Working night shifts may increase the risk of ovarian cancer, according to this research. The study of more than 3,000 women found that working nights increased the risk of early-stage cancer by 49 per cent compared with doing normal office hours.

Parveen Bhatti and others. Nightshift work and risk of ovarian cancer, Occupational and Environmental Medicine, volume 50, pages 231-237, 2013 [abstract]. BBC News Online. Risks 598.