Jia Cheng winds sticky metallic tape several times around my neck, and then again around my waist. She's about to hook me up to a battery of sensors that will track how I respond to the embarrassment of making mistakes in front of a stranger.

In John Cacioppo and Louise Hawkley's loneliness lab, the University of Chicago researchers chart the merest twitch of a muscle, an extra drop of blood to a section of the brain and the delay of a heartbeat to understand how being with people -- or being cut off from them -- changes the chemical brew that animates the mind.

Cacioppo and Hawkley don't think of it as the loneliness lab, of course. The official name for this facility is a social neuroscience laboratory, and the two professors, along with their project managers, Jeanine Pilat, Zach Johnson and Jia Cheng, examine endocrine, immunological, autonomic, and central nervous system processes and how they change from day to day as we navigate the sometimes difficult waters of relationship.

They've found that loneliness is a state of the body, as well as the mind. While everyone experiences bouts of loneliness and periods when circumstances take them out of their circle of support, loneliness can become an emotional and physical habit.

Their monitoring setup looks like a music recording studio: racks of hardware with sliders and knobs, a row of video monitors. But this rig is recording the music of human emotion, as expressed in the peaks and pulses of electrical activity.

The heart of the lab is an enclosed room behind a forbiddingly solid door. Its four inches of thickness block out sound, while copper lining the jamb and the edge of the door snag stray electrical impulses that could interfere with the delicate sensors inside.

The monitoring room is as pleasantly nondescript as a dentist's waiting room, except for the huge flat panel TV screen. It has a nicely upholstered wing chair, a coffee table with a few magazines and a side chair. The only indication of its function is a snake of cables coming through the wall behind the armchair.

Cheng attaches the end of each magnetic strip stuck to my body to a sensor, straps a blood pressure cuff to my left arm and then straps another monitor to my wrist to follow my pulse. Then, the fun begins. Zach Johnson, another project manager, enters the room, sits on the chair at my left and gives me a no-nonsense look. He tells me I'll perform a mental subtraction test, and he'll judge my performance. I've read about this test, designed to turn up the heat, so I'm not too alarmed about my performance -- but still, I'm not looking forward to the math.

The first couple sets seem relatively easy, but by the fourth round my brain is seriously tired. I have trouble remembering the number I'm supposed to subtract, and sometimes my mind just stalls. What is 738 minus 7? All the time, the sensing equipment is monitoring changes in my physical state.

I breathe a sigh of relief when the last round comes, and three is the number I need to subtract. (Evidently, this puts me at barely average in my math ability; testers adjust the difficulty as the test progresses to make sure it's stressful enough. Some people need to be asked to serially subtract 17 to become stressed.)

My test isn't exactly "fair," because I know what the game is, so I don't have the same kind of performance anxiety someone else might experience. But the point of the study isn't to determine any individual's reaction pattern. Instead, Cacioppo and Hawkley are looking for patterns. Do people who are lonelier, for example, become stressed sooner? Do they exhibit more stress trying to subtract 8 from 1,297 than do those who say they have many people they can turn to?

They've already found strong evidence that lonely people can spiral into a vicious circle of disconnection and illness. Cortisol -- the chemical that keeps us alert and helps us cope with stress, seems to be a culprit.

Cortisol is the yang to oxytocin's yin. The body needs a little boost to get it going after sleep, so the brain typically sends out a little jolt of cortisol as we wake  up. This cortisol awakening response, or CAR, is part of a daily ebb and flow that keeps us alert and able to cope with whatever comes our way. The cortisol level peaks in the first 30 to 45 minutes after awakening, and then drops over the course of the day, reaching its lowest point around midnight.

But how high those peaks and how low those troughs are a part of each person's chemical signature. Stressed-out folks often show a higher CAR; people suffering from chronic fatigue or fibromyalgia may have less variation in their daily cortisol levels.

The question is, do the body's cortisol tides contribute to these conditions, or are they the result of them? A study Cacioppo and Hawkley did with Emma Adam of Northwestern University and Brigitte Kudielka of the University of Trier showed that one day's emotional experiences set the next day's endocrine tone.

They sent 156 older adults home with bags full of plastic tubes and multi-page questionnaires. The participants spit into the tubes three times a day, and they also filled answered dozens of questions that exhaustively catalogued their days, from whether they ate junk food to whether they got support from the person who's closest to them, from a pet or from God.

It turned out that one bad day can lead to another one -- at least, when it comes to the cortisol awakening response. People who reported feeling overwhelmed, sad, threatened or lonely had higher CARs the following day. (This study didn't look at whether the subjects felt less unhappy on the second day, thanks to the extra cortisol.)

In the short term, the extra jolt of cortisol after a bad day may get us over the hump. In the long run, though, it turns into a killer. Among the elderly people Cacioppo and Hawkley study, there's a clear link between loneliness, high cortisol and chronic high blood pressure.

These studies are helping to illuminate the link between body, mind and emotion. Clearly, loneliness -- and its debilitating effects -- isn't just in the mind. Says Hawkley, "That's pretty clear evidence of psychology pushing physiology."

Photos: Zach Johnson, Jia Cheng, Jeanine Pilat and Louise Hawkley in the Social Neuroscience Lab; Hawkley opens the door to the monitoring room.