I have just finished up my 12 day sober, and for the past three days, I have been extremely tired. I figured it is part of the detox cycle and repair occurs during sleep. After all the years I have drank, I have a lot of body repair to do. Get your rest, but don't forget to have some movement as well. Listen to your body, and as others have said, if the fatigue points to a depression, see your Dr.