to finish a paper for English.
Eddie: Sounds like you have a bad case of Sunday Depression.
-Urban Dictionary | 
