I went to see the doctor recently due to some of the following symptoms. This was my diagnosis.
Symptoms: extreme fatigue, lethargy, & complete lack of motivation to do anything, often coupled with extreme opposite symptoms of mania, hyper-activity, and motivation to do everything.
Possible Cause: The body's reaction to being in fight or flight mode for the years of being in a PhD program pursuing those 3 letters after your name.
Prognosis: development into a more extreme syndrome likely, such as:
*Also possible: I-can-do-all-the-things syndrome