Is there an adverb that means at an irregular interval of time? I am asking, because I am pretty sure "periodically" means at a regular interval of time, like roughly 1 hour, even if it can be used that way, it's too ambiguous to my liking, but what if you want to say "at an irregular interval of time" like anything from "1 second to 1 week"?
For example:
He laughed ___ as he was swinging on his chair.