Dunwall

I'm in the summer of my fourth year in a PhD program in biology. I have been developing an assay to screen for a certain recombination event, and it has been going poorly. Cell lines keep getting contaminated, test after test with the same strains produces results that are inconsistent, and may not prove to be statistically significant enough to pass peer review in a journal article. So after four years, I have no reliable data. I am physically and emotionally exhausted. I don't eat enough during the day, I get only four hours of sleep a night because I'm too tense, and I have pretty severe anxiety symptoms that I have been in therapy for years on. My advisor is less than helpful, and we have no grant money. What can you do when frustration and burnout strike? What happens when it looks like a research project may not produce significant or even verifiable results?