I think for those who do night duties, the days off you do get,
you're basically like a living dead, a zombie!
Which means, you can't do much, you're not really
yourself, you're tired like hell, and worse, it might take you some
time to adjust back to your 'normal' rhythm and by then, it's time
to do the night shift all over again! 
After a while, you feel so lethargic that what extra allowances you
might get no longer matters! 
Now that I no longer need to do night duties in my current job in
Melbourne, I sleep so much better everyday! I no longer exhibit
Narcoleptic symptoms as well. 