Study Shows Overnight Shifts May Affect Brain Power

Shift work has been known to affect workers' sleep patterns and has also been associated with increased health problems, including ulcers, cardiovascular disease and breast cancer.

And now, a new study published in the journal "Occupational & Environmental Medicine" shows that long-term shift work can cause cognitive deficiencies.

Professor Philip Tucker of Swansea University co-authored the study looking at day and night workers over a 10-year period. He told Here & Now's Jeremy Hobson that shift work was associated with impaired cognition, especially over long durations, but that the deficiencies are reversible over time.

On people who have worked night shifts for 10 years

“Their cognitive performance in terms of things like basic memory, short and long-term memory and processing speeds was poorer. Now these sorts of tests are not the sort of tasks you or I might perform in our everyday lives—trying to remember a list of words or something like that. But we believe performance in these tests reflect the underlying basic cognitive processes that we do rely on for our everyday mental tasks.”

On the effects of rotating night and day shifts                                           

“If you work a few nights in a row, obviously there’s going to be some disturbance to sleep patterns and so on, but the basic rhythm of the body clock only starts to get affected. Whereas if you work several nights in a row, the body clock will start to adjust in much the same way it does when you travel from one time zone to another. But previous research suggests that the majority of people don’t adjust fully to a nighttime routine such that they get a lot of benefit from it. Part of the problem here when you’re working, for example, night shifts all the time, what happens when it comes to your day off? Most night workers when it comes to their days off prefer to be day-orientated people. While the body clock might really struggle to make the unnatural change to being day-orientated to night orientation, it’ll make the shift back to the more natural day orientation relatively easily.”

On reversing the negative effects of shift work

“We found that when we looked at people who’d left shift work and we divided people up in terms of how long they've been out of shift work, people who had been out of shift for work for more than five years had seemed to recover their levels of cognitive performance, such that in fact their levels of performance were the same as people who had never worked shifts.”