The market is generally single parents working 3rd shift jobs. It is financially and operationally unstable, so most night providers wash out in under a year.
(FYI: The majority of regular shift childcare providers wash out in two years
so don't be too alarmed. It is an unstable career field in general.)
One big hurdle to night care is that most state regulations say each child must be given their own bed, not a cot, and the provider must be awake at all times.