So basically he should never, ever, get a proper nights sleep? Because 12-6 isn't a "proper" nights sleep. When I was up at 6 I needed to be asleep before 10.
I have a small baby. The days are long and dull but the thing about having a baby is you can be a bit flexible in the way you can't when doing paid work. It can be hard work, but you don't get sacked or have your competency questioned if you underperform.
Admittedly I hated my job, but I had to be up early. I had to cope with rush hour traffic, then bitchy colleagues, nasty bosses and horrible "clients" (kids, in my case - secondary school teacher.) contrary to popular belief on here I didn't ever have time for a hot drink, or any drink.
DH isn't a secondary school teacher but he works hard - very hard, and so do I. My job is at home but it isn't work any more than cleaning my own loo is work, it's just stuff that needs doing and I do as I'm the one at home.
It's impossible to split everything down the middle as it's comparing apples to oranges, we do find it much easier for me to deal with children, housework, cooking and cleaning and DH deals with all finances. It's just how we work and it's fair.