Structure of Haemoglobin: Haemoglobin is an aggregation of four globular proteins (typically two alpha and two beta subunits), each with an embedded haeme group. Each haeme group allows the binding of an oxygen molecule.
Here's another intriguing case from the Guinness World Records. In 1964, a 17-year-old high school student named Randy Gardner beat the world record for sleep deprivation by staying awake for 264 hours (11 days) without using any stimulants.
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.