Period Brain Fog: Why am I feeling Foggy during Periods?

Brain fog is often a typical symptom of premenstrual syndrome. Hormones play a huge part in brain fog, and an imbalance in your sex hormones could potentially give rise to forgetfulness and feeling foggy around the time of your period.

Estrogen and progesterone both decrease in the days leading up to your period. The effects of this are thought to be of particular importance for other hormones and neurotransmitters. Estrogen is a primary hormone in the menstrual cycle of a woman. It can help optimize the production of neurotransmitters and the brain function when the estrogen levels are healthy and balanced. This is associated with lower serotonin levels and higher stress hormone cortisol levels which both can influence your mood and alertness.

Too little estrogen can cause depression and confusion. The loss of estrogen is also an obstacle to critical thinking, short memory and other cognitive tasks. These problems can get worse when the estrogen levels are wildly fluctuating and when the hormone drops and remains low during a menopause.

Progesterone calms you, brings you peace and encourages sleep when it is balanced with estrogen. But calmness can give way to irritation, anxiety, depression, sleepless nights and brain fog when they are imbalanced or when the relaxation hormone falls too dramatically. For some women, mood stability goes out of the window when progesterone and estrogen fall just before menstruation begins.

You are also at a greater risk of anemia if you have more severe periods. Anemia can lead to low iron, which is essential to the body's carrying of oxygen. Even somewhat lower oxygen levels into the brain can lead to a fog and you can feel a little lenient and forgotten.

Can periods cause brain fog?

Period pain has sometimes been linked with brain fog. 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. 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. 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.

Do you feel brain fog before or during periods?

Women experience PMS symptoms before the start of their period, referred to as the luteal phase. This is caused by the increased levels of progesterone. Cortisol, the 'stress hormone,' also uses progesterone to make women more irritable, depressed and anxious. Depleted serotonin (due to higher levels of cortisol) can lead to a lack of alertness.

Progesterone and estrogen levels are lower on day 1 of the menstrual cycle. Women can feel unmotivated and fatigued. This may also be associated with feeling cramps that contract your uterus muscles to push your blood out.

But the estrogen levels rise about a week in your cycle. Estrogen promotes endorphin ("feel good" hormones) release and suppresses cortisol and adrenaline stress hormones. As a result, the brain fog should dissipate leading to feelings of happiness, and being alert and energetic.

Do you have PMS brain fog?

Some women experience this mental fuzziness with every menstrual cycle. This is common especially before the start of the period is when women experience PMS symptoms because estrogen and progesterone levels both fall. This often results in brain fog. But about a week into your cycle, you should be back to feeling normal. Estrogen levels rise during this period. As a result, the brain fog and moodiness that you may feel before and during your period should dissipate and you’ll be more happy, alert, energetic, and motivated. If that's not the case then there might be other underlying reasons causing it.

How to get rid of it?

  1. Rest & Sleep: During your premenstrual week, you’re getting worse sleep as low levels of estrogen reduce sleep-regulating serotonin in the brain and makes you more sensitive to smells, sounds, light and anything else that can keep you awake. This impacts your mental and physical energy. You will need to find ways to get relaxed and get a good night’s sleep. To relax, you can try yoga, meditation, melatonin, or chamomile tea to ensure you get a good night’s rest.

  2. Tackle anemia: As you lose a lot of blood during periods, especially due to heavy periods, you may have anemia due to the iron you are losing. Anemia symptoms can appear to be more severe during your period. Vegetarians are particularly prone because most people get iron from animal products. Your doctor can check your levels with a quick blood test, and if you're anemic, they’ll likely prescribe supplements. It's also a good idea to add more iron-rich foods, such as red meat, leafy greens, egg yolks and beans, to your plate.

  3. Drink green tea: It has a far smaller amount of caffeine in it than black tea and coffee–and this is actually a good thing since too much caffeine in your premenstrual week can worsen irritability and moodiness. However, it has just enough caffeine to give you a mild boost, plus it has l-theanine, which is calming (but in a way that’s not tiring) and helps you focus. Green tea is also rich in certain compounds called catechins–the most recognized one is EGCG–that sharpen memory and boost concentration.

  4. Eat dark chocolate: Dark chocolate contains compounds that have mood-boosting effects in the brain, including endorphins and serotonin. These chemicals are necessary for mood enhancement and feeling good! Chocolate also improves blood flow to the brain, helping with focus and memory.

  5. Exercise: Exercise has proven to increase serotonin levels (good feelings), and decrease cortisol (stress). Therefore, activities that pump your blood, such as running, cycling, lifting weights, or HIIT will work in increasing blood flow to the brain. This blood flow will in turn reduce the brain fog you’re experiencing.


Brain fog during periods, especially before the period is a byproduct of the pain and the hormone imbalance in women. As we see above, it is common for many women to experience brain fog during periods. There are natural ways (check out some more natural remedies to cure brain fog) to combat this through sleep, making sure there isn’t too much iron deficiency, and keeping active.

  1. Tu CH, Niddam DM, Chao HT, et al. Brain morphological changes associated with cyclic menstrual pain. Pain. 2010;150(3):462-468. doi:10.1016/j.pain.2010.05.026
Back to blog