Nitrous tends to produce some sort of ambient auditory hallucinations, often in a way that directly corresponds to feelings of physical euphoria. A sort of rippling-breathing almost echoing effect is common, but often a hallmark of a really good hit is a sort of ringing sound that tends to be accompanied by a particularly pleasurable and relieving feeling. It's really addicting in the short term, but most people are kind of over it after a couple hours.

You can definitely lose track of how much you're spending in that time, though. Many do.