A new study has found that irregular sleeping patterns maybe linked to cancer. This adds to concerns about the damaging impact of shift work on health.
The study conducted on mice suggests that poor sleeping patterns have been unequivocally shown to lead to cancer, and scientist have warned women with a family risk of breast cancer to never take up work shifts, the BBC reported.
However, they added that further human tests were needed.
The risk of the disease could be because of the increase in disruption of body's internal rhythm or body clock, but the link is uncertain as the type of person who works shifts may also be more likely to develop cancer due to factors such as social class, activity levels or the amount of vitamin D they get.
The study claims to be the first to show a link between chronic light-dark inversions and breast cancer development.
The researchers assume that the equivalent effect could be an extra 10 kg of body weight or for at-risk women getting cancer about five years earlier.
Dr Michael Hastings, from the UK's Medical Research Council, said that the general public health message coming out is that shift work, particularly rotational shift work was a stress and hence had consequences.
The findings are reported in Current Biology.