YES! Stress can most certainly cause a missed period. It sounds like you might be worried about pregnancy. If you have taken home tests, and it\'s been 4 months since you last period, chances are that you are not pregnant. Exercise can also cause a missed period, particularly if you are working out more strenuously that usual (or resuming a regimen after a lengthy pause). However, there are many other medical causes for missing a period, such as your thyroid level. I would recommend seeing a doctor for a simple blood test to diagnose the problem. He or she will most likely do a pelvic exam as well to ensure your ovaries and cervix are normal. When I was 17, I went 3 months without a period. The cause was never determined, but I went on a regimen of provera (not to be confused with depo-provera), which induced my period.