Period Brain Fog: Your Menstrual Cycles and Cognitive Function

Do you feel like you have poor concentration during your period? Learn how shifting hormones during your monthly cycle can contribute to brain fog.

Rebecca Washuta
— Signos
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Reviewed by

Rebecca Washuta
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Updated by

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Science-based and reviewed

July 24, 2024
March 14, 2024
— Updated:

Table of Contents

Brain fog, or general cognitive difficulties, is something we’ve all dealt with at one time or another when we’re fatigued or stressed. However, women may be more prone to experiencing brain fog regularly, as hormonal changes throughout the month can have a direct impact on overall cognitive functioning. If you thought your menstrual cycle was only related to reproductive organs, think again. Shifting hormones affect everything from your mood, appetite, energy levels, and even your ability to focus. 

In this article, we’ll explore how the shifting sex hormones throughout your menstrual cycle may contribute to brain fog.


What Is a Menstrual Cycle?

The menstrual cycle is the series of physiological changes that happen in your body every month as your body prepares for the possibility of pregnancy. Your cycle begins the first day of your period and goes through the first day of your next period. It typically lasts about 28 days but can vary based on your age and weight.1 

What Are the Phases of the Menstrual Cycle?

woman shruken on the couch

Follicular Phase

This phase is considered the first part of your menstrual cycle. It starts on the day you get your period and runs through ovulation. Some experts break this down further into the menses phase and ovulatory phase.

Menses Phase 

The three to five days of menstrual bleeding occurs due to shedding of the lining of the uterus. Estrogen and progesterone are low during this phase, and follicle-stimulating hormone (FSH) starts to increase slightly. This causes follicles (each containing one egg) to develop in your ovaries. Prior to ovulation, estrogen levels begin to increase and hit their peak just before ovulation. 

Ovulatory Phase

Ovulation typically occurs about halfway through your cycle or 14 days before the start of your next period.2 During this time, your ovary releases the egg that has grown throughout the follicular phase. Luteinizing hormone (LH) and FSH rise sharply, progesterone begins to increase slowly, and estrogen levels decrease. 

Luteal Phase

This is considered the second half of your menstrual cycle and begins after ovulation. It’s referred to as the luteal phase because the follicle that released the egg turns into the corpus luteum, which produces progesterone. During this phase, progesterone and estrogen increase, creating a supportive environment in the uterus for an embryo. If you become pregnant, the uterine lining is maintained; if you don’t, the lining will be shed at the start of the next cycle. 

<p class="pro-tip"><strong>Also Read: </strong><a href="optimize-your-brain-health">How to Boost Your Brain Health</a>.</p>

How Fluctuating Hormones Affect Your Brain

It’s well known that sex hormones can impact your mood and emotional state. Some of the most common symptoms of premenstrual syndrome, or PMS, (which occurs towards the end of the luteal phase) are irritability, anxiety, depressed mood, and crying.3 What many people aren’t aware of, however, is that sex hormones also have an effect on emotion-independent areas of cognitive functioning, like concentration.4 Let’s take a look at how two of the primary sex hormones impact cognition. 

Estrogen and the Brain

One fMRI study showed that increased estrogen levels during the follicular phase boost activity in the hippocampus (an area of the brain responsible for learning, memory, and decision-making).5 It makes sense then that during your period when estrogen is at its lowest level, these types of tasks involving the hippocampus could be more difficult. 

Executive functioning, which refers to cognitive processes like monitoring, organizing, and planning, may also be impacted by hormone shifts. Research has shown that women with premenstrual dysphoric disorder, or PMDD (a severe form of PMS), have impaired executive functioning skills in the late luteal phase as estrogen declines (just before their periods).6

Estrogen receptors are found in multiple areas of the brain that are associated with learning, memory, and cognition, like the prefrontal cortex, dorsal striatum, and nucleus accumbens.7 Estrogen has specifically been found to impact dopamine-dependent cognitive processes, like selective attention and object recognition.7 Therefore, during the menstrual phase, when estrogen levels are low, activities requiring these processes may be more challenging. 

Progesterone and the Brain

Increased progesterone levels during the luteal phase (before the period begins) can impact sleep quality, resulting in fatigue and difficulty concentrating.6 Higher levels of progesterone are associated with improved verbal memory and visual memory tasks.8 This suggests that when progesterone drops just before your period, the performance of these types of tasks may be impaired. Progesterone has been shown to have neuroprotective effects by decreasing the loss of neuronal cells and accelerating repairs.9

Brain Fog and Your Cycle

doctor apparently having a conversation through a laptop

Despite the above findings, many factors outside of regular hormone shifts may contribute to brain fog. Things like inadequate sleep, poor nutrition, stress, and certain medications can all be to blame for cognitive difficulties. If you’re experiencing brain fog, it’s a good idea to work with a healthcare professional to evaluate all of these areas in addition to your hormones in order to identify the root cause. 

While evidence on period-specific brain fog is limited, it’s important to understand your cycle and listen to your body. Many women report they feel their best both mentally and physically just before and during the ovulatory phase and feel their worst just before and during the menses phase. If this is true for you, you may want to try to plan activities around your monthly cycle and opt to take it easy during the late luteal and menses phases. 

Learn How To Navigate Your Cycle With Signos' Expert Advice

Lifestyle changes are often the best way to prevent and reduce period weight gain and bloating. Cultivating better habits can help you stay healthy and balanced at that time of the month and throughout your cycle.

Signos can make it easier to make changes that will leave you feeling confident in your body and empowered in self-care. From educating yourself about the foods that provide lasting energy and stable blood sugar to how your body responds to stress and exercise, Signos gives you real-time feedback for whole-body health

Just getting started in your journey? You can learn more about nutrition and healthy habits on Signos' blog or find out if Signos is a good fit for you by taking a quick quiz here.

<p class="pro-tip"><strong>Learn More: </strong><a href="best-vitamins-for-women-over-50">What Vitamins Are Most Important for 50+ Women? Sources + Tips</a>.</p>

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About the author

Rebecca Washuta is a licensed dietitian with degrees in neuroscience and nutrition and helped individuals develop long-term health habits and achieve various wellness goals.

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Please note: The Signos team is committed to sharing insightful and actionable health articles that are backed by scientific research, supported by expert reviews, and vetted by experienced health editors. The Signos blog is not intended to diagnose, treat, cure or prevent any disease. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider. Read more about our editorial process and content philosophy here.

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