Work And Study At The Same Time?

I have experienced this last year. I was studying during the afternoon and then working at night. At first, I felt okay with it and happy but eventually felt tired. One of the reason could be because I did not have any close friends at school because my classmates are still teenagers so I am like a big sister to them. It came to a point that I was literally dragging myself to school. But this is still a case to case basis. Not all Work and study experience is tiring. depends on your work and study load.