I was in a similar situation, although I got more than 3 hours of sleep. I don't think 3 hours of sleep per day is sustainable, you have to find another solution. Any work you do on 3 hours of sleep is probably not great anyway.

I don't know your specific circumstances, but I used low dosage Armodafinil and Melatonin before with with success to get by with little sleep (didn't keep track, but I think at least 6 hours per day). If you are in the US you will need a prescription for Armodafinil, but if you explain your situtation to the doctor it is easy to get one. Armodafinil can be imported cheaply from India. Melatonin is over-the-counter.

Hang in there and good luck!

If you don't stop you might loose any chance of a meaningful life and job for the rest of your life. A burnout is not always possible to recover from.

Stop it, now! You'll always have a second chance but please don't destroy your body.

Wish more emphasis was on this. The posture, back, legs, sight, digestion... these all deteriorate from extended sitting in front of the monitor and a bad diet.

How are you only getting 3 hours of sleep per day? Genuinely curious. Why does your visa matter so much you're willing to harm yourself in a possibly very serious way? I suggest you take a step back and seriously weigh your options.