Quitting after 5 years - miserable and depressed
&quot;I work 10-6 pm everyday and I know that's not a lot in the PhD world, but I feel like I am not productive beyond that.&quot;
This is a particularly important insight.
When I had successfully defended my prospectus and was officially &quot;all but dissertation&quot; (with the privilege of working on my own self-selected and self-directed topic, with input from my committee) I discovered pretty quickly that for this research—about which I was both intellectually and emotionally passionate—I had about 4 to 5 hours of productive work to give to my dissertation each day. Moreover, simply sitting at my office desk not being productive did not actually measure up as &quot;productivity&quot;.
So I adjusted my expectations to 4 to 5 hours of productive work, and gave myself license for other pursuits for the other hours of my day. Some of these other pursuits were academic: that software I wanted to write; the syllabi for those courses that I wished I could have taken, but they didn't exist, so I wanted to teach them some day; reading to learn new theories, methods, and substantive research; taking courses and attending intensive workshops. All of these &quot;extra&quot; activities have parlayed directly into my subsequent academic work and hires.
Some of the other pursuits were not academic: I walked in the park, went to museums, engaged in art, sport and activism, maintained interpersonal relationships. All of these extra &quot;extra&quot; activities have indirectly parlayed into my subsequent academic work by supporting my mental and physical health, and my development into a well-rounded individual who brings a good deal of experience to the classroom, to the research team, and to my work-fellows. These activities have also sometimes parlayed directly into subsequent academic work through the development of what would become collaborative relationships, introductions to professional networks, and by planting the seeds of research or pedagogical substance.
The idea that you must be a soulless drudge in the academy is certainly a perspective that has its exponents. Academic and activist David Graeber has an interesting perspective on labor time that I think is apt here (and I think it is important that we not forget that we are also labor):

In the late 19th and early 20th centuries, one of the great divisions between anarcho- syndicalist unions, and socialist unions, was that the latter were always asking for higher wages, and the anarchists were asking for less hours. That’s why the anarchists were so entangled in struggles for the eight-hour day. It’s as if the socialists were essentially buying into the notion that work is a virtue, and consumerism is good, but it should all be managed democratically, while the anarchists were saying, no, the whole deal—that we work more and more for more and more stuff—is rotten from the get-go.
—Frank, T. (2014). David Graeber: “Spotlight on the financial sector did make apparent just how bizarrely skewed our economy is in terms of who gets rewarded”: David Graeber explains why the more your job helps others, the less you get paid. Salon.com, Sunday, June 1st.

To situate my response: my doctorate, completed in 6 years (about median for my cohort) was from Harvard, I readily obtained a post doc, and just as readily obtained a tenure-track faculty appointment in which my &quot;extra&quot; activities alluded to above have contributed in recognized ways to my evaluation and tenure process.
So this answer is not telling you to leave or to stay. Neither is it telling you how to proceed should you stay. But it is attempting to give you license to both value your academic and researcher self as part of a richer and more whole human being, and to reject value systems that tell you otherwise.