Professor Torbjörn Åkerstedt
Professor Torbjörn Åkerstedt

The study, based on data from 13 000 women from the Swedish Twin register, shows that women up to the age of 60 and who has worked night for 20 years or more is concidered to be of high risk of developing breast cancer. The risk of getting breast cancer increases with 75 per cent, from 2 per cent units to 3,5 per cent units.

- It might seem to be much, but it is conciderable less then for example smoking or asbestos, says Torbjörn Åkerstedt, professor at the Stress Research Institute.

Nevertheless, he thinks that women working night should pay attention to this risk. 

The causes of this is probably that irregular sleep disrupts the production of melatonin in the body. Melatonin is a hormone that protects the body from cancer.

The study is made in cooperation with AFA Försäkring.