Shannon was a habitual early riser. During the week, she liked to get in a half hour of yoga before getting ready for work. It helped her deal with the physical stress of sitting in front of a computer all day and the mental stress of the complicated projects she worked on. Saturday and Sunday she slept in a little but not much. She liked her cup of coffee on her patio in the morning, sometimes even rising early enough to catch the end of sunrise.

But this morning, when she ...