© Photographer:Piero Pausin | Agency: Dreamstime.com
About 10 years ago I took a technical job at a company that was establishing a new analytical lab. Until it was ready, I had to work in the old lab that was shared by employees from another division. Because there was only so much equipment to go around, I ended up working second shift for about six months.My hours were from 4:30 p.m. to 12:30 a.m. I had never worked the night shift before. In some ways, it was all right - not very many other people around, so it was easy to get work done. I kind of liked being on a different schedule than everyone else.
But as the months wore on, the sleep deprivation began to take its toll. I was always tired, walking around in a fog. Sometimes at work I would close my eyes as I walked down the hall. It felt good (and fortunately, the halls were wide), but was no substitute for real sleep. The sterile atmosphere of the lab was magnified by the sense that the building was all but deserted, leaving me alone with my samples and my bleary thoughts.
If I had to work "late," it meant staying until the early hours of the next day. Once, I worked on a priority job that I wanted to complete overnight, but to finish the report, I wound up staying until 7:30 a.m., just in time to greet the day staff. After a 15-hour shift, my body reacted by putting me in a deep freeze.
When I got home, I ate breakfast and was shivering the whole time. I couldn't get warm. I thought about taking a hot bath, but I was so tired, I crawled into bed. With the sun shining into the bedroom, I was able to warm up and, despite the light, fall asleep.
Only later did I learn that I was experiencing my body's circadian rhythm, an internal body rhythm guided by core body temperature. As the graph shows, core temperature drops off most steeply between midnight and 6 a.m. Because of this, shift workers and med students often experience feeling cold. One med student reported putting on extra layers of scrubs so she wouldn't shiver.
Shift workers also report another strange occurrence: shift paralysis, where a worker is fully alert, but cannot move one or more limbs. This inability to move can last up to five minutes. It seems to be a case of the brain briefly shutting down because it can no longer function due to fatigue. After a short break, it can once again coordinate nerves and muscles to get the body moving.
Humans are diurnal by nature. It takes the night shift to reveal some of the mysteries of our internal clocks and rhythms. While some people can work the night shift for years with few problems, I admit I was glad to be working days again in a brand new lab that actually had some people around.
