>It is well known that your psychological state influences the immune system a lot, and even from anecdata, you can see that people rapidly deteriorate when they give up. It is not a coincidence all these terms are used.
Brief naturalistic stressors (such as exams) tended to suppress cellular immunity while preserving humoral immunity. Chronic stressors were associated with suppression of both cellular and humoral measures
The more a stressor deviated from those parameters by becoming more chronic, however, the more components of the immune system were affected in a potentially detrimental way.
citation needed. This meta study seems to not have found many biological links: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1361287/