Reading
Evidence-based research
Every claim on Clearhead Lab is tied to primary research or official labeling. Each row shows how many primary sources the piece cites, and whether it puts an explicit evidence tier on what it covers rather than leaving the verdict in the prose.
Our clearest pick
From $93/mo
CoreAge Rx
NAD+ nasal spray or injection advertised from $93/month, with online clinical review.
Evidence: No rigorous cognition trial. Nasal and injected NAD+ are marketed for cellular energy and focus with no rigorous human cognition or energy trial.
Advertising disclosure · we may earn a commission if you start through this link, at no extra cost to you. See our disclosure.
Why you have brain fog
Long-COVID Brain Fog: Symptoms, Evaluation, and Daily Life
A practical guide to cognitive symptoms after COVID, clinical evaluation, post-exertional malaise, and planning work around your current limits.
5 sourcesUpdated Oct 2026
POTS Brain Fog: Why Posture Matters, and What Studies Show
Brain fog can accompany POTS while standing or seated. Learn what small cognitive studies found and how to describe symptoms for clinical evaluation.
4 sourcesUpdated Oct 2026
ME/CFS Brain Fog: Cognitive Effort, Crashes, and Care Planning
Understand cognitive symptoms in ME/CFS, delayed post-exertional worsening, safe care discussions, and practical ways to prepare for an appointment.
6 sourcesUpdated Oct 2026
Migraine Brain Fog: Before the Headache and After It
Why thinking can feel slower around migraine attacks, what diary studies found, and when new symptoms need care instead of being labeled aura.
4 sourcesUpdated Oct 2026
Brain Fog After Concussion: Warning Signs and Recovery
Trouble thinking after a head injury needs assessment. Learn emergency warning signs, what recovery guidance says, and how to plan work or school.
4 sourcesUpdated Oct 2026
Brain Fog vs. Dementia: What the Difference Can Tell You
Brain fog is a symptom description, not a dementia diagnosis. Learn why daily function, symptom timing, and clinical evaluation matter more than a checklist.
4 sourcesUpdated Oct 2026
What Actually Causes Brain Fog?
Brain fog is a symptom, not a diagnosis. The real, evidence-based drivers — sleep loss, post-viral illness, stress — and why one supplement rarely fixes it.
4 sourcesUpdated Jul 2026
Menopause Brain Fog: Causes & What Actually Helps
Menopause brain fog is real and usually temporary. An honest look at the causes, what the evidence says helps, and what supplements can't fix.
13 sourcesUpdated Aug 2026
Anxiety Brain Fog: Why Worry Clouds Your Thinking
Anxiety taxes the attention and working memory you think with. Why worry causes brain fog — and why treating the anxiety, not a supplement, is the real fix.
10 sourcesEvidence-tieredUpdated Jul 2026
ADHD and Brain Fog: The Overlap and What Actually Helps
ADHD's attention and working-memory deficits feel like brain fog — but aren't the same, and a nootropic isn't ADHD treatment. An honest, evidence-first guide.
8 sourcesEvidence-tieredUpdated Jul 2026
Thyroid Brain Fog: How Hypothyroidism Clouds Your Mind
An underactive thyroid is a classic, testable cause of brain fog. Why hypothyroidism slows thinking, why fog can persist on treatment, and why to test TSH.
8 sourcesEvidence-tieredUpdated Jul 2026
Brain Fog After Eating: The Blood-Sugar and Insulin Connection
Why a meal can leave you foggy and sleepy — the postprandial glucose-and-insulin story, what the evidence shows, and the food-order fixes that beat any pill.
11 sourcesEvidence-tieredUpdated Jul 2026
Why You Wake Up With Brain Fog
Grogginess on waking has ordinary causes: sleep inertia, overnight dehydration, a blood-sugar dip — and sometimes undiagnosed sleep apnea. What helps, honestly.
7 sourcesUpdated Jul 2026
Sleep Apnea and Brain Fog
Obstructive sleep apnea is a common, underdiagnosed driver of brain fog. How it clouds thinking, what CPAP can (and can't) reverse, and why to screen first.
8 sourcesEvidence-tieredUpdated Jul 2026
B12 Deficiency Brain Fog: Signs, Testing, and Reversal
Low B12 can cloud thinking before anemia shows up — and it's often reversible with repletion. Why to test, what the evidence shows, and when to see a doctor.
