The 24-hour economy is placing women at an increased risk of breast cancer, a major study has warned. Researchers from Harvard University have established that regular night shifts increase the chance of developing the disease by as much as 50 per cent. The more night work that women do the higher the risk, says the study, which concludes that exposure to artificial lighting could be to blame.

Sarah P. Megdal, Candyce H Kroenke,Francine Laden, Eero Pukkala, Eva S Schernhamme, Night work and breast cancer risk: A systematic review and meta-analysis, European Journal of Cancer, volume 41, issue 13, pages 2023–2032, September 2005.