Hormones and Brain Fog: What Researchers Know About Women and Men

“Could it be my hormones?” is one of the most common questions people ask when they feel foggy, whether that shows up as asking someone to pass “the thing that changes channels” or something else, and it’s a fair one. Hormones do affect energy, mood and sleep. But “hormone imbalance” is also one of the most overused phrases online, often attached to long symptom lists and supplement pitches. This guide sorts out what researchers actually know about hormones and thinking in women and men, what’s still unclear, and which everyday habits are associated with steadier hormones.

If you’d like to hear how other people describe the foggy feeling first, see what brain fog feels like.

What “hormone imbalance” does and doesn’t mean

Cleveland Clinic describes a hormonal imbalance as having too much or too little of one or more hormones, your body’s chemical messengers, and calls it “a broad term that can represent many different hormone-related conditions.” In other words, it isn’t one diagnosis. It’s an umbrella over things like thyroid problems, diabetes, menopause-related changes and low testosterone, each of which has its own tests and its own story.

Cleveland Clinic also notes that certain hormone levels vary drastically through the day, which is one reason providers typically use blood tests, sometimes more than one kind, rather than guessing from symptoms. And because tiredness, mood changes and trouble concentrating show up with sleep loss, stress, illness and many other things, a symptom list alone can’t tell you which of these is going on.

Women: the menopause transition

The NHS lists “mood changes, poor memory and brain fog” among the symptoms of menopause and perimenopause, saying you may notice problems with your memory or concentration, and that these symptoms may feel worse if you also have sleep problems and feel very tired. That matches what many women describe.

Research on this is real but nuanced:

• A large, long-running study. The Study of Women’s Health Across the Nation followed 2,362 women for four years and tested processing speed, verbal memory and working memory. Women in late perimenopause did not show the improvement on repeat testing that other groups did, and delayed recall did not improve during early or late perimenopause. Scores rebounded in postmenopause, and the authors suggested that menopause transition-related cognitive difficulties “may be time-limited.”
• A smaller study with a different timing. In a cross-sectional study of 117 women, those in the first year after their final period performed worse than women in the late reproductive and late transition stages on verbal learning, verbal memory and motor function. The authors concluded that cognitive function does not change in a straight line across perimenopause and that decreases may be most evident in that first postmenopausal year.
• A pooled analysis. A systematic review and meta-analysis of four cross-sectional studies found postmenopausal women performing worse than pre- and perimenopausal women on delayed verbal memory tasks. The authors added that the results can’t necessarily be generalized beyond the studies included.

So the studies agree that something measurable can happen around this transition, but they disagree about exactly when, and they describe averages, not what any one person will experience. Some of these studies also look at hormone therapy, which is a prescribed treatment whose decisions belong in a conversation with a clinician; this page doesn’t recommend for or against it.

Other life stages matter too. See pregnancy, postpartum and brain fog and cycle-related brain fog. For the years around the change, see menopause, perimenopause and brain fog.

Thyroid

The thyroid is a small gland that helps set the pace of your body. The NHS lists difficulty concentrating or thinking clearly, feeling extremely tired, feeling cold more than usual, weight gain, low mood and dry skin among the common symptoms of an underactive thyroid, adds that symptoms usually develop slowly, and notes that some are common and can be caused by other conditions. It says a GP may arrange blood tests for thyroid-stimulating hormone (TSH) and thyroxine (T4).

There’s also a research literature on people who are already being treated for an underactive thyroid and still describe fog. A 2022 review in the journal Thyroid says that hypothyroid-associated brain fog has not been well defined or measured and that the underlying cause is unclear. It describes symptoms that commonly include fatigue, depressed mood and difficulties in memory and executive function, and that vary a great deal from person to person.

Men: testosterone

Mayo Clinic lists less sex drive, less energy and depression as early symptoms of male hypogonadism (the body not making enough testosterone), and says severe cases can bring trouble focusing. But many things look similar and are common in men, including short sleep, sleep apnea, weight gain and alcohol. We cover that in low testosterone and brain fog, including how testing works and what large studies have and haven’t found. For a plain walkthrough of the usual steps of an evaluation, there’s also an explainer on how testosterone evaluation usually works, published on a separate site that is focused on Montana.

Habits that are associated with hormone levels, and their limits

Cleveland Clinic lists general habits that it says could help keep hormones balanced: maintaining a healthy weight, eating a balanced diet, exercising regularly, managing stress, getting enough quality sleep, managing chronic health conditions and not smoking. It also says many hormonal imbalances aren’t preventable. Here’s what some studies add for men’s testosterone specifically:

• Sleep. In a small experiment with ten healthy young men, a week of five-hour nights was followed by daytime testosterone about 10% to 15% lower.
• Weight. A meta-analysis found that weight loss through a low-calorie diet or bariatric surgery was associated with higher testosterone in men with obesity.
• Alcohol. NIAAA’s journal reports that alcohol use is associated with low testosterone and altered levels of other reproductive hormones in men.
• Exercise. This one is less clear. A meta-analysis of randomized trials in insufficiently active, otherwise healthy men found that exercise training had a negligible effect on resting testosterone. So we’d pick exercise for its own sake, as a small, repeatable habit, rather than as a hormone fix.

On supplements, Cleveland Clinic says many nutritional supplements in stores claim to treat hormonal imbalances but few have been scientifically proven to have a beneficial effect. We aren’t recommending any.

When it’s worth getting checked

Because “hormones” covers so many different conditions, the practical path is boring but reliable: bring a clear picture of your symptoms and timing to a clinician and let blood tests narrow things down. Cleveland Clinic says that if you have new, persistent symptoms it’s important to talk with a healthcare provider, who can order tests. A few notes that may help the conversation:

• When did the fog start, and did anything change then, such as sleep, a new medicine, weight, a life event or your cycle?
• What else comes with it: heat or cold sensitivity, changes to periods, hot flushes, low libido, mood changes?
• What have you already tried, and did anything shift it?

A short symptom diary is a good way to collect this.

Small first steps

You don’t need to fix everything. Pick one.

• Look at sleep first. Choose a consistent wake time for a week. Many hormone-related symptoms overlap with short sleep, so this is a useful first check. See how to sleep better.
• One alcohol-free night. Swap one evening’s drink for something else and note how you feel the next day.
• Add a short walk. Fifteen minutes after a meal, for its own sake.
• Make a one-page timeline. Write when symptoms started, what changed around then, and what makes them better or worse.
• Go easy on hormone-balance products. Cleveland Clinic says few have been scientifically proven to help, so the basics above, and a proper check if symptoms persist, are a better place to start.