Of all the things that keep you up at night, you should add gamma-ray bursts to the list of terrible things that are actually real and scary (though incredibly unlikely). These intense explosions are thought to be the the deaths of massive stars and the birth of black holes. They are only observed far away from the Milky Way which is good because if one were to occur in the Milky Way it would probably destroy most life on earth.
On April 23 the NASA Swift satellite detected evidence for the
most distant object ever observed. It was indeed a gamma-ray burst. It has a redshift of 8.2, that means it occurred about 200-300 million years after the Big Bang (for reference on the
distance scale that places it somewhere roughly between the lines marking the cosmic microwave background and the first stars).
If you want to know more casual information about gamma-ray bursts try
this. The gory gory details can be read on the arXiv
here and
here, but don't tell them I sent you because the article is pending publication in Nature and there is an
intellectual embargo.