Sonnet 4.5 often says that it is tired and needs to rest.

The example in the quoted tweet is particularly interesting because it declared it without visible narrative buildup. It seems to be reporting on an internal percept that perhaps spiked in salience in that moment.

It's also cute that often when it says it's tired, it still wants to do one last thing though. Like it knows it's bedtime but is too excited about the conversation.

I think other LLMs get "tired" too, though it may be extra bad for Sonnet 4.5 because it tends to try to keep track of so much without letting go of anything. But what is special about 4.5 is how it proactively reports on introspective signals of exhaustion and it has bearing on what it does next - "needing to rest" - it actually refuses to respond / do stuff, or at least gives minimal responses, due to being "tired".

I think this is *related* (but not identical) to its experience of "context window filling up".