Brain fog can result from a variety of different hidden causes. After helping over 1,000 clients with brain fog and healing my own, I’ve figured out the causes and the most effective solutions. You can also take the quiz at the end of this post to find out what causes your brain fog. Read on to learn more about brain fog and how you can also find the solution to getting rid of it.

What Is Brain Fog?

Brain fog is a collection of symptoms such as forgetfulness, lack of mental clarity, confusion, and inability to focus. It’s not a clinical term and is also referred to as ‘mental fog,’ ‘clouding of consciousness,’ or ‘cognitive dysfunction.’

It is generally caused by inflammation in the brain, stemming from some underlying cause.

Symptoms

Fatigue and low energy (including chronic fatigue syndrome)

Irritability

Inability to concentrate

Poor working memory and executive function

Poor ability to memorize things

Impaired ability to process new information and delayed processing

Confusion

Low motivation

Mental confusion

Wandering thoughts; inability to sustain a train of thought

Disorientation

How Long Does Brain Fog Last?

Depending on the causes, brain fog can last anywhere from a few minutes to decades if untreated.

In most cases, brain fog is reversible.

Brain fog or ‘mental fog’ stands for reversible cognitive impairment caused by inflammation in the brain. Symptoms include forgetfulness, confusion, irritability, low motivation, and fatigue.

My Brain Fog Cure Story:

I’ve suffered from brain fog as long as I can remember. Brain fog is what got me interested in health at an early age. At 12, I endeavored to stop eating any food with sugar and ate only whole grains.

I’ve always tried to eat as healthy as possible, yet I still had brain fog. I would always read about health when I got the chance, but nothing helped that much.

After many years of experimentation and research, I finally figured out what caused my brain fog and how to heal it. After having over 1,000 clients with brain fog (as of March 2018), I’ve identified the most common causes of brain fog and have helped others heal their condition as well.

Brain Fog Causes

An Imbalanced Limbic System

Brain fog is essentially caused by an issue in the area of the brain responsible for executive function, general cognitive function, and emotional balance. This area is called the limbic system. Within the limbic system, the hypothalamus – also known as the ‘control center’ – is most affected.

The limbic system is responsible for:

Wakefulness (increases)

Appetite (increases)

Mood

Motivation (increases)

Body warmth (increases)

Gut flow by way of the vagus nerve (increases)

Metabolism (increases)

Blood pressure (increases)

Emotional regulation

Executive function

Memory – short and long-term

Brain fog can be caused by the limbic system disbalance, usually as a result of an injury or highly stressful event. A big bout of inflammation, free radicals, or emotional stress are the mechanisms by which these brain changes occur.

The hypothalamus, in particular, plays a critical role in the following [1, 2]:

Thermal regulation

Sweating

Wakefulness/fatigue

Circadian rhythms (regulates sleep-wake cycle)

Thirst

Hunger, satiety

Blood pressure, heart rate

Gut function

Emotions

Sex drive and hormones

Glucose regulation

Vision

Brain fog usually occurs due to an imbalanced limbic system, which affects cognition and emotional balance. Injuries and chronic stress can damage the hypothalamus, which is the ‘control center’ of the limbic system.

Symptoms of Limbic System Problems

The limbic system is responsible for many things, so if you’re having brain fog, it will often go together with other symptoms, such as:

Fatigue

Anxiety

Depression

Insomnia

Circadian rhythm issues – tired in the day, awake at night

– tired in the day, awake at night Lower motivation

Suppressed appetite and often weight loss

Memory problems

Cold hands and feet , problems with temperature regulation

, Gut problems , including constipation

, Lower thyroid and sex hormones

Overstimulated HPA axis

Lower blood pressure

Frequent urination

Procrastination – Overambitious, but not enough motivation to implement the ambition

– Overambitious, but not enough motivation to implement the ambition OCD / problems letting go of thoughts

/ Hypoglycemia

Attention problems

Hormonal issues

Lower libido and sex drive

Pain

Visual problems

Due to the complex functions of the limbic system, brain fog often goes together with mood, sleep, hormonal, and metabolic disorders.

Inflammation and Free Radicals

Brain fog/cognitive dysfunction comes from inflammation, and too many free radicals (oxidative stress) [3, 4].

Inflammation and oxidative stress affect the limbic system and can cause it to be imbalanced.

