That is what grief does to our brain. It is wired for ‘fight, flight or freeze’ and ‘rest and digest’. Grief is the brain’s freeze response to a perceived threat that is so devastating that it doesn’t know what to do to protect us. So we slow down, take to our couch, maybe barely eat and certainly curtail most activity. We experience brain fog and fatigue. It may take a few days to slowly come back to life. If it takes many weeks or months some professional medical assistance is likely warranted. However long it takes we want to see a progression from intense fatigue to restoring an active life.