October 25, 2011
Sunbathing in the afternoon raises the risk of developing skin cancer five-fold, a study shows.
This is because a protein the body produces to repair damage caused by ultraviolet rays is most active in the mornings, scientists say. So soaking up the sunshine or visiting a tanning booth could be safer before lunchtime, they suggest.
In tests, mice developed five times more skin cancer tumours when exposed to UV rays in the morning, compared to those given identical doses in the afternoon. The U.S. researchers believe the opposite would be true for humans because mice are nocturnal and their body clock is reversed.
Professor Aziz Sancar, who led the study at the University of North Carolina, has shown in other studies that levels of the XPA protein – which repairs damage to DNA – wax and wane throughout the day and seem to be controlled by the body clock.