Forgive the small trivial post, but I've found that when I'm tired or physically exhausted, that's when I'm most susceptible to be little.
Compare with when I've had 10 hours in bed and hopped-up on caffeine (and optimally: working on an interesting technical problem at work/hobby) - I actually have a negative desire to be little.
Let's not make this a "Does anyone else" thread because I know this is true, but I'm wanting to know what is the "optimal" amount of tiredness to aid littleness? I find it's "worst" (or "best" depending on your perspective) after several consecutive days with 5-6 hours sleep.
What works for you?