Brain fog

Covers common causes of brain fog in men—like poor sleep, stress, low testosterone, nutrient deficiencies, inflammation, and medications—and how to identify the real driver. Learn evidence-based strategies to improve mental clarity, focus, and daily performance through training, nutrition, lifestyle, and targeted labs or TRT when appropriate.

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The essentials for brain fog — then explore the latest posts below.

Got “Normal” testosterone on Function Health but still feel off? How to interpret results and plan next steps.

Got “Normal” testosterone on Function Health but still feel off? How to interpret results and plan next steps.

Dr. Susan Carter, MD avatar
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Feb 09, 2026 · 11 min read

A testosterone result can be “normal” and still feel off because testosterone deficiency is diagnosed by symptoms plus consistently low morning total testosterone on repeat testing (often around ~300 ng/dL), and total testosterone can look adequate while free testosterone is low when SHBG is elevated. Here’s how to decide when a repeat draw matters, which ...

Brain fog in men: The best vitamins for brain fog and memory and the supplements that actually make sense

Brain fog in men: The best vitamins for brain fog and memory and the supplements that actually make sense

Dr. Jonathan Pierce, PhD avatar
Dr. Jonathan Pierce, PhD: Clinical Psychologist & Neuroscience Specialist
Jan 20, 2026 · 12 min read

The most evidence-based vitamins for brain fog and memory in men are B12 (often alongside folate and B6) to correct deficiency and reduce homocysteine, plus vitamin D when status is low, because these pathways support brain energy metabolism, neurotransmitter function, and immune-driven inflammation control. Here’s how to tell when “brain fog” is a fixable signal ...

Seasonal affective disorder or hormones? A men’s guide to winter mood, testosterone, and sleep

Seasonal affective disorder or hormones? A men’s guide to winter mood, testosterone, and sleep

Dr. Susan Carter, MD avatar
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Dec 29, 2025 · 12 min read

In men, winter “low mood” can be true seasonal affective disorder (a recurrent depressive pattern that starts in late fall, peaks in winter, and eases as daylight returns) or a look‑alike driven by physiology—less morning light can delay your circadian rhythm and prolong melatonin, while testosterone, cortisol, and thyroid shifts can produce the same fatigue ...

The science of supplements: Which vitamins actually fight male fatigue?

The science of supplements: Which vitamins actually fight male fatigue?

Dr. Susan Carter, MD avatar
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Dec 18, 2025 · 11 min read

In men with low or marginal levels, repleting key energy cofactors — B vitamins (especially B12, folate, and B6) plus vitamin D and zinc — can reduce fatigue by supporting mitochondrial ATP production and stabilizing testosterone-related energy pathways. Here’s how to spot the signals, confirm them with the right labs, and target what’s actually limiting ...

High estrogen on trt symptoms: What happens when your balance shifts

High estrogen on trt symptoms: What happens when your balance shifts

Dr. Alexander Grant, MD, PhD avatar
Dr. Alexander Grant, MD, PhD: Urologist & Men's Health Advocate
Dec 13, 2025 · 11 min read

On TRT, a portion of injected testosterone is converted by the aromatase enzyme into estradiol, and about 15–20% of men develop elevated estrogen levels that can cause symptoms like water retention, nipple/breast tenderness, mood changes, and sexual dysfunction. Here’s how to recognize the pattern, why it can mimic low‑T, and what to adjust so your ...

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