Underwater explorer and photographer Jill Heinerth has dived into unmapped caves deep in the earth, and beneath a giant iceberg. She's seen hidden creatures old as dinosaurs, and witnessed scenes of surreal beauty. Her work is so dangerous, over a hundred of her friends and colleagues have died in caves. She talks about the risks and rewards of her work.
We tend to think of being asleep or awake as an either-or prospect: If you're not asleep, then you must be awake. But sleep disorder specialist and neurologist Guy Leschziner says it's not that simple.
Dr. Thomas Boyce, an emeritus professor of pediatrics and psychiatry at the University of California, San Francisco, has treated children who seem to be completely unflappable and unfazed by their surroundings — as well as those who are extremely sensitive to their environments. Over the years, he began to liken these two types of children to two very different flowers: dandelions and orchids.