ANSWER:

As long as you are paid to work 12 hours, you can’t leave even if he allows you as he is not the owner of the business. You need to clear this up with the management of the hospital and if they give you the green light, this is permissible 

QUESTION: I’m an intern doctor,  we have our night duty from 8 pm to 8 am,, but after finishing most of the works in few hours , my senior said that ( indirectly)  i can leave and rest in my room, and can come  in the morning … Am i sinful?  Is my money of that day halal?Nb: i didn’t ask for leave,,