I started my training as a registered nurse when I was 18. For the 3 years of my training, 3-4 months of every year was spend working night shift (7pm to 7am). I always slept badly during the day, and still do. I fit very well into the category, my first symptoms were in my 20's, and now at 55 I have SPMS
Teenagers seem to carry with them a feeling of immortality.
I never consciously thought about it, but I did not hesitate to work at night or even all night. I did not work on a shift until my teen years were a memory, so I wouldn't fit in this study. Regardless, I worked many night hours, though never on a regular routine.
And what do you know — I have MS.