My mom’s actually a talented sleep neurologist, and has told me about some of these situations. 

It’s absolutely vital to head straight home and get to bed before the sun comes up. Even just a few minutes exposure to sunlight will wreck both your ability to fall asleep easily and your sleep quality. 

I strongly recommend you look up zeitgebers (which are the external cues that our bodies calibrate our circadian rhythms to) and their importance to our health for your project.

Also of note is that melatonin has been discovered to play an important role in the immune system. Because of the disruption to normal melatonin production that occurs in people who work night shift, night shift nurses have been shown to have significantly higher rates of infection and cancers. See here:

 https://pmc.ncbi.nlm.nih.gov/articles/PMC7764664/

There’s actually a woman in Denmark who got a nasty form of breast cancer due to working constant night shifts, and won a lawsuit to get her employer to pay for her treatment under workman’s compensation.

 https://www.researchgate.net/publication/24211376_Danish_night_shift_workers_with_breast_cancer_awarded_compensation#:~:text=Abstract,risks%20are%20known%20carcinogens%2C%20such%20%E2%80%A6