That’s not something to wish for. (Lolcat speak: “DO NOT WANT”.)
The off switch in a human mind enables one to spread tar on a roof or rub up against razor-sharp aluminum fins on an AC unit and not care. It would also enable you to clean up whatever crap you’re paid to clean without caring or remembering. You might see that as a potential boon to your mental health, but it isn’t. That on-switch of yours really provides you with a bank of fodder for translation into humor. Hearing about people yelling at you during the witching-hour is funny. As funny as it was to hear about a Murse having to pull excrement from a patient after a week long stay at a hospital. Yes, i did say PULL. And not in clumps; like tug-of-war pull when you wrap the rope around your arm and give it your all. (true story, btw.)

Regarding the graveyard shift, ideas, and sleep.

Keep a little notepad and pencil with you all the time. When you come up with something, (great, OK, or even if you think it’s not good…) write it down. Moving the idea from your head to something else does two things. The first is it frees up your temporary memory (humans can hold six or seven items in short-term memory, really good waiters can hold twice as much). Which will increase the incidence of new (again, not necessarily good, but new nonetheless) ideas. The second is it will allow you to have a clear mind before going to bed. So your precious few hours you are allowed to sleep will be spent sleeping, rather than in a waking dream about the ideas you have to keep in memory before they are committed to paper/blog/wacom/whatever.

And there is no “as long as it pays well” if the work is piling up. A lot of people I know try to come at me with this mentality, but Jesus Christ, I hope they aren’t serious. I could show up and work every possible shift at my current job, but I also know that I’d not have time to do important things, like honing my writing, cleaning my apartment, etc. I also know that all the time spent around my co-workers would quite likely drive me insane. A hefty paycheck is nice, but certainly not worth the cost of your mind and the time you need to do important, personal things.

And I’m just fighting through it all until the middle of June when everyone comes back from their leaves of absence and I go back to my 3-4 days a week schedule. Maybe then the balancing act between work and comics will be a little less difficult.