9 sourcesEvidence-tieredUpdated Jul 2026
Iron Deficiency, Anemia, and Brain Fog
Low iron can dull focus and energy even before anemia — and even with a normal blood count. Why ferritin matters, what fixes it, and how to absorb iron better.
9 sourcesEvidence-tieredUpdated Jul 2026
Can Low Vitamin D Cause Brain Fog?
Low vitamin D is linked to foggier thinking, and fixing a real deficiency makes sense — but vitamin D is not a cognitive enhancer if your levels are fine.
9 sourcesEvidence-tieredUpdated Jul 2026
Dehydration Brain Fog: How Mild Fluid Loss Dulls Focus
Losing just 1–2% of body water can blunt attention, memory, and mood — often before you feel thirsty. Here's the evidence, and the cheapest, fastest fog fix.
10 sourcesEvidence-tieredUpdated Jul 2026
Does Ozempic Cause Brain Fog?
Brain fog isn't a labeled Ozempic side effect. When it happens it's usually from eating too little, dehydration, or low blood sugar — the honest evidence.
10 sourcesEvidence-tieredUpdated Jul 2026
Brain Fog After Quitting Weed: The Recovery Timeline
Foggy thinking after quitting cannabis is real but usually temporary. Withdrawal fog peaks in week one and typically clears in 2–4 weeks — the honest timeline.
8 sourcesEvidence-tieredUpdated Jul 2026
Alcohol Brain Fog: Why Your Mind Is Hazy the Day After
Next-day brain fog after drinking is real and measurable. Here's what the hangover-cognition research shows — and the four mechanisms behind the haze.
14 sourcesEvidence-tieredUpdated Oct 2026
Medications That Cause Brain Fog: The Common Culprits
Anticholinergics, benzodiazepines, opioids, and sedating antihistamines can cloud thinking. The honest evidence on which drugs do it — and why not to just stop.
13 sourcesEvidence-tieredUpdated Jul 2026
Does Benadryl Cause Brain Fog?
Yes — diphenhydramine is sedating and anticholinergic, and impairs attention more than alcohol in trials. The evidence, the dementia signal, and the easy fix.
10 sourcesUpdated Jul 2026
Statins and Brain Fog: What the Evidence Actually Shows
Large trials show statins cause no average cognitive decline; most fog is nocebo and rare cases reverse. The honest evidence — and why not to self-stop.
12 sourcesEvidence-tieredUpdated Jul 2026
Chemo Brain: Why It Happens and What Actually Helps
Chemo brain is real and common during cancer treatment, and often lingers afterward. What the evidence shows about why it happens — and what genuinely helps.
10 sourcesEvidence-tieredUpdated Jul 2026
Postpartum "Mom Brain": Why It Happens and When It Lifts
Postpartum brain fog is real — driven by sleep loss, hormonal shifts, and nutrient depletion. When it lifts, what to check, and what's safe while nursing.
10 sourcesEvidence-tieredUpdated Jul 2026
Blood Sugar and Brain Fog: The Diabetes Connection
In diabetes, both high and low blood sugar cloud thinking. Why dysglycemia causes brain fog — and why the fix is glycemic control, not a focus supplement.
10 sourcesUpdated Jul 2026
Gluten, Celiac & Brain Fog: What the Evidence Shows
Brain fog is real and documented in celiac disease and gluten sensitivity — but test for celiac BEFORE going gluten-free, or you can ruin the diagnosis.
8 sourcesUpdated Jul 2026
Depression and Brain Fog: Why It Happens and What Helps
Cognitive symptoms affect most people with depression and can linger after mood lifts. Why it happens — and why treating the depression comes first.
8 sourcesUpdated Jul 2026
Perimenopause Brain Fog: Why It Hits Before Menopause
Why brain fog often hits hardest in early perimenopause — before periods stop. It's common, mostly transient, and not early dementia. What the evidence shows.
13 sourcesUpdated Aug 2026
Caffeine Crash Brain Fog: The Afternoon Slump Explained
The afternoon crash isn't a caffeine deficiency — it's adenosine rebound as coffee wears off, plus a blood-sugar dip from lunch. The honest fixes explained.
