Effects of financial burden on PhD research I am currently finishing up my 3rd semester in a very good (top 10-15 in US) PhD program in math. After this summer, I will have passed all my quals and will seriously have to think about my research. But I have been plagued with financial problems for the last two years and it is currently causing me following problems: 


I work multiple part-time jobs outside of class and TA-ship, just to break even with my financial obligations. The fact that I am an international student makes it even harder to find such jobs; I usually end up working for late night jobs for low pay. 
Getting tired from work, I rely on caffeiniated drinks to basically just survive and do my class works. It seems like forever since the last time I felt fresh and full of enthusiasm to do math. Going to seminars, attending reading groups etc all impossible because of it.I guess it has been working so far only because I am only in my 2nd year and only taking classes. 


So my question is that how realistic it is for me to continue like this and expect to be at least moderately successful doing research? If there is anybody here who dealt with similar issues, I would be very glad to hear what your solution was. 

P.S: Quitting the program and going back to my home country is not option an - I will have to stay in the program until I finish it or get a full-time, industry job in US, whichever comes first. Also, my adviser is sympathetic with my situation and helped me a lot by securing me a summer position, but that is the extent of what he can do to help me financially.
I had an almost identical situation. Due to financial commitments and the lack of grant, scholarship etc availability - I had to do close to fulltime work while completing my PhD (experimental physics).

I can assure you that I got through it, it was exhausting but very much worth it.

What I did:


As you are doing, keeping the advisor in the loop, informing them of what is required for work (time, energy etc), but at the same time, discussing and setting short and medium term goals.
Set yourself weekly goals, make these achievable and unambiguous.
Give yourself some evenings off to rest, and occasionally a weekend (I did this every 5 weeks).
Keep the sleeping, meal and exercise patterns - can not emphasise how important this is.


and possibly a weird one (but it worked):


keep a notepad or a small printed copy of a task in your pocket.


But, still seek the possibilities for grants, related jobs or scholarships.