Answer:
107 degrees.
Explanation:
Body heat builds up. A body temperature of 104 degrees indicates danger; 105 degrees is the definition of heat stroke; and a temperature of 107 degrees could result in irreversible organ damage or even death.
The absolute longest anyone has voluntarily stayed awake before nodding off is 264 hours (about 11 days) — a record set by 17-year-old Randy Gardner for a high-school science fair project in 1965. Before falling asleep on day 11, he was essentially a vegetable with its eyes open
But at what point would he have died?
In June, a 26-year-old Chinese man reportedly died 11 days into a sleepless attempt to watch every game of the European Cup. But he was also drinking alcohol and smoking throughout, making it difficult to ascertain his cause of death. No human has ever definitively died from lack of sleep alone, and for obvious ethical reasons, scientists can't find the breaking point in the lab.
Most humans will suffer hyperthermia after 10 minutes in extremely humid, 140-degree-Fahrenheit (60-degrees-Celsius) heat. Death by cold is harder to delimit. A person usually expires when their body temperature drops to 70 degrees F (21 degrees C), but how long this takes to happen depends on how "used to the cold" a person is, and whether a mysterious, latent form of hibernation sets in, which has been known to happen.
The boundaries of survival are better established for long-term comfort. According to a 1958 NASA report, people can live indefinitely in environments that range between roughly 40 degrees F and 95 degrees F (4 and 35 degrees C), if the latter temperature occurs at no more than 50 percent relative humidity. The maximum temperature pushes upward when it's less humid, because lower water content in the air makes it easier to sweat, and thus, keep cool. [Infographic: Human Comfort Zones.
We pass out when the pressure drops below 57 percent of atmospheric pressure.