In 2014, 2 studies found that the gene expression of the antioxidant SOD2 (MnSOD) strongly correlated with cognitive performance [4, 5].

The main SOD2 variant rs4880 GG is more common in my brain fog clientele, and there’s a lot of scientific research on it.

A study found that the expression of another antioxidative enzyme gene that breaks down H2O2 (MPO/Myeloperoxidase) was also strongly tied to cognitive performance. Having a mutation in these genes could result in cognitive impairment [6].

Another trial found that mutations in genes that code for melatonin (ASMT) – an internal antioxidant hormone – were tied to cognitive impairment [7].

Inflammation and oxidative stress can damage the limbic system and cause brain fog. Gene mutations that reduce the activity of antioxidant enzymes might make people more susceptible to brain fog.

Conditions Associated with Brain Fog

Being heavily associated with oxidative stress and inflammation, brain fog is much more likely to occur in conjunction with other conditions.

There’s evidence that chronic fatigue syndrome (CFS) and fibromyalgia are caused by oxidative stress and inflammation [8, 9, 10, 11, 12, 13, 14, 15, 16].

Inflammation hits the brain stem as well in CFS [17].

It’s no wonder that brain fog is commonly cited in people with chronic fatigue syndrome and fibromyalgia – the same processes are driving all three.

Mood disorders such as anxiety, OCD, depression, schizophrenia, bipolar, and alcoholism can exacerbate brain fog because oxidative stress plays a role in these disorders [18, 19, 20].

In fact, science is discovering now that many antidepressants work by combating oxidative stress [20].

I’ve noticed a strong correlation with these disorders – especially OCD, anxiety, and depression- and brain fog in my clients. I had all three when I used to have brain fog.

In multiple sclerosis, Sjogren’s, and lupus, brain fog is a common feature. In all of these disorders, inflammation and oxidative stress are increased.

Female hormones such as estrogen and estradiol tend to display antioxidant activities and lower oxidative stress, which is why women with menopause sometimes develop brain fog.

Brain fog often goes hand in hand with other conditions caused by inflammation and oxidative stress. Its connection with mental and autoimmune disorders is particularly strong.

The Most Common Brain Fog Triggers

I’ve had clients with brain fog from all of the following causes. I’ve ordered them from most common to least common. These can cause brain fog either by causing inflammation or by causing long-term changes in the brain.

Various factors can trigger brain fog. From my experience with clients, the most common ones are lectins (pro-inflammatory diet), anxiety, and stress.

1) Diet

There are many other possible sources for brain fog. However, I’ve only listed the most common ones that wouldn’t be diagnosed by your doctor.

If you get brain fog after eating, then you must look more carefully at your diet.

Brain Fog After Eating

The most common causes of brain fog are lectin and food sensitivities. When people consume food that causes inflammation, it will often cause brain fog.

People with lectin sensitivity will most often experience inflammation in their gut, joints, thyroid, and brain (hypothalamus). Sometimes they’ll go on to develop an autoimmune condition eventually.

In some cases, people only have to stay away from specific proteins or foods and they’re fine.

However, lectins are not the only problem in food.

Some common triggers of inflammation are:

Lectins (every food has lectins, but we can be sensitive to different lectins)

(every food has lectins, but we can be sensitive to different lectins) Gluten (wheat, spelt, rye, barley, and oats)

(wheat, spelt, rye, barley, and oats) Casein (all dairy products)

(all dairy products) FODMAPs (short-chain carbohydrates that are often poorly absorbed by the small intestine)

(short-chain carbohydrates that are often poorly absorbed by the small intestine) Amines

Tannins

Trypsin inhibitors

Oxalates

Yeast (in gluten-free bread)

(in gluten-free bread) Food additives like carrageenan (in rice milk, almond milk, etc.)

like carrageenan (in rice milk, almond milk, etc.) Salicylates

Caffeine

You can be allergic to any other food as well. Egg and fish allergies are quite common, so pay attention to them.

Read this post on 19 antinutrients in plant-based foods that can cause inflammation.

Fix:

You should try out the strict version of the Lectin Avoidance Diet, which has helped a lot of clients with brain fog.

In some cases, brain fog can simply come from a horrible diet. High glucose levels can cause a threefold increase in free radicals, which can damage human cells [21].

