There are several causes of an early period. It could be stress, changes in your lifestyles, or a hormonal imbalance triggering menorrhagia along with irregular cycles. Although the average cycle is 28 days, it is perfectly normal to have a cycle that is as short as 21 days or as long as 35 days.You do not state your age. If you are a teen or a woman in her 40's, you may have a cycle that change a lot due to hormone imbalance problems.On the other hand, an early period could be a sign of early pregnancy (i.e., implantation bleeding) or a miscarriage.ou do not state your age. If you are a teen or a woman in her 40's, you may have a cycle that change a lot due to hormone imbalance problems. On the other hand, an early period could be a sign of early pregnancy (i.e., implantation bleeding) or a miscarriage.