Menstruation is a natural part of the life cycle of all women. It typically commences between the ages of 10 and 14 with the onset of puberty and ceases between the ages of 45 and 55 with the onset of menopause. On average, the normal menstrual period lasts from three to seven days and occurs every 28 days. The process of menstruation is controlled by a complex set of factors that include the woman's hormonal system, reproductive organs and brain. This process can be thrown off by a number of outside conditions, including stress.
Double periods are typically defined as having more than one menstrual period in a month. Because every woman's body is different and because the complex set of factors involved in menstruation can be affected by circumstances such as stress, it is not uncommon for the menstrual period to be thrown off from a day to a week or more. In some cases, a woman may begin her period after 26 days and then have another period after another 25 days. Because both periods have occurred within the same month, she is considered to have a double period. It is possible that this "double period" was the result of outside forces, or it could simply be normal for her body.
Excess stress can have an effect on the hormonal system, which can, in turn, affect a woman's menstrual cycle. Stress can cause the adrenal glands to produce cortisol, which can directly affect the impact of such sex hormones as estrogen and progesterone that can affect a woman's monthly period. In most cases, stress causes a delay in the menstrual period, but it can also result in multiple periods in one month.