14 sourcesEvidence-tieredUpdated Jul 2026
Fibromyalgia Brain Fog ("Fibro Fog"): Why It Happens and What Helps
Fibro fog causes memory and concentration trouble in fibromyalgia. Evidence, practical coping tools, treatment limits, and signs that need medical assessment.
12 sourcesEvidence-tieredUpdated Oct 2026
Can Birth Control Cause Brain Fog? An Honest Look at the Evidence
Can the pill cause brain fog? The evidence is mixed and effects subtle, not dramatic. What's real, what's likely something else, and what to do about it.
6 sourcesEvidence-tieredUpdated Jul 2026
Semaglutide & Brain Fog: What the Cognition Trials Found
What semaglutide cognition trials found, why brain-fog symptoms are a separate question, and what the evidence does and does not show.
7 sourcesEvidence-tieredUpdated Oct 2026
Nootropics & supplements
L-Theanine for Focus (and the Caffeine Combo): What the Evidence Shows
L-theanine plus caffeine has the strongest consumer evidence of any nootropic — but effects are modest and acute, not transformative. Honest dosing and proof.
13 sourcesEvidence-tieredUpdated Aug 2026
Magnesium for Brain Fog & Focus: Threonate, Glycinate & More
Does magnesium clear brain fog? An honest look: deficiency correction is the real lever, L-threonate's brain claim is thin in humans, and the forms compared.
14 sourcesEvidence-tieredUpdated Jul 2026
Lion's Mane for Brain Fog & Focus: What the Evidence Shows
Lion's mane is sold hard for focus and 'brain regeneration.' The human evidence is a handful of small, short trials — here's what they actually found, honestly.
11 sourcesEvidence-tieredUpdated Jul 2026
Ashwagandha for Stress & Brain Fog: What the Evidence Shows
Ashwagandha has real RCT support for lowering stress and cortisol and improving sleep — but "clears brain fog" is the indirect, weaker claim. An honest review.
14 sourcesEvidence-tieredUpdated Jul 2026
Citicoline (CDP-Choline) for Focus and Brain Fog: The Evidence
Citicoline is the best-evidenced choline nootropic, with small RCTs on attention and processing speed. Honest dosing, the alpha-GPC comparison, and the limits.
8 sourcesEvidence-tieredUpdated Jul 2026
Creatine for Brain Fog and Mental Energy: What the Evidence Shows
Creatine's cognitive benefit is real but conditional — concentrated under sleep deprivation and metabolic stress, and mixed in well-rested healthy adults.
10 sourcesEvidence-tieredUpdated Jul 2026
Rhodiola Rosea for Brain Fog & Mental Fatigue: The Evidence
Rhodiola's best evidence is for stress-related mental fatigue and burnout — but the data are contradictory and the trials flawed. An honest review and dosing.
12 sourcesEvidence-tieredUpdated Jul 2026
Bacopa Monnieri for Memory & Brain Fog: The Evidence
Bacopa may help recall in some trials, but later reviews find inconsistent cognitive benefits. Studied extracts, timelines, safety, and what to expect.
12 sourcesEvidence-tieredUpdated Oct 2026
Alpha-GPC for Focus & Mental Clarity: The Evidence
Alpha-GPC is a cholinergic precursor, but its focus evidence in healthy adults is thin — and an observational study flagged a stroke-risk signal. Honest review.
8 sourcesUpdated Aug 2026
Omega-3 (DHA) for Brain Fog: Does It Actually Help?
Omega-3s like DHA do real work in the brain, but the cognitive benefit is clearest when intake is low — and underwhelming if your levels are already fine.
10 sourcesEvidence-tieredUpdated Jul 2026
Caffeine and L-Theanine: The Dosing, Ratio, and Evidence for the "Calm Focus" Stack
Caffeine plus L-theanine is the best-evidenced nootropic stack. The dosing (1:2 ratio explained), what randomized trials really show, and who it suits.
12 sourcesEvidence-tieredUpdated Jul 2026
Noopept: What the Evidence Shows for Focus and Memory
Noopept is a popular synthetic nootropic, but its evidence rests on small, older Russian trials — with no large Western RCTs in healthy people. Honest review.
