Did exploding stars cause a mass extinction? Cosmic radiation bombarded Earth after supernovae millions of years ago

An investigation led by researchers at the University of Kansas has deduced exactly what the impact of the supernovae events would have been, using computer models. According to Professor Melott, the two stars that exploded would have caused blue light in the night sky, which was bright enough to disrupt animals' sleep patterns for a few weeks. But the major effect of the supernovae would have come from radiation.