If you go to sleep and the oxygen is replaced with nitrogen ... do you wake up while you strangle / suffocate ?
Actually no, nitrogen asphyxiation doesn’t have the ‘panic’ that is associated with built up carbon dioxide levels. You just wake up dead.
No. Anoxia produces a near instantaneous blackout.
You desire to breathe, not due to oxygen depletion, but due to Carbon Dioxide buildup in the blood. Air is roughly 80 percent nitrogen 20 percent oxygen. Your lungs exchange oxygen for carbon dioxide, the nitrogen just passes through. When you replace the oxygen with nitrogen, the carbon dioxide still comes out. You become hypoxic: sleepy, perhaps a bit intoxicated depending, then you pass out, then you die. No big deal, pretty easy way to go. Same thing happens if you lose pressurization in an aircraft at altitude. You can lose consciousness without being aware of a problem.
NO.
Nitrogen is one of the industrial hazards I work with ... All labs with nitrogen supply (liquid or dry) have alarmed O2 sensors. That's the only warning we'd get. It's odorless, tasteless, clear (duh! Air is 78% nitrogen) and doesn't cause any feelings of distress when it exceeds safe fraction of the atmosphere. It just causes unconsciousness, and eventually death. The feeling of suffocating is caused by carbon dioxide.
No. Nitrogen asphyxiation is not detected by the human body. This is due to our atmosphere being 70+ percent nitrogen. The condition is so well know that it has an MSDS sheet. From that sheet:
Exposure to atmospheres containing 8-
10% or less oxygen will bring about unconsciousness without warning and so quickly that the
individuals cannot help or protect themselves