A friend mentioned she had taken a new position and it requires her to work overnight. She has never worked overnight before so we both did a little research about the physical aspects of changing to a night job.
Working overnight is counter to your natural circadian rhythm. Your circadian clock is essentially a timer that lets various glands know when to release hormones and also controls mood, alertness and body temperature. Overnight workers are more vulnerable to disease. They may be sleepy, grumpy, and unable to concentrate as well as someone rested.
Some overnight workers develop a work sleep disorder characterized by insomnia and excessive sleepiness. They may be more accident prone and less able to concentrate.
Research and experiments have been done to essentially reset some body clocks. Imagine how hard this would be for someone that changes shifts frequently? Also, think of the people that do work overnight. Police and medical staff at hospitals come to mind first. These are the very people we need to be most alert and capable of successfully performing their jobs. It could be a surgeon performing a life saving operation at 3am.
It makes you appreciate the people that do go to work overnight each night to protect us or care for us.