AI mania is Simon Willison’s name, in 2026 in LLMs (so far), for a state in which any time your agent is not building something for you feels like wasted time, so that you lose sleep because you could be staying up later getting your agents to do things. He is explicit that it is not the same thing as AI psychosis. He describes the state in general terms and also as something he suffered from himself.
Usage
Willison describes two bouts of it in 2026. In January, his AI mania showed itself in ridiculously over-ambitious projects: a JavaScript interpreter written entirely in Python, vibe-ported from MicroQuickJS, and a WebAssembly runtime in Python. He says those projects were quite useful, in that they sort of cured him of it, because having built them he had to ask whether the world needed a slow, buggy, half-baked Python JavaScript interpreter, and concluded it did not. The second came in June, when a new model was available on subscription plans only for a limited time: he describes losing sleep again and rescheduling things so he could get as much as possible out of it before the price went up.
Earlier in the same talk, and without linking it to AI mania himself, Willison describes his New Year’s resolution for 2026: to take on as many new projects as he liked now that coding agents existed, reversing years of resolving to focus.