How easily your brain can lock onto a task and hold it there comes down to a small set of neurotransmitter systems — mainly dopamine and noradrenaline — not effort or discipline. Sleep debt, blood-sugar swings and chronic stress all interfere with that system before a "focus problem" shows up as a symptom, which is why serious research on attention looks at sleep, nutrition and stress load alongside it, not instead of it.

DHA, one of the two omega-3s in Proco's Omega-3, is a structural component of neuronal membranes, with a dose-response relationship to cognitive performance that's been studied across the lifespan. Cognitive Support takes a different angle: caffeine paired with L-theanine, a combination with genuinely consistent trial evidence for alertness without the jitter-and-crash of caffeine alone.

The rest of Cognitive Support's blend has a wider spread of evidence quality, and we'd rather say that plainly than round it up. Bacopa monnieri has genuine trial support for memory — but only after 8–12 weeks of consistent use, not days, which matters if you're judging it against a fast-acting stimulant. Huperzine A and alpha-GPC both act on acetylcholine, the neurotransmitter system most tied to learning and memory; L-tyrosine has trial evidence specifically for cognitive performance under stress or sleep loss, which is a narrower claim than "focus" generally.

Sleep moves through NREM stages, where the body repairs tissue and consolidates memory, and REM, where the brain processes emotional experience. Two systems drive when that happens: homeostatic "sleep pressure" that builds the longer you're awake, and a circadian clock that times when you're actually able to fall asleep. The two can fall out of sync — jet lag, shift work, and late-night screens all do it — which is why "just go to bed earlier" doesn't always work.

Ingredients that support sleep act on different parts of that system: melatonin signals the circadian clock rather than sedating you directly, magnesium and GABA-supporting compounds help the nervous system wind down, and botanicals like valerian and passion flower have their own, smaller evidence base for sleep onset and quality.

Some of that evidence comes with honest caveats worth stating rather than glossing over. GABA taken orally has a real, debated question about whether it crosses the blood-brain barrier in meaningful amounts — we include it because trial data still shows a subjective sleep-quality benefit, not because the mechanism is fully settled. Valerian, lemon balm, chamomile and L-tryptophan each have their own, smaller trial base for sleep onset — real, but more modest than melatonin or magnesium. And St. John's Wort and 5-HTP, both in Sleep Support, have genuine efficacy evidence alongside genuine interaction risk — which is exactly why we flag them rather than only list them.

The HPA axis releases cortisol when you're under load, and the vagus nerve — the main channel of the parasympathetic "rest and digest" system — is what brings the body back down afterward. Chronically elevated cortisol is linked to poorer sleep, memory and mood, but the popular idea of "high cortisol" as a single diagnosable problem is more complicated than the headlines suggest: single-timepoint blood or saliva tests rarely tell the full story, and cortisol naturally swings through the day on its own rhythm.

Magnesium is one of the better-evidenced nutrients for this system, involved in regulating the same HPA-axis and nervous-system signalling that the stress response runs on — which is also why it shows up in both Proco's standalone Magnesium Glycinate and in Sleep Support's blend.

Form matters more than the label usually lets on. "Magnesium" covers several different compounds with different absorption and different evidence bases — glycinate is bound to an amino acid that appears to help it cross into tissue more readily than cheaper forms like oxide, which is why it's the form Proco uses. And where ashwagandha shows up — in Sleep Support's blend — the evidence is specific to standardised extracts like KSM-66 or Sensoril, not the raw herb; extract-vs-herb is the detail most stress-supplement marketing skips.

Mood is regulated by multiple, overlapping systems — serotonin and dopamine signalling, the same HPA axis involved in the stress response, plus sleep, exercise, light exposure and diet — which is why no single ingredient moves it in isolation. A small number of nutrients, omega-3s and magnesium among them, have real clinical trial evidence for a supporting role in mood, particularly where intake is low to begin with.

That's a genuinely different claim from treating clinical depression or anxiety. Those are diagnosable conditions that need proper clinical care — a supplement can be one part of a broader picture, never a substitute for it.

Mood also shifts around specific life transitions — perimenopause, postpartum, grief — each with its own mechanism rather than a single "hormones" or "stress" explanation. See the brain fog section below for what the research says about each.

"Brain fog" isn't a medical term — it's a description of what a dip in attention, processing speed and working memory feels like from the inside. That's exactly why it shows up across such different situations: a bad night's sleep, a hormonal shift, an immune response to a virus, or the flattened concentration that comes with grief. Different mechanism each time, same felt experience. Our full explainer on what actually causes brain fog is the anchor read for this section.

Some of the causes below are ones the four pillars above already cover — poor sleep, stress load, blood-sugar swings. Others are specific life stages or conditions that deserve their own explanation rather than a generic "get more sleep." Where a cause needs a doctor rather than a supplement, we say so.