The operation was over, my gallbladder was out, and its massive infection had not killed me. I’d been free of physical pain for a week, and was days away from my “all-clear” follow-up check-in with my surgeon. My recovery, in other words, was well underway, and I ought to have been ecstatic to be free of the doubled-over agony that preceded the surgery. Instead, I felt…blank. Not happy, not sad. Not relieved, not inspired. I sat in my office and stared at the screen. Nothing. I picked up books, put them down. I watched TV images of refugees by the boatload, mothers and small children fleeing unimaginable horrors, but instead of reacting I turned off the television. When my husband asked how I felt, the only accurate response was, “Meh.” I had nothing to say, or even think, much less write.

Under other circumstances, I might have called it writer’s block. I did dutifully drag myself to my desk, where day after day, nothing came out. But over the years I’d studied and written enough about psychology to recognize this state for what it truly was: depression.

Depression does run in my family, and I’ve dipped my toe into that black pool on more than a few occasions myself. But this time there was a subtle difference, the onset so specifically twinned to the operation that I had to believe there was some connection.

I searched the Net for information about post-operative depression and found a fifteen-year-old essay from Harvard and several message boards filled with testimonies that echoed my experience. I also confirmed the assessment in one of these articles that, “Physicians are notoriously poor at recognizing depressive symptoms.” My own surgeon did a fabulous job of liberating me from my diseased gallbladder, but when I asked about depression at my follow-up meeting, he told me I was just fatigued and could expect to be tired for another three weeks. Which reassured me without ringing true. I’ve been tired before but still wanted to write. When depressed I just don’t care – about anything.

Yet the fog did lift over the next few weeks, and as I got back to work and life I kept wondering why there was this connection between surgery and depression. Nothing I’d found explained that. But several months later I raised the question at a women’s group I belong to. And every single one of the women who’d had surgery recalled the same period of apathy and despondency following their physical recuperation. So did the women in the group who’d gone through chemo. One was a science writer who explained that the culprits behind this syndrome are “inflammatory cytokines.”

Cytokines are proteins secreted by cells to facilitate communication and interactions between cells. Some trigger an inflammatory response, while other so-called anti-inflammatory cytokines prompt a reduction of inflammation. It turns out that these little proteins flood the body whenever it is severely stressed. And injury, infection, emotional crisis – and being cut open by a surgeon’s knife – all qualify as stress.

But what do cytokines have to do with depression? Back to the Web I went, and this time it cooperated. In a paper titled “Cytokine, Sickness Behavior, and Depression,” one Dr. Robert Dantzer wrote: “There is growing evidence that major depression is associated with significant elevations in circulating levels of proinflammatory cytokines.” And the significant elevation of these cytokines occurs as part of “a highly organized strategy of the [body] to fight infection.” Which is why everyone in my women’s group had experienced the same sort of low-grade depression following our respective medical crises. Some level of depression following a major assault on the body, e.g. surgery, is not only normal but should be expected.

The good news, as my gradually lifting spirits proved, is that the anti-inflammatory cytokines kick in once the inflammatory response is no longer needed. At least they’re supposed to. But in people who have chronic inflammatory ailments such as arthritis, those anti-inflammatory cytokines may be suppressed. In this case, a dose of aspirin or ibuprofen could actually function as a mild anti-depressant.

The cytokine-depression connection appears to be fledgling science, which is especially unfortunate when you consider that more than 50 million people undergo surgery every year in America alone. If their experience is anything like mine, that adds up to far too many needlessly bleak days and lost hours. At least if I’d known that depression was a natural – and temporary – part of the recovery process, I wouldn’t have worried that my writing career was permanently over. I might even have relaxed enough to enjoy the involuntary vacation.