Just to be clear, the OP said husband commutes, she didn't say he drove, so my contribution may be irrelevent to her situation. It might be something to think about for someone whose partner does drive though.
LondonMan to a certain extent I agree. However, childcare is a job where being so tired you make mistakes isn't good. The idea that one night's missed sleep is so awful for a working man and two years missed sleep is perfectly fine for a SAHW is one that our culture seems to have accepted.
Surely there aren't many mistakes you can make within your home that cause you to transition from alive to dead (or or irreversibly on the path to death) as a consequence of eyelids drooping for a few seconds?
london man stay at home patents do tend to drive too, you know. Usually with the precious dc in the car.
No-one should be driving if not in a fit state, I would imagine journey with children are usually more optional for a SAHP?
Realistically, how many people will take a day off work, if they think (but aren't sure) that there may be a problem with the return journey? In my experience I'm usually fine in the morning no matter how little sleep the night before, the afternoon is a very different matter, but it seems very unpredictable how much affected it will be. I've had days after a bad night when I've been fine, and others where, after only having an hour too little sleep the previous night, I've been in severe danger.
The only way to guarantee you will be safe is to not to commit to a long drive on the day after a bad night. These days if worried I just tell work I'm working from home - my bad nights are caused by their call-outs, rather than DC, in any case.
Just after I graduated, I was in a car write-off where I was woken up by car hitting the crash barrier on opposite side of the road at probably 70mph, before bouncing back across the road and coming to rest against near-side crash barrier, facing the way we'd come. Had there been oncoming traffic it could have been a head-on at a combined 140mph. I wasn't driving, but only because 10 minutes earlier, when I was, when told by my co-driver to go left at a fork I said "yes, left" and went right. At that point I handed over to what turned out to be equally impaired co-driver. (Co-driver broke leg in several places and walked funny for a couple of years, I was fine)
I think what I know that some other drivers don't, is that even when you know what state you're in, because eyes are drooping and you've had a couple of lane-drifts, and you know you might die any second as a result of failing to keep your eyes open, that knowledge still won't necessarily enable you keep your eyes open. You would think there would be enough adrenalin to wake you up, but it doesn't seem to work that way. (Though an actual fright from a near-miss does seem to help.)