Days before your period you may feel as if you’re walking around in a mental fog. During premenstrual syndrome (PMS), hormones begin to fluctuate and alter the levels of brain chemicals that keep you balanced and alert, but what exactly happens to the brain during your period?

The Menstrual Cycle: Menstruation

Typically, women go through monthly bleeding as the body sheds the lining of the uterus while menstrual blood flows from it through the small opening in the cervix and through the vagina. Most menstrual periods last from three to five days, says the Office on Women’s Health, with the average menstrual cycle lasting 28 days long. A regular menstrual cycle exists when periods come regularly, hinting important parts of the body are working normally. It is the very rise and fall of hormone levels during the month that control the menstrual cycle.

The Highs And Lows Of Estrogen And The Female Brain

The levels of estrogen, progesterone, and testosterone — the three major hormones that control the menstrual cycle — are relatively low during the first day of bleeding. Usually, after the first few days, there will be a surge of estrogen levels that will stimulate the release of endorphins that eliminate the mental change or hormonal cloud present during PMS.

“Estrogen levels are closely linked with women’s emotional well-being as estrogen affects parts of the brain that control emotions,” Dr. Ben Michaelis, a clinical psychologist in New York City and author of Your Next Big Thing, told Medical Daily. He believes the first few days of menstruation usually mark the “happy time” of the month, as some women report feeling more energetic, happy, and even inspired. This is why the rise in estrogen levels helps suppress stress hormones adrenaline and cortisol.

The effects of the female hormone are so potent when it comes to brain health. A 2000 study published in the journal PNAS found estrogen increases synaptic connectivity in the hippocampus by 25 percent. The hippocampus is involved in short-term memory and decision-making.

The rise in estrogen levels during the menstrual cycle deters women from impulsive decision-making. A 2014 study published in the Journal of Neuroscience found greater increases in estrogen levels across the menstrual cycle compared to impulsive behavior during the beginning of menstruation when estrogen levels are low.

However, low estrogen levels during the beginning of the menstrual cycle can provide benefits. Women tend to display greater brain activity when thinking about positive experience such as winning money at the start of their cycle than women who are in the other stages of the cycle. A 2008 study published in the journal PNAS confirmed what determined if a woman is an impulsive decision-maker is what stage of the cycle she’s in and her estrogen levels. The higher the estrogen levels, the less impulsive a woman is likely to be.

The Rise Of Testosterone And The Female Brain

While estrogen increases synaptic connectivity, testosterone production increases a woman’s sex drive during her period, as progesterone is lowest during this time. The combination of both increasing estrogen and testosterone levels leads women tend to feel more sexual. Pelvic congestion, or the heaviness felt during menstruation can trigger or translate to arousal. “The rise of testosterone, one of the hormones that regulate sex drive, is associated with an increased libido in women and greater sexual arousal,” Michaelis said.

Moreover, it’s believed because of the additional lubrication from menstruation, this makes penetration more comfortable.

Period Pain And The Female Brain

Period pain is very common and often experienced by about three out of four girls and women who experience a varying intensity at some point during menstruation, according to PubMed Health. Many girls and women experience common problems like abdominal cramps and pain. However, whether the pain is mild or severe, period-induced pain can cloud your cognitive functioning.

According to Michaelis, “Menstrual pain and cramps may be associated with brain changes.”

Women who get painful menstrual cramps are more likely to show changes in the volume of the brain’s gray matter. This part of the brain is brain tissue made up of nerve cell bodies as opposed to fibers that are involved in the transmission and control of pain, including emotional responses. For example, a 2010 study published in the journal Pain found there were abnormal gray matter decreases found in regions involved in pain transmission, higher level sensory processing, and affected regulation, while increases were found in regions involved in pain modulation and in regulation of endocrine function in the pain group.

Period pain does not only affect gray matter, but overall cognitive functioning. Common everyday pain experienced by women each month affects their ability to perform a range of complex tasks. A 2014 study published in the journal PAIN menstrual cramps have a noticeably negative effect on a woman’s ability to perform tasks. Women with period pains had a lower performance rating comparable to their non-period counterparts as they struggled with attention-based jobs, such as competing targets and dividing their attention between two tasks.

Menstruation And Brain Power

A woman’s menstrual cycle affects her brain in a number of ways, for better or for worse. Estrogen, progesterone, and testosterone fluctuate during a woman’s menstrual cycle. The hippocampus, hypothalamus, and the amygdala tend to be affected the most by the estrogen-progesterone surges and drops. The surges of these hormones can influence a woman’s mood, self-esteem, and how she connects to others.

Understanding these fluctuations and their effects on the brain can help not only doctors but women comprehend why they feel the way they feel during their menstrual cycle.