I think this zero hours business is a red herring. People working nights get fatigued for any number of reasons - having a second job, unable to sleep due to noise at home. I've known permanent full time staff working nights who've held down a daytime job too.
And this 'ghosting' business - its a lack of supervision and management if staff were able not to turn up at work undetected.
I agree , friend of mine does zero hours contract work by choice and he wouldn't have it any other way and can't understand the stigma about it. As you say night work can be draining ZHC or not.