Shift work erodes cognitive ability, study finds
Working an irregular schedule that includes afternoon and night shifts can seriously sap your brain power, research shows.
For people who spent more than a decade on this type of rotating schedule, the effects were equivalent to 6.5 years of normal, age-related cognitive decline, according to a study in the journal Occupational & Environmental Medicine.
Even people who spent at least 50 days in a single year working any type of irregular work schedule — including regular shifts that prevented them from going to sleep before midnight or that forced them to wake up before 5 a.m. — suffered a significant mental toll. Tests revealed that these workers experienced the equivalent of 4.3 years of age-related cognitive decline, on average, even if their shift work happened years ago.
Researchers found evidence that people’s brains can recover after their work schedules return to normal. People who hadn’t worked rotating shifts for at least five years had cognitive test scores that were about the same as those of people who had never worked such a schedule.
People who were working a rotating schedule had worse scores — the equivalent of 5.8 years of age-related decline. Even worse were people who had stopped working a rotating schedule within the past five years; their scores indicated the equivalent of 6.9 years of age-related cognitive decline.
When the researchers expanded the analysis to include people who experienced any kind of irregular work schedule, the results were similar.
All of the data came from VISAT, a long-term study of salaried workers from southern France. The workers, who held a wide range of jobs, were given questionnaires and clinical exams as many as three times in a 10-year period.
Work schedules that are out of sync with the body’s natural circadian rhythm can harm mental function.