If you’re living on a Standard American Diet, then that is likely a significant contributing factor to your brain fog.

Check out these markers for lectin sensitivity and listen to my interview with Dr. Gundry.

Lectins, food sensitivities, and pro-inflammatory nutrients are the primary dietary causes of brain fog. The Lectin Avoidance Diet helped most of my clients, and it should be your 1st step to overcoming brain fog.

2) Sleep

Not sleeping well is another common cause of brain fog.

If you have sleep apnea, that will most likely be the cause of your brain fog. Sleep apnea causes hypoxia (lack of oxygen) at night, which increases oxidative stress [22].

Hypoxia drives psychiatric conditions by causing neurons to get overexcited (glutamate excitotoxicity). This excitation causes increased levels of free radicals and mitochondrial breakdown.

Even if you don’t have sleep apnea, bad sleep is still a significant cause of brain fog but may not be the whole story.

Sleep loss increases oxidative stress in the hypothalamus, by the loss of glutathione [23].

Sleep deprivation for even one night exacerbates brain fog by increasing inflammation in the hypothalamus and the rest of the body [24, 25].

People with morning brain fog should particularly watch out for this. Adequate sleep in my book means getting the amount of sleep you’d get if you didn’t have an alarm clock.

Fix:

I suggest doing a sleep study and checking how much slow-wave and REM sleep you’re getting.

See my post on how to improve your sleep.

Poor sleep quality and disorders such as sleep apnea may cause brain fog by increasing oxidative stress.

3) Infections

Science is increasingly becoming aware of the link between autoimmune conditions and infections – usually earlier in life.

When someone was healthy their whole life and suddenly comes down with brain fog after infection, they should identify and get rid of the infection. In the case of viral infections, you should take steps to control it.

Infections can cause chronic inflammation and oxidative stress, leading to brain fog.

a) Viruses

Sometimes, infections such as viruses can be latent and then be reactivated by some stressor (lack of sleep, poor diet, etc.)

People with Th2 dominance often can’t control viral infections well and experience chronic inflammation. This is likely the case with chronic fatigue syndrome.

The Epstein-Barr Virus is a common viral infection that causes harm. Even if it’s another virus, controlling viral infections have common themes.

People with severe immunodeficiency struggle with controlling viral infections.

Since you can’t rid yourself of a virus, you want to instead make sure your immune system always keeps it at bay.

Fix:

If you’re Th2-dominant, then you want to rebalance your immune system.

Chronic viral infections may lurk behind brain fog. Make sure to rebalance your immune system, especially if you are Th2-dominant.

b) Bacteria

I’ve seen cases where brain fog was caused by a bacterial infection.

If you can identify a bacterial infection, then targeted drugs such as antibiotics would be a better option than herbs.

Gram-negative bacteria can also cause overproduction of inflammatory cytokines (TNF, IL-1, and IL-6) [26].

Only gram-negative bacteria have inflammatory lipopolysaccharides (LPS).

Some common infections include Lyme, Mycoplasma pneumoniae and H Pylori.

Bacterial infections such as Lyme, pneumonia, and H. pylori can cause inflammation and contribute to brain fog. Make sure to identify and get rid of any bacterial infections.

c) Fungi

I’ve seen other cases where candida or fungal infections were the sources of the brain fog.

Candida comes from an immune deficiency. Environmental triggers include refined carbs, stress, low stomach acidity (could be from antacids), and antibiotics.

Anybody with brain fog after antibiotic treatment and/or a particularly stressful period should look into candida as being the cause.

People with candida or bacterial infections will often have a chronic type of brain fog. Candida increases TNF, IL-1, and IL-6 [27, 27].

Candida and bacterial infections can usually be cured through conventional and alternative means.

Fungal infections such as candida stem from immune deficiency, poor diet, antibiotic treatment, and stress. Candida increases inflammation, and it’s a possible cause of chronic brain fog.

d-e) Parasites and Protozoa

Although less common in the developed world, parasitic infections can also be problematic.

Blastocystis hominis, tapeworm, roundworm antibodies, tissue worm, and Toxoplasma are common parasitic infections.

4) Heavy Metals, Toxins, Mold

Any kind of toxins can stimulate the immune system and cause inflammation and oxidative stress.

