Most days, we go about 16-18 hours without sleep. Then our biological rhythms compel us to hunker down and get some shuteye. But what if you refuse? Or, worse, what if you're unable to sleep? This is the question that inspired some grueling sleep deprivation experiments in the 1950s and 60s. Perhaps the most famous is the world record set by the New York DJ Peter Tripp. He stayed awake for 201 hours (8.4 days). He spent most of the ordeal in a glass booth in Times Square, and the rest in a hotel room across the street being monitored by scientists. After three days, Tripp began laughing hysterically at nothing at all. He also became upset, confused and paranoid. He hallucinated - at first, simple patterns like cobwebs on people's faces, or insects which were really specks of paint on the table. But soon, they became more intense, like waking dreams. He famously saw mice and kittens scurrying around the room. ...