Nitrogen is narcotic at higher partial pressures. This is something they teach during SCUBA diving training: If your dive buddy starts acting loopy when you get around 100ft deep, it's time to go up.

> It is caused by the anesthetic effect of certain gases at high partial pressure... Narcosis produces a state similar to drunkenness (alcohol intoxication), or nitrous oxide inhalation.

> Except for helium and probably neon, all gases that can be breathed have a narcotic effect, although widely varying in degree. The effect is consistently greater for gases with a higher lipid solubility, and although the mechanism of this phenomenon is still not fully clear, there is good evidence that the two properties are mechanistically related.

https://en.wikipedia.org/wiki/Nitrogen_narcosis