I have a friend who once experienced almost exactly what you describe. He was pretty sure it was narcosis. It is the only time it ever happened to him, and he is a tech instructor.
No one is really sure what causes narcosis, but it is not caused by nitrogen alone. All gases have the capacity to bring on narcosis. According to the most accepted theory, oxygen has more potential for narcosis than nitrogen, but the effect is hard to measure because it is metabolized and because testing it in high concentrations is dangerous. Although there is controversy about this, that is why most people believe nitrox gives no benefit in terms of narcosis. Helium has a very low potential for narcosis, which is why deep divers like to replace nitrogen with helium on those dives.
Carbon dioxide has a high narcotic potential. That is one reason why vigorous activity coupled with high levels of nitrogen (because of depth) can lead to a higher potential for a narcotic episode. You have two factors working together.
Carbon dioxide buildup also leads to a sense of panic. If you hold your breath long enough to get that panicky urge to breathe, it is not because you need oxygen. Your body has nearly no signal for that. That panic is caused by CO2 buildup. People who are getting therapy for panic attacks frequently are taught to use diaphragmatic breathing, a long, slow breathing pattern initiated by the diaphragm and stressing a complete exhale to remove CO2.
No one is really sure what causes narcosis, but it is not caused by nitrogen alone. All gases have the capacity to bring on narcosis. According to the most accepted theory, oxygen has more potential for narcosis than nitrogen, but the effect is hard to measure because it is metabolized and because testing it in high concentrations is dangerous. Although there is controversy about this, that is why most people believe nitrox gives no benefit in terms of narcosis. Helium has a very low potential for narcosis, which is why deep divers like to replace nitrogen with helium on those dives.
Carbon dioxide has a high narcotic potential. That is one reason why vigorous activity coupled with high levels of nitrogen (because of depth) can lead to a higher potential for a narcotic episode. You have two factors working together.
Carbon dioxide buildup also leads to a sense of panic. If you hold your breath long enough to get that panicky urge to breathe, it is not because you need oxygen. Your body has nearly no signal for that. That panic is caused by CO2 buildup. People who are getting therapy for panic attacks frequently are taught to use diaphragmatic breathing, a long, slow breathing pattern initiated by the diaphragm and stressing a complete exhale to remove CO2.