What keeps you up at night?

I recall a conversation I once heard on a talk show many years ago.  It was Dick Cavett Show.  He had three nuclear scientists on the show discussing the awful state of nuclear proliferation.  What is your greatest fear, Cavett asked the scientists.  The first scientist responded without hesitation: "Thermonuclear war, without a doubt."   "Yes," the second scientist joined in agreement.  The third scientist sitting to the far left from Cavett appeared sheepish and remained silent.  When pushed for a response the scientist confessed: "My esteemed colleagues are entirely justified to be fearful of thermonuclear war.  But the thing that I fear most of all," he said as he began to break up, is not being loved."