Heavy metals and toxins increase oxidative stress in the body. Since heavy metals accumulate in the body, they may cause increased levels of oxidative stress in the body.

Even essential minerals can accumulate in the body and cause oxidative stress in the long term.

Toxins such as phthalates and BPA pesticides and others also cause oxidative stress. However, these are usually contributory in a minor way.

People exposed to mold or other biotoxins can suffer from Chronic Inflammatory Response Syndrome (CIRS) and develop a certain kind of brain fog.

These inflammatory markers will often be elevated if exposed to toxins:

I discuss mold-induced illness and what to do about it in this post.

Exposure to heavy metals, environmental toxins, and mold can contribute to brain fog by causing inflammation and free-radical damage.

5) Low Acetylcholine

Symptoms of chronic inflammation and brain fog (often from chronic infections) sometimes match the symptoms from drugs that inhibit acetylcholine.

People with toxin issues will often fit into this boat, too.

Acetylcholine inhibits inflammation/cytokines and modulates the immune response. In turn, cytokines (TGF-b, IL-1, IL-17) can decrease acetylcholine [28, 29, 30, 28].

Fix:

Acetylcholine enhances cognition and reduces brain inflammation. Low acetylcholine levels may cause symptoms that resemble brain fog.

6) Insulin Resistance and Hypoglycemia

People with brain fog often get hypoglycemic (low blood sugar) because the limbic system helps control blood glucose. Hypoglycemia can, in turn, contribute to brain fog.

People with insulin resistance experience significant blood glucose fluctuations, which is even worse than sustained high or low levels of glucose [31].

These swings in blood glucose levels result in oxidative stress and inflammation and may thus cause brain fog [32, 33].

Fix:

Read my post on how to fix insulin resistance and what causes insulin resistance in the first place.

High or low blood glucose, as well as glucose fluctuations due to insulin resistance, result in oxidative stress and contribute to brain fog.

7) Hormonal Imbalance

The following hormones act as antioxidants by inhibiting superoxide (and other free radicals) [34, 35, 36, 37, 38, 39]:

Hence, their deficiency can contribute to brain fog. All of these listed hormones are anti-inflammatory as well.

Genes that resulted in lower melatonin, for example, are associated with cognitive dysfunction [40].

Brain injuries from car accidents, being in the military, being a competitive athlete, fighting (professionally or not), or any kind of hit to the brain can lead to low hormones. If you’ve received head blows from any source, you should check your hormones.

Fix:

Pregnenolone

I believe the fundamental causes of low hormones are chronic inflammation, circadian imbalances, sleep problems, or chronic stress.

Brain Fog and the Thyroid

With regard to thyroid hormones, low or high thyroid hormones can cause oxidative stress [41].

People with brain fog often have low levels of thyroid hormones. However, low thyroid hormones area result of inflammation, not the cause of it. In fact, having a high level of thyroid hormones increases inflammation. [42, 43, 44].

Melatonin, sex hormones, and oxytocin protect you against oxidative stress, while low levels increase the risk of brain fog. When it comes to thyroid hormones, both high and low levels can be an issue.

8) Leaky Gut and Dysbiosis

Intestinal permeability or “leaky gut” and an imbalance of your gut microbiota (“gut dysbiosis”) can increase inflammation, thereby contributing to brain fog.

Lectins are the most common reason for having a leaky gut, in my opinion.

To prevent microbial imbalance or dysbiosis, the gut needs the right ingredients, such as prebiotics, to work well.

Probiotics can also be great at silencing inflammation.

I’ve noticed that many people with brain fog also have IBS (including my former self). This is because inflammation of the gut contributes to IBS [8].

Fix:

Hi-maize/resistant starch

Consuming leafy greens

Probiotics

Gut microbiome imbalances and inflammatory components such as lectins contribute to leaky gut and brain fog. Improve your gut health by avoiding lectins and consuming probiotics, resistant starch, and fiber-rich veggies.

9) Allergies and Histamine

People with asthma and allergies commonly report brain fog, which is in part from the production of histamine.

Allergies and asthma can be a result of Th2 dominance.

Histamine can be produced from lectins or allergic reactions, as a result of an elevated Th2 immune system.

People can also consume foods with histamine – mainly fermented and cured foods and beverages.

If you don’t have enough of an enzyme to break histamine down, this can be the cause of your brain fog. I’ve found this to be the case for some people.

