Why does it often feel like the world knows nothing about the menstrual cycle? Well, the easy yet disheartening answer is: the menstrual cycle has not been a key area of focus in research. This is quite ironic, since this process is experienced by over half the population and has been around since the start of human existence. So much could be said about the stigma surrounding the menstrual cycle and its history, but for today’s article, I want to break down the menstrual cycle in a digestible way.
The menstrual cycle is not a closed process that only needs the help of the uterus, but rather requires a specific region of the brain called the hypothalamic-pituitary-ovarian (HPO) axis. Constant communication between this region of the brain and the ovaries ensures the occurrence of each cycle. The menstrual cycle can be broken down into four main phases: the follicular phase, ovulation, the luteal phase, and menstruation. Different hormones are responsible for triggering the start of these phases. For the sake of not overloading you with information, I’m going to talk about the rise and fall of estrogen throughout the cycle, but there are many more involved (like progesterone!).
In a perfect world, doctors like to put the normal length of the follicular and luteal phase from anywhere between 11 to 14 days, but most cycles vary greatly from this. The follicular phase begins when your period stops. In this phase, many women feel more energized and motivated. This spike in energy can be accounted for by the hormone estrogen, which is highest during the follicular phase. Estrogen has many impacts, but most notably, this hormone is known to cause an increase in motivation, metabolism, and energy. Ovulation is the day when an unfertilized egg is released from the ovaries. If there is no fertilization, the luteal phase occurs, which will eventually lead to your period arriving, also known as menstruation.
Do you ever get moody right before your period starts? How about just downright exhausted? Those symptoms are actually incredibly normal to experience during the days leading up to the first day of bleeding. For many, these feelings can be due to the fact that estrogen levels begin to decline throughout the luteal phase (remember how key estrogen is in providing energy).
Of course, everyone experiences their cycle in a myriad of different ways, and you may be reading this thinking you have never felt mood changes before your period starts. But oftentimes, knowing this can allow you to realize that the lethargic, unmotivated feeling you have that week before your period begins is not because you are lazy, but because your hormone levels are fluctuating!
Of course, this article’s explanation of the menstrual cycle is extremely simplified. If you want to learn more about how the menstrual cycle works, here are a few book recommendations:
Seeing Red by Kristen Karchmer
Period Power: A Manifesto for the Menstrual Movement by Nadya Okamoto
Hormonal: The Hidden Intelligence of Hormones by Martie Haselton