Brain fog: What it is, causes, symptoms & treatment

If you find yourself frequently losing your train of thought or unable to find the right words in regular conversation, it can be really unnerving and troubling. It’s possible that you might be suffering from brain fog, a common cognitive condition that affects more than 25% of adults [1]. 

What is brain fog?

Brain fog, which is sometimes also referred to as cognitive or mental fog, is a non-clinical term used for a really wide range of symptoms that all have to do with your ability to think, remember, and concentrate at your normal levels. While not a clinical diagnosis, brain fog can happen as a side effect of some medications, as a symptom of a medical condition, or even related to changes in your hormone levels. Brain fog is normally temporary and lasts as little as a couple hours or a few days, but can sometimes stick around for longer (think weeks, months, or even years) depending on its underlying cause [1].

What does brain fog feel like?

Brain fog can feel different for everyone. Some describe it as a feeling of deep mental fatigue or sluggishness. You might find you’re having trouble paying attention, thinking clearly, or making decisions. It can also sometimes feel like you are constantly losing your train of thought or having trouble finding the right words in conversation [1].  

Causes of brain fog

Right now, scientists don’t really know exactly what causes brain fog, but they do see it popping up in relation to a wide variety of different lifestyle, physical, and mental situations and conditions. Current research is leading scientists to believe that brain fog might be linked to inflammation, hormones, nutritional deficiencies, and/or the way electric pulses work with chemical signaling in your brain and nervous system [1]. 

Medically, certain autoimmune diseases, chronic conditions (like diabetes), and mental health conditions (like anxiety or depression) have been linked to brain fog [1]. There is also evidence of brain fog in the recovery period after treatments like chemotherapy [2] and following COVID-19 infections, which is sometimes referred to as long COVID [3].

As brain fog has been linked to hormones, this has particularly big implications for women, who undergo major hormonal changes as part of their reproductive lives. Because it’s common to experience brain fog in relation to your menstrual cycle, pregnancy, and perimenopause, let’s dig into each in a little more detail.

Brain fog and PMS

PMS, or premenstrual syndrome, is the general name for all symptoms you might experience in the weeks or days before you get your period. In addition to physical symptoms like breast tenderness, cramps, and headaches, they also include a number of mental and cognitive changes like mood swings, irritability, tiredness, anxiety, and sleep disruption [4].

The sex hormones estrogen, progesterone, and testosterone all play an important role in brain, behavior, and cognitive functioning. During the luteal phase, which is the second half of your cycle, estrogen levels fall and progesterone increases. Researchers believe that sensitivity to these hormonal changes — rather than the changes themselves — may contribute to PMS symptoms, including difficulties with concentration often described as brain fog [5].

One study of younger women experiencing brain fog related to hormonal changes or the pill also demonstrated a negative feedback loop, whereby the initial experience of brain fog led to more stress and anxiety, worsening existing brain fog symptoms. For researchers, this highlights just how detrimental brain fog can be to day-to-day life, and why it can be important for those experiencing brain fog to understand its causes and how to manage its symptoms [6]. 

Brain fog and pregnancy 

Brain fog during pregnancy is so common that it is often called pregnancy brain or mom brain. Similar to the menstrual cycle, pregnancy involves hormonal shifts (though on a much larger scale), including large increases in estrogen and progesterone. These hormonal changes are thought to affect how the brain works both during pregnancy and after birth [7].

Research suggests that this is more than simply a feeling of mental fuzziness. In one study, pregnant women in their second and third trimesters were compared with non-pregnant women across a range of cognitive tests. The pregnant group performed significantly worse on tasks related to verbal memory and language, including naming everyday objects [8]. The researchers proposed that these subtle cognitive changes may reflect a temporary trade-off: as the brain adapts during pregnancy, some resources may be redirected toward supporting the transition to motherhood [8].

This interpretation is supported by brain imaging studies showing that pregnancy is linked to measurable structural brain changes, especially reductions in gray matter [7]. Rather than indicating harm, these changes appear to be part of the brain’s natural adaptation process, reshaping regions involved in social cognition and emotional processing to help prepare for parenthood. Evidence also suggests that much of this brain tissue recovers after delivery, with substantial increases seen during the postpartum period [7].

[8]. 

Brain fog and perimenopause

During perimenopause — which is the period of transition before your final menstrual period, or menopause — brain fog can be one of the most disruptive symptoms alongside hot flashes, night sweats, sleep disturbances, and mood changes. Researchers think that fluctuating hormone levels — especially estrogen — may contribute to changes in cognition, sleep, mood, and behavior, although the evidence is not entirely consistent [9].

How long does brain fog usually last?

Brain fog can last for hours, days, or even longer, depending on the underlying cause. For example, if you experience brain fog as part of your menstrual cycle, it might go away when your PMS finally abates. Pregnancy brain, on the other hand, can last the duration of your pregnancy and even months postpartum [8]. Similarly, brain fog can persist throughout perimenopause, as hormone levels continue to fluctuate until and beyond reaching menopause [10].

Tips for tackling brain fog at home

Unfortunately, there are no specific treatments for brain fog, but there are certain day-to-day practices that you can try implementing to help relieve some of your symptoms. Physical activity and diet have both shown some success in treating brain fog conditions [1]. Making sure you get enough sleep and staying hydrated can also help [11]. While studies have shown that supplementing with certain vitamins and minerals can help with mental fatigue, it’s important to consult with your doctor before incorporating them into your routine [12].

When to talk to a doctor

If you are concerned about any cognitive disruptions you are experiencing, particularly if they are impacting your day-to-day life, it’s important to talk to your doctor. In most cases, brain fog is not considered a sign of a more significant health problem. That said, figuring out the cause of brain fog can sometimes be difficult. Your doctor can help assess whether brain fog might be tied to any medications you’re currently taking, and they might suggest specific treatments that could help alleviate your symptoms. 

Treatment options

In most cases, brain fog is temporary and goes away on its own. It’s important to remember that brain fog is not usually a signal of any long-term cognitive decline, and is very common for those going through a hormonal transition period, such as pregnancy, postpartum, or perimenopause. That said, it can be quite disruptive, particularly if you are experiencing it regularly or for more extended periods of time. You don’t have to suffer through it if it’s affecting your daily life — there are treatment options available.

For women going through perimenopause, some of the treatment options for symptoms like sleep disruption and hot flashes can also be used to help relieve brain fog. For example, hormone therapy (HT, also known as hormone replacement therapy or HRT) has been shown to improve symptoms like brain fog in some women. However, it's important to speak with your doctor as HT is not recommended for women with certain preexisting conditions or who belong to certain risk groups. Recent studies of estrogen receptor–targeted therapies suggest they may be among the next generation of treatments for perimenopausal women [10].

For those suffering from severe or long cases of brain fog, there are non-chemical or non-drug treatments that can help. For example, studies of patients suffering from long COVID–related cognitive symptoms have demonstrated some success with cognitive rehabilitation [13]. Cognitive rehab typically includes exercises and therapies designed to help you strengthen mental abilities or adopt new cognitive strategies [14]. 

Get to know your body better

Brain fog can occur at any stage of your life, whether it’s linked to PMS, pregnancy, perimenopause, or another health condition. If you’re interested in learning more about how the changes in your body might be affecting your mood and your memory, Natural Cycles can help. Five different modes — Birth Control, Plan Pregnancy, Follow Pregnancy, Postpartum, and Perimenopause — help you navigate your symptoms and find patterns, so you can feel more empowered through the process. You can even download a Cycle Report to share with your doctor, providing them with a clear record of your experience.