I was called one evening to evaluate an elderly patient who suddenly was not able to wake up.

He had major surgery three days earlier, and seemed to be doing well. Just an hour before I got the call, he was having a conversation with his nurse.

Now he could barely open his eyes or answer my questions. I kept raising my voice and tapped on his arms more vigorously. I even pinched him lightly to get a response. But no matter what I tried he would only stir for a moment, mutter something unintelligible, and then quickly become unresponsive.

Afraid that he had suffered a major complication, I called the stroke neurologist on-call who came to do a thorough evaluation.

“What do you think? Is he having a stroke?” I asked

The neurologist shook her head. “His exam does not seem to follow the pattern of a stroke.”

“What could explain his inability to stay awake?” I asked.

“Well, it’s normal for you to be alarmed by this, and we should get a head scan to rule out something serious,” she said, “but if everything checks out, maybe he is just really tired, and sleep deprived.”

Because of the high-risk nature of the surgery and the type of close monitoring it required afterward, we had been waking him up every hour for a brief physical exam. He had not had more than one hour of uninterrupted sleep over the last three days. Though the wake-up calls were medically appropriate, I decided to let him sleep.

Sure enough, a few hours later, the patient woke up on his own. He had no recollection of the entire ordeal.

Sleep, or the lack of, used to be an afterthought in the way I treated patients.

Though I constantly follow their vital signs, including temperature, heart rate, blood pressure, respiratory rate, and pain, I was not keeping track of sleep, or considering whether sheer fatigue could be contributing to confusion or lack of energy. Now, I better understand how important sleep is to my patients’ recovery.

I used to overlook the importance of sleep in my own life, too.

Many health care providers struggle to find time to sleep. Those of us on hospital shifts have to flip from working days to nights as often as every few days, relying on coffee and melatonin to get through the week.

My patient’s experience helped me see that the countless nights we stay awake working are not a trivial matter. We begin to have symptoms, too. When I do not get enough sleep, I, too, become sluggish, unmotivated, forgetful, irritable, and more. Yet I was ignoring those important signs in my life, just as I hadn’t considered them in my patients until I thought one might be having a stroke.

Now, able to better empathize with my patients’ experiences in the hospital, I consider sleep as another vital sign for them — and for me.

Jason Han is a cardiac surgery resident at a Philadelphia hospital and contributor to The Inquirer’s Health section.