Life as a tired resident

These days I'm feeling so tired and have this general feeling similar to mild despair and sadness during the day.  I don't know really remember when my last day off was and I've been trying to get through each day an hour at a time.  A lot of my friends in residency make comments about how they're also feeling stressed and worn out.  I don't really laugh at jokes anymore at work and have been feeling more irritable.  I can't wait to get some rest