Brain fog: when your head feels full of cotton wool – iron, sleep, stress and gut

You read the same paragraph for the third time and still do not know what it says. In the middle of a conversation, a simple word escapes you, and on your way to the kitchen you have forgotten what you wanted there. Your head feels as if it is full of cotton wool. Sound familiar?

Many people call this state “brain fog”. This article explains what is meant by it, which causes can be behind it – from sleep and stress to iron and vitamin B12 to menopause – and what can be measured.

What actually is brain fog?

Brain fog is not a medical term and not a diagnosis. It is an umbrella term for symptoms that many people describe in a similar way: problems concentrating, slower thinking, forgetfulness, difficulty finding words and the feeling of not being quite all there mentally. Because so many different things can be behind it, it is worth looking not just for one cause, but for several building blocks.

Problems concentrating in adults: sleep is the first suspect

Even short-term lack of sleep has a measurable effect on thinking. A meta-analysis of 70 studies shows that sleep deprivation mainly impairs simple attention, but also working memory and processing speed (PubMed 20438143). If you sleep too little or badly for weeks, you will often notice it first as a problem with concentration.

The reason is not always obvious. In obstructive sleep apnoea, breathing stops briefly again and again during sleep, often together with loud snoring. The most common symptom is marked daytime sleepiness, but many people affected do not notice anything themselves (PubMed 32286648). It affects not only men but also many women (PubMed 32286648), and it is associated with effects on thinking ability (PubMed 31300334). If someone tells you that you stop breathing in your sleep or snore heavily, talk to your doctor about it.

Brain fog from stress: when your head is full

Constant tension, always being reachable and too few breaks are among the most common reasons why your head feels overloaded. Stress often works through sleep: if you cannot switch off in the evening, you sleep worse and are less focused the next day. Tiredness in general is also often linked to strain and psychosocial reasons in general practice (PubMed 27765009).

Depression and anxiety disorders can also show up as problems concentrating. If low mood, loss of joy or persistent worries come on top of the fog in your head, this belongs with your doctor.

Brain fog and iron deficiency: problems concentrating due to empty stores

Iron is needed not only for the red blood pigment, but also in the brain. An iron deficiency can cause symptoms even before anaemia develops, and it particularly affects women before menopause (PubMed 33285139).

In a placebo-controlled study of women aged 18 to 35, participants with iron deficiency performed worse in thinking tasks than women with good iron levels. Those whose ferritin improved markedly with iron also improved in the tasks (PubMed 17344500). This shows a link in women with a proven deficiency – it is not a reason to take iron on suspicion. Too much can be harmful.

Vitamin B12, thyroid and blood sugar

Vitamin B12 is important for blood formation and the nerves. A deficiency can lead to tiredness, anaemia and neurological symptoms, including problems with memory and concentration. Older people, people on a vegan diet and people who take certain medications are affected more often (PubMed 23301732).

Thyroid: In an underactive thyroid, tiredness and lack of drive are among the most common symptoms (PubMed 28336049). Many people affected also describe slowed thinking. The TSH level is a first indication.

Blood sugar: Some people experience strong fluctuations, for example after very sugary meals or during long breaks without food, as a dip in concentration. If you have diabetes or take medication that lowers blood sugar and suddenly become shaky, sweaty and unfocused, you should think of low blood sugar and discuss this with your doctor.

Brain fog in women: menopause, cycle and iron

Forgetfulness, “brain fog” and problems concentrating are among the common symptoms women experience during the transition to menopause (PubMed 27272226). A review by the International Menopause Society describes that thinking changes in many women during this phase, and stresses that professionals should take this experience seriously and help put it into context (PubMed 36178170). Sleep disturbed by hot flushes and night sweats can also play a role.

In women before menopause, iron is an additional topic: heavy periods contribute significantly to iron deficiency and are often accepted as “normal” (PubMed 36706856).

After an infection, due to medication – and the gut-brain axis

After viral infections, some people report problems concentrating for weeks. In a meta-analysis on COVID-19, around one in five of those examined showed cognitive impairment twelve weeks or more after diagnosis (PubMed 34973396). Options for diagnosing and treating long COVID are still considered inadequate (PubMed 36639608). The assessment belongs in the hands of a doctor.

Medication can also dampen thinking, for example some sleeping pills and sedatives or allergy medicines. A look at the package leaflet and a conversation with your doctor or pharmacist can help. Do not stop a prescribed medication without talking to your doctor first.

Brain fog and the gut: The gut and the brain are connected via nerves, the immune system and metabolic products of gut bacteria. This gut-brain axis is an exciting research topic. However, many findings so far come from animal studies, and studies in humans are still ongoing (PubMed 31460832). Whether and how the gut influences problems concentrating has therefore not yet been established.

Warning signs: when it is an emergency

Call the emergency number 112 immediately if sudden confusion, speech problems, vision problems, paralysis or a drooping corner of the mouth occur. These can be signs of a stroke, and every minute counts.

Have it checked by a doctor promptly if your forgetfulness increases over weeks, if other people mention it to you, if you can no longer find your way around familiar surroundings or if the fog in your head started after a fall or a head injury.

Measure instead of guess: which levels you can have tested

Whether iron, B12 or the thyroid are involved cannot be read from how you feel, but it can be measured. With ORY, you take a small blood sample at home for this:

• The OM Vital blood test measures, among other things, ferritin, the thyroid level TSH, the inflammation marker hs-CRP, vitamin B12, vitamin D and folic acid. A blood count is not included.
• The Basic vitamin check focuses on vitamin B12, folic acid, vitamin D, vitamin E and coenzyme Q10.

The results are building blocks, not a diagnosis. Take them with you to your next doctor’s appointment. The ORY expert team can also support you in a consultation to help put them into context.

In brief

• Brain fog is not a medical term but an umbrella term for problems with thinking and concentration.
• Lack of sleep has been shown to impair attention and working memory (PubMed 20438143).
• Iron deficiency, B12 deficiency and an underactive thyroid are known, measurable building blocks.
• Problems concentrating are common during menopause (PubMed 27272226).
• Sudden confusion, speech or vision problems and paralysis are an emergency: 112.

Frequently asked questions

Can iron deficiency cause brain fog?

Iron deficiency can affect concentration and thinking performance. In a study of young women, participants with iron deficiency performed worse in thinking tasks, and an improvement in ferritin was linked to better results (PubMed 17344500). Whether you have a deficiency is shown by measuring ferritin together with an inflammation marker.

What helps with problems concentrating caused by iron deficiency?

First the measurement, then the cause: where does the deficiency come from, for example heavy periods? Whether and how iron is supplemented is something you decide with your doctor or other professionals. Taking iron on suspicion is not a good idea (PubMed 33285139).

Can gut problems cause brain fog?

The gut and the brain are closely connected, and the gut-brain axis is being researched intensively. However, many results come from animal studies (PubMed 31460832). A proven link between the gut and brain fog in humans has not yet been established.

Can stress cause brain fog?

Yes, stress and overload are among the common reasons for problems concentrating, often through poorer sleep. If the state persists or low mood and loss of joy come on top, seek medical advice.

Why do women often get brain fog during menopause?

Forgetfulness and problems concentrating are common during the transition to menopause (PubMed 27272226). The hormonal changes and symptoms such as hot flushes and disturbed sleep are being discussed as reasons (PubMed 36178170). Raise it with your gynaecologist.

What causes brain fog and poor concentration in adults?

Common causes are lack of sleep, stress and overload. In addition, there are iron or B12 deficiency, an underactive thyroid, sleep apnoea, menopause, the time after infections and medication. A medical assessment helps to sort out the building blocks.

Sources

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