TITLE: Ways to help a math PhD out of depression
QUESTION [14 upvotes]: I have a friend who is having trouble in his math PhD career and is recently down with depression. He has decided to take a break from research and receive some medication. To help him recover faster and better, I am asking if anyone here with experience in helping depressed math PhDs could contribute his/her advice. Thanks in advance.
PS. If this question is more suitable on another stackexchange website, please feel free to move it there.

REPLY [22 votes]: I do have something to share. I would ask the following:
1) Is he getting well with his advisor?
2) Does he have a daily routine (i.e wake up at 8AM everyday, preparing for teaching, going to gym at 11AM, reading papers from 1PM, attending weekly seminar at 3PM, etc). This can be crucial to get someone out of the state of depression. 
3) Does he have potential plans after the PhD (with or without the degree)? 
If the answers are No, I would suggest taking some concrete steps now (switch to a new advisor, form a daily life routine, consider a Plan $B$ or even Plan $Z$ in case academia does not work for him). 
In case he still loves doing research, I would encourage him/her talk to some mathematican in industry but still actively doing research to have a better sense how to achieve this. If I recall correctly, Yakov Eliashberg, Vladmir Berkovich and 
Jeffrey Lagarias all worked at industry at some point, not to mention street names like Yitang Zhang.