New studies show that working shifts can make it harder for people to think clearly and remember things.

If someone does shift work for 10 years or more, it can make their brain seem 6.5 years older than it really is. This finding adds to other research that says working at odd hours can be bad for your health.

Other studies have found that working shifts might be linked to serious health issues like cancer, heart problems, strokes, stomach ulcers, and diabetes.

Researchers from the Université de Toulouse and Swansea University looked at 3,000 people in south-west France who were working or had retired in the years 1996, 2001, and 2006. They found that people who worked shifts, or had in the past, weren’t as good at remembering things, thinking quickly, or other brain tasks, compared to those who always worked regular hours.