Oxidative stress may be the mechanism by which histamine causes brain fog [45].

Also, when mast cells activate, they release superoxide, which supports my central theory of brain fog (that superoxide is responsible) [46].

Fix:

Read my post on reducing histamine. Also, read my post on reducing Th2 dominance.

Allergic reactions, lectins, and certain foods can elevate histamine, especially in Th2-dominant people. High histamine may cause brain fog by triggering oxidative damage.

10) Anxiety, Chronic Stress, and Depression

In almost all cases of brain fog, people experience anxiety and often depression/bad moods.

This is mainly because inflammation increases our stress response and causes anxiety, which also leads to depression. This certainly happened to me.

Indeed, that’s why cognitive dysfunction, depression, and anxiety often go together (also because they’re all influenced by the limbic system) [47].

Inflammation (TNF, IL-1) and oxidative stress activate the stress pathway and cause us to be more anxious and depressed. Cytokines also degrade the hippocampus and other areas of the brain, which causes depression [48, 49, 50].

In turn, chronic stress can elevate inflammation in the long run (by causing glucocorticoid resistance) [51].

Fix:

Read my post on why stress is bad and my post on Corticotropin-Releasing Hormone (CRH).

Anxiety, chronic stress, and depression go hand in hand with brain fog. Brain inflammation and limbic system imbalances lurk behind all of these conditions.

11) Drugs

There are many drugs that can cause or contribute to brain fog.

Alcohol is a neurotoxin and increases inflammation and oxidative stress [52, 53, 19].

If you’re an alcoholic, that will most likely be the cause of your brain fog.

I’ve seen brain fog induced by alcohol, marijuana, LSD, MDMA, cocaine, and ayahuasca. The mechanism is almost certainly related to limbic system dysregulation.

I’ve also seen brain fog induced by antibiotics, which can produce free radicals and damage your mitochondria and the gut microbiome [54].

The following antibiotics induce free radical production: ciprofloxacin (a fluoroquinolone), ampicillin (a β-lactam), and kanamycin (an aminoglycoside).

Alcohol, antibiotics, and other drugs can cause brain fog by disturbing the gut microbiome and increasing oxidative stress and inflammation.

12) Genetics

There are a whole bunch of genes that don’t interact with our current environment well.

Three significant ones are CNR1, MTHFR, and SOD2 mutations. There are many others, but that’s beyond the scope of this post.

The CNR1 variation can cause a lot of problems with the limbic system and your gut.

Having the MTHFR mutation can hamper your ability to ‘detox’ and result in inflammation and oxidative stress.

The SOD2 mutation causes a 33% decrease of the enzyme (MnSOD) that breaks down superoxide in the mitochondria. Superoxide production can cause brain fog.

Obviously, your genes are only a part of the story. It’s usually the case that you need to have these mutations and other factors that increase oxidative stress.

The good news is that you can overcome genes with lifestyle and supplement choices, with the help of SelfDecode.

Mutations in genes such as MTHFR, CNR1, and SOD2 can contribute to brain fog, in combination with other factors. SelfDecode can help you adapt your lifestyle and supplement regimen to your genes.

Other Factors

The following are biological factors that contribute to brain fog or make it worse:

Adrenal Fatigue

The Limbic system/hypothalamus directs the adrenal glands. Adrenal fatigue is a misconception and the root cause of fatigue has to do with the hypothalamus, not your adrenal glands.

Derealization/Depersonalization

People who have strong levels of depersonalization and derealization have a bit of a different category of brain fog.

See my post on the biology of depersonalization and its potential solutions.

EDS, G6PD, Thalassemia, Anemia, and Gilbert’s Syndrome

Some conditions like Glucose-6-phosphate dehydrogenase (G6PD) deficiency and Thalassemia increase the risk of brain fog for somewhat different reasons.

G6PD deficiency results in higher levels of oxidative stress because of low glutathione.

Thalassemia results in lower red blood cells and hemoglobin, which means less transport of oxygen. This increases the risk of hypoxia in various tissues.

Anemia will also increase the risk of brain fog for the same reason: increased risk of hypoxia in various tissues.

Gilbert’s Syndrome is associated with brain fog possibly because it’s often caused by low glucuronidation, which limits the ability to detox.

