A calm look at the evidence
Evidence on brain fog, focus, and cognitive energy.
Brain fog, focus, and cognitive energy are noisy topics. Clearhead Lab reads the primary research slowly, so you can settle on what actually holds up — every claim sourced, and a clear conscience about how we're funded.
Shopping for a nootropic right now? We ranked the big branded stacks by whether the finished product was ever put in a human trial — only two of five ever were.
Our clearest pick · $93/mo flat
CoreAge Rx
Doctor-reviewed NAD+ nasal spray (“Hello Energy”) with flat pricing and built-in human support.
Evidence: No human trial for this route. 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.
Things worth reading
What the evidence gently suggests
Unhurried, fully-sourced reviews — written to leave you calmer and clearer, not more anxious about the next thing to buy.
- Evidence note
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.
Read calmly - Evidence note
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.
Read calmly - Evidence note
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.
Read calmly - Evidence note
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.
Read calmly - Evidence note
Best Supplements for Brain Fog, Rated by Evidence
Most brain-fog supplements have weak or no human cognitive data. Here's an honest, evidence-tiered rating — and the few that actually earn a tier.
Read calmly - Evidence note
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.
Read calmly - Evidence note
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.
Read calmly - Evidence note
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.
Read calmly
Evidence, unhurried
Every conclusion traces back to primary research or official labeling — read at a calm pace.
Every claim sourced
Gentle inline citations to the studies, including the null results and the caveats.
Honest about funding
We say so plainly where the evidence behind a product is thin, including for products we earn on.
Read how we work in our editorial policy, and how we stay independent on our about page.