1 sourceEvidence-tieredUpdated Jul 2026
Ginkgo Biloba for Memory and Focus: What the Evidence Really Shows
Ginkgo biloba (EGb 761) is heavily studied — and mostly disappointing for healthy memory. The honest, evidence-first read on what to actually expect.
2 sourcesEvidence-tieredUpdated Aug 2026
Exercise for Brain Fog and Mental Clarity: What the Evidence Shows
Exercise is the most under-sold cognitive tool there is — real, replicated human evidence for attention and memory, with honest limits on how big the effect is.
6 sourcesEvidence-tieredUpdated Jul 2026
L-Tyrosine for Focus and Mental Energy: What the Evidence Actually Shows
L-tyrosine is not a general focus booster. Its real evidence is narrow: cognition under acute stress, sleep loss, and heavy multitasking — not everyday use.
6 sourcesEvidence-tieredUpdated Jul 2026
NAD+ & precursors
NAD+ Injection Side Effects: Safety Questions Before Treatment
FDA reports, sterile-compounding risks, and limits of NAD+ injection evidence. What to ask a prescriber and how to respond to concerning symptoms.
5 sourcesUpdated Oct 2026
NAD+, Brain Fog & Focus: What the Evidence Shows
NAD+ precursors raise blood NAD+, but do they actually lift brain fog or sharpen focus? An honest, fully-sourced look at what human trials really found.
16 sourcesEvidence-tieredUpdated Jul 2026
Does NAD+ Help Brain Fog? An Evidence Check
Does NAD+ actually lift brain fog? Honestly, little-to-no human evidence. What the trials found, why nasal/IV claims are unproven, and what to rule in first.
12 sourcesUpdated Jul 2026
NAD+ Nasal Spray: Does It Work for Focus?
NAD+ nasal spray is sold for focus and energy. No human trial has tested the route, it isn't FDA-approved, and here's what every NAD+ format costs.
13 sourcesEvidence-tieredUpdated Aug 2026
NAD+ for Long-COVID Brain Fog: What's the Evidence?
The first randomized trial raised NAD+ but didn't improve cognition or fatigue. The honest evidence on NAD+ for long-COVID brain fog — and what to do instead.
10 sourcesUpdated Jul 2026
NAD+ vs Nootropics for Focus: An Honest Comparison
Neither NAD+ nor most nootropics have strong human focus evidence. An honest, evidence-tiered comparison — and the few things that modestly work.
13 sourcesEvidence-tieredUpdated Jul 2026
NAD+ for Cognitive Energy & Fatigue: What the Evidence Shows
NAD+ precursors reliably raise the biomarker but haven't beaten placebo for fatigue or mental energy in the best trials. An honest, evidence-first review.
12 sourcesEvidence-tieredUpdated Jul 2026
NMN & NR for Brain Health: What the Studies Actually Show
NMN and NR reliably raise NAD+ and look safe — but in the best human trials they haven't improved cognition. An honest, citation-first evidence review.
14 sourcesEvidence-tieredUpdated Jul 2026
NAD+ IV for Mental Clarity: Is It Worth It?
NAD+ IV drips are marketed for mental clarity, but no rigorous trial tests them for cognition. An honest, evidence-first look at what the science shows.
12 sourcesUpdated Aug 2026
Liposomal NAD+ for the Brain: The Absorption Reality
Liposomal NAD+ is sold as a better-absorbed brain booster. Here's the honest absorption science — and why no human trial shows it helps cognition.
12 sourcesUpdated Aug 2026
NAD+ Dosing for Cognitive Benefits: What the Evidence Actually Supports
There's no established NAD+ dose proven to sharpen cognition. What dose-ranging trials actually show, and the honest limits behind every number.
14 sourcesUpdated Aug 2026
NAD+, Stress & Mood: What's the Real Link?
NAD+ is tied to stress and mood through plausible lab pathways, but no trial proves a supplement lifts mood. An honest, evidence-first review.
12 sourcesUpdated Jul 2026
Buyer's guides
Best Supplements for Brain Fog, Rated by Evidence
Brain fog has a cause. Match yours — B12, iron, vitamin D, magnesium, omega-3, sleep — to the fix with real evidence, then see how the popular pills rate.