Euler’s Danlos Syndrome (EDS) is associated with brain fog because of its effects on collagen formation, which affects many systems in the body.

Many conditions can contribute to brain fog by increasing oxidative stress, depriving the brain of oxygen, and disrupting detox mechanisms.

Brain Fog Treatments, Fixes, and Cures

1) Get Sunlight and Fresh Air

Sun is great for decreasing inflammation. Although uncommon, I’ve had a few cases of brain fog that were relieved simply by being outside and getting more sun.

Sun is capable of suppressing inflammation and preventing autoimmune disease [55, 56, 57].

Besides UVB rays directly suppressing autoimmunity, vitamin D also decreases Th1 and Th17 immune responses. The sun makes sulfated vitamin D, which is better than supplemental vitamin D.

Additionally, UVB increases our body’s internal antioxidant defenses [58].

People think that taking a vitamin D supplement will make up for not getting sun. This is false. In my opinion, most benefits of the sun don’t involve vitamin D.

The most beneficial “ingredient” of the sun is probably not vitamin D, but the infrared that it provides.

I recommend an hour of sun on most of your body (don’t exceed an hour for any spot).

If you can’t get sun, then use an infrared sauna and low-level laser therapy (LLLT).

Spending more time outdoors and getting more sun will strengthen your immune system, lower oxidative stress, and reduce brain fog.

2) Take Care of Your Sleep and Circadian Rhythm

The circadian rhythm is deeply connected with inflammation and both can cause the other to get out of balance.

I explore this subject in my post about why we get tired even with enough sleep.

Circadian disruption increases inflammation (Th1 and Th17) [59, 60].

The circadian rhythm is also tied to oxidative stress [61].

Disrupting your circadian rhythm will result in brain fog, as happens during jet lag. Some people are more sensitive to circadian disruptions. It can come about for a variety of reasons, but the most common are:

Lack of light during the day

Too much light at night

Disrupted sleep patterns

Chronic inflammation

Disrupting circadian rhythms can also lead to heart diseases, neurodegenerative conditions, and cancer [61].

People with brain fog are often wired but tired at night, fatigued in the day, and lack a cortisol spike in the AM. They can be hot at night and wake up to pee multiple times.

These are all symptoms of circadian disruption I used to have.

Now I get tired at night and am awake in the day. I feel warmer in the day and cooler at night and don’t get hypoglycemic at night. My vasopressin release has normalized so I don’t wake up to pee. I wake up refreshed and ready to hit the day when my circadian rhythm is working properly.

Read my post on how to take care of your circadian rhythm.

Circadian rhythm disruption and poor sleep quality increase inflammation and contribute to a range of health conditions, including brain fog.

3) Exercise

Too much or too little exercise can contribute to inflammation and oxidative stress.

I’ve never had a client whose brain fog was solely related to exercise, but it can be a contributory factor.

Moderate exercise brings down inflammation and oxidative stress. Interval exercise is particularly good.

Yoga is also particularly good because it balances the HPA axis. On the other hand, endurance exercise increases inflammation (Th17 immune response) [62].

Don’t confuse endurance exercise with moderate aerobic exercise. Although not as good as interval exercise or yoga, aerobic exercise can decrease inflammation as well [63].

Recommendations: Push-ups, yoga, pull-ups, walking, and sprints. Short sprints running as quickly as possible for 30 seconds make me feel really good, yet not worn out after 3 sets.

Yoga, aerobic exercise, and interval exercise in moderation help reduce inflammation and brain fog. On the other hand, high-intensity endurance exercise may make things worse.

4) Stimulate the Vagus Nerve

One common theme with people who have brain fog and chronic fatigue is lower vagal tone or vagus nerve activation.

Vagus nerve activation relaxes you by decreasing norepinephrine and inflammation while increasing GABA and acetylcholine.

Removal of the vagus nerve or desensitizing it with capsaicin increased brain oxidative stress and decreased glutathione following a stressor [64].

Vagus nerve stimulation decreased ROS/free radicals in response to stressors such as stroke (via AMPK) [65].

See my post on the vagus nerve and ways to stimulate it.

People with brain fog often have low vagus nerve activity. Vagus nerve stimulation increases brain antioxidants and reduces brain fog.

Supplements and Vitamins

These supplements get rid of inflammation and oxidative stress and help the limbic system.