Legal Provision on Continous night shift

what is written there in the contract?

Hi

In all the contracts of employment i.e the appointment letters or standing orders, there's always a clear stipulation, requiring an employee to come in shifts, as per the business requirement.

My query is regarding the legal position on this matter and not the contract between the parties.  

The Shops and Establishment Act only puts an embargo on the number of hours of working in a day, in a week. But there are no restrictions on the continuous night shifts.  If an organization has to work only in the night so it will be.  It is for an individual either to take it or leave it.   In fact in Railways, many Drivers and Guards work only in the night trains.