14 sourcesEvidence-tieredUpdated Aug 2026
How to Clear Brain Fog (What Actually Helps)
There's no instant cure for brain fog. The evidence-based playbook: rule in real causes first, then the lifestyle levers and supplements that genuinely help.
14 sourcesUpdated Jul 2026
Best Supplements for Focus & Concentration, Rated by Evidence
Most focus supplements are sold far ahead of their proof. Here's an honest, evidence-tiered rating of what actually helps attention — and what doesn't.
15 sourcesEvidence-tieredUpdated Aug 2026
Best Supplements for ADHD Focus (Non-Stimulant, Evidence-Ranked)
Supplements complement, never replace, evidence-based ADHD care. Only EPA-heavy omega-3 has real symptom-level trial data — and it's modest. Evidence-ranked.
10 sourcesEvidence-tieredUpdated Jul 2026
Best Nootropics for Focus: An Honest, Evidence-First Guide
Most focus nootropics are sold ahead of their proof. An evidence-ranked guide to what actually helps attention — single ingredients and popular blends.
7 sourcesEvidence-tieredUpdated Jul 2026
Product reviews
CoreAge Rx NAD+ Review: $93 Starting Price, Refund Fine Print
CoreAge Rx offers nasal and injectable NAD+ from $93/month. We check the price wording, refund exclusions, care model, and brain-fog evidence.
8 sourcesUpdated Oct 2026
HealthRX NAD+ Review: $161 Injection Plan and What Is Included
HealthRX publishes NAD+ prices, injection quantity, and prepay terms. Our review checks the $161 plan, nasal option, refunds, and evidence limits.
7 sourcesUpdated Oct 2026
RxSpan MD NAD+ Review: Routes, Prices, and Visit Fees
RxSpan MD lists NAD+ injection, nasal spray, and flex-dose tablets. We compare $249/$199 base prices, prepay totals, and the consultation-fee caveat.
6 sourcesUpdated Oct 2026
Willow NAD+ Review: $199 Plan, Supply, and Support
Willow advertises NAD+ injections at $199/month. We review the schedule, support, pharmacy disclosures, subscription caveats, and cognitive evidence.
5 sourcesUpdated Oct 2026
Enhance MD NAD+ Review: Read the Four-Week Billing First
Enhance MD offers NAD+ injections and wafers. We compare four-week billing, longer plans, support, pharmacy disclosures and the limits of the evidence.
6 sourcesUpdated Oct 2026
AgelessRx NAD+ Review: Intro Pricing, Three Formats and Evidence
AgelessRx NAD+ reviewed: the $79 injection introduction, $149 follow-on rate, nasal and patch options, cancellation and what its research actually shows.
7 sourcesUpdated Oct 2026
Hone Health NAD+ Review: $199 Standalone or Membership Pricing
Hone offers NAD+ without a membership for $199/month. We compare the $165 member rate, Basic fees, physician review and questions to settle before buying.
9 sourcesUpdated Oct 2026
Mind Lab Pro Review: Does It Actually Work?
Mind Lab Pro has two Leeds RCTs and discloses every dose — better-evidenced than most stacks. But is the premium 11-ingredient blend worth it? An honest review.
8 sourcesEvidence-tieredUpdated Oct 2026
Qualia Mind Review: 28 Ingredients, How Much Evidence?
Qualia Mind packs 28 ingredients into one stack — but its own company trial was never published, and much of the 'focus' is likely just ~90 mg of caffeine.
6 sourcesEvidence-tieredUpdated Oct 2026
Alpha Brain Review: Is Onnit's Nootropic Worth It?
Onnit's Alpha Brain has two company-funded trials with a mixed memory signal — but it hides doses in proprietary blends and is overpriced. An honest review.
6 sourcesEvidence-tieredUpdated Oct 2026
Magic Mind Review: Productivity Shot or Pricey Matcha?
Magic Mind is a 2oz matcha shot (~55mg caffeine) plus lion's mane and adaptogens. We compare the ingredient evidence, caffeine, price and subscription terms.
10 sourcesEvidence-tieredUpdated Oct 2026
Thesis Nootropics Review: Do "Personalized" Blends Work?
Thesis maps a quiz to one of a few fixed blends and calls it "personalized." No finished-product trials exist — just testimonials. An honest review.
