Nights are getting brighter and most of us no longer experience true darkness. Paul Bogard (James Madison University), author of The End of Night: Searching for Natural Darkness in the Age of Artificial Light, says the lack of darkness at night is affecting our physical, mental, and spiritual health. And: Centuries ago, nighttime was a scary and dangerous time. A moonless evening could be filled with perils. In his book, At Day’s Close: Night in Times Past, historian Roger Ekirch (Virginia Tech) sheds light on how pre-Industrial Revolution farmers, tradesmen, and laborers spent their nights.

Later in the show: When women compare themselves to other people, they actually lose IQ points. Read Montague (Virginia Tech) completed a study that suggests being in groups can temporarily lower our IQ. Plus: Classical guitar music was a constant in the Renaissance and Baroque eras of England, France, and Italy. Music professor and guitarist Tim Olbrych (The College of William and Mary) offers a brief history of this instrument and plays selections from his CD, 500 Years of the Spanish Guitar.