I read somewhere people with ADHD often have either a delayed circadian rhythm or one thats longer than 24 hours. No amount of pigeonholing life into the usually prevalent circadian rhythms is going to fix that I think.
Startup idea: We slow down the earth's rotation to adhere to these longer cycles.
If he's been doing this for all his life, and if the amount has been taxed appropriately, the whole thing becomes murky - he isn't hiding assets in that case, just following habits. But then I guess she could argue that it is his money anyways, regardless of it being in his mothers account.