11 sourcesEvidence-tieredUpdated Oct 2026
MyDrHank NAD+ Review: Starting Price, Care and Plan Questions
MyDrHank advertises NAD+ from $137/month, depending on protocol and dose. Compare included care, renewal questions, pharmacy disclosures and evidence limits.
2 sourcesUpdated Oct 2026
Shed NAD+ Review: The $144 You Cannot Buy for One Month
Shed prices NAD+ at $144–$169 a month with no prepay ladder — then its terms set a two-month minimum on every program. We read both documents.
4 sourcesEvidence-tieredUpdated Oct 2026
Lttl NAD+ Review: Monthly Pricing, Prepaid Plans and Evidence
Lttl NAD+ costs $149 on the monthly plan. Compare its $99 introduction, prepaid commitments, pharmacy disclosures and the limits of the brain-fog evidence.
5 sourcesUpdated Oct 2026
Pallas Health NAD+ Review: Four-Week Pricing and Care
Pallas NAD+ injection lists $139 initially, then $179 every four weeks. Understand the renewal cadence, annual-plan headline, included care and evidence limits.
5 sourcesUpdated Oct 2026
Strut Health NAD+ Review: The Page Describes the Wrong Molecule
Strut sells a 500 mg NAD+ injection from $149 and prints the dose — then explains NAD+ as a peptide that signals the pituitary. It isn't one.
5 sourcesUpdated Oct 2026
Breeze Meds NAD+ Review: Three Prices, and No Terms of Service
Breeze Meds names four pharmacies and two NPI-verified doctors, then prices one NAD+ injection three ways — on a site with no refund policy at all.
5 sourcesUpdated Oct 2026
Synergy Rx NAD+ Review: Pricing, Terms and Evidence
Synergy Rx advertises NAD+ starting at $275. We review supply and renewal questions, refund terms, public disclosures and the clinical evidence.
4 sourcesUpdated Oct 2026
Ageless NAD+ Review: Troches, Injection and Cost
Ageless lists a $149 NAD+ troche and $199 injections. Compare dose-dependent prices, pharmacy questions and the FDA warning letter to its associated operator.
4 sourcesUpdated Oct 2026
He & She MD NAD+ Review: Monthly and Annual Plan Pricing
He & She MD lists NAD+ at $229 monthly or a $139 annual-plan equivalent. Compare commitments, conflicting price copy and questions to ask before enrollment.
1 sourceUpdated Oct 2026
Oak NAD+ Review: Published Pricing, Included Care and Questions
Oak now advertises NAD+ injections from $175/month. Review included care, the regular $199 price, pharmacy questions and the limits of the evidence.
2 sourcesUpdated Oct 2026
Head-to-head
Noopept vs Piracetam: How the Two 'Racetam-Family' Nootropics Compare
Noopept and piracetam are often pitted against each other. Honest comparison: noopept is far more potent, but both rest on thin, older evidence.
1 sourceUpdated Jul 2026
Ginkgo vs Bacopa for Memory: Which Herbal Nootropic Has Better Evidence?
Ginkgo has a big but unreliable evidence base; Bacopa's is smaller but more consistently positive for recall. The honest, evidence-first head-to-head.
5 sourcesUpdated Jul 2026
Alpha-GPC vs Citicoline: Which Choline Nootropic Is Better for Focus?
Both raise brain choline, but the evidence and safety profiles differ. For a focus or brain-fog goal, citicoline is the better-evidenced, cleaner-profile pick.
12 sourcesEvidence-tieredUpdated Jul 2026
Everything else
What Is Food Noise? Meaning, Measurement & How to Quiet It
Food noise is persistent, unwanted thinking about food. The formal definition, the questionnaire behind it, the critique, and what GLP-1s do and don't prove.
7 sourcesUpdated Jul 2026
Does a GLP-1 Make You Tired? What the FDA Labels Say
Semaglutide and tirzepatide fatigue rates read straight from the FDA labels: which products tabulate it, which don't, and what the placebo columns show.
9 sourcesEvidence-tieredUpdated Jul 2026
Zepbound for Sleep Apnea: What the Evidence Shows
Zepbound is FDA-approved for moderate-to-severe sleep apnea in adults with obesity. The AHI results — and why the label prints no sleepiness score at all.
6 sourcesUpdated Jul 2026