I wonder how many of these so called discoveries are more motivated by the Lawyers than a basis in fact.
People working extensive hours are going to be subject to stress probably poor lifestyle diet etc.
People who regulary work nights will soon adjust to that time scale. In some countries there is dark or daylight around the clock.
My guess is that this has more to do with stress, excessive workload and lifestyle making people more prone to developing illnesses including cancers.
They are probably motivated by the Lawyers who stand to make a lot of money targetting organisations who can pay and who iemploy scientists to create the answers and arguements they want.
Pace