More people are working on shifts, including nights. While work is work, its constantly-changing schedule does a lot of harm to the body, including negative impact on cognition: it's as if the workers are always jet-lagged.
The report says that many studies have already proven that changing work shifts, especially night jobs, can increase the risk of obesity, certain types of cancer, and cardiovascular disorders.
To determine if work shifts have some consequences to cognitive abilities, a group of researchers from Wales Swansea University's psychology department studies more than 3,000 workers in different parts of Southern France. These subjects were either retired or employed during the study. They also participated in an annual medical exam for 10 years since 1996. Less than 50% of these workers handled shifts for 50 days each year.
The subjects of the study then underwent a series of exercises or tests that measured their cognitive abilities, such as their memory and speed of processing information. The researchers conducted the first examination in 1996 when the participants' ages ranged from 32 to 62 years old. They repeated the same examinations twice after, on the fifth then on the tenth year.
They discovered upon analyzing the gathered data that sleep impairment caused by working in shifts can have a profound negative impact on cognition. In fact, the effects can be likened to experiencing chronic jet lag. One of the possible reasons for this is a person's body clock or circadian rhythm. The body is designed to relax, slow down, and sleep as the day gets darker.
Moreover, a person who takes on night shift work for 10 years can experience a cognitive decline equivalent to almost 7 years.
However, based on the same experiment, it's still possible that the effect can be reversed five years after the workers leave such type of work schedule.