My cycle is so light i don't have to wear a maxi pad. its all ways heavy except for this time first four days has been light. is it stress?

Great problem: What a nice change for you since normally or periods are very heavy. If you're concerned you might be pregnant then check a pregnancy test otherwise enjoy the change.

Light period: Stress can be blamed pretty much for everything, so i guess it can be, but less likely. If there is a chance of pregnancy, do a pregnancy test. Sometimes implantation bleeding presents like a light period. If negative, wait for the next one. Chances are it will be back to normal.

Can be hormonal: If you're on a new birth control pill, your period may be lighter. Stress can alter the length of your entire menstrual cycle, making it longer or shorter than usual. The amount of tissue buildup inside your uterus can vary also. This is where the bleeding comes from in the first place. Have you had unprotected sex? Pregnancy possible too. Can check a home test, or see your doctor. Be well.