Any studies concluding a corelation between being awake at night and poor health are likely measuring many confounding factors. There’s no way to isolate that variable. Certain groups are more likely to stay up into the night, which could equally be the cause. It also requires, as the post implies, giving up certain activities. Those activities may promote good health in some way.

Any actual medical condition caused by nighttime activity could be managed, like vitamin D deficiency. The societal factors can’t be, although if it was more common and acceptable that could level out some of the variables.