Cognitive performance is a system
of connected mental abilities

Someone can have an excellent memory but struggle to sustain attention. Another person may think quickly but find it difficult to organise a complex task. A third may perform well in quiet conditions but deteriorate under sleep loss, stress or competing demands.

That is why broad claims such as “improves brain function” are often unhelpful. The more useful question is which cognitive domain is being measured, under what conditions and in which population.

Focus depends on alertness,
selection and control

Attention begins with sufficient alertness. You then need to direct that alertness towards relevant information and resist competing sights, sounds, thoughts and notifications. Sustained attention is the ability to continue doing this over time.

Modern work often creates the illusion of multitasking. In reality, many tasks require rapid switching. Each switch carries a cognitive cost because the brain must disengage one rule set and activate another. This can create a sense of busyness while reducing accuracy and depth of thought.

Sleep loss affects attention
before every domain fails

People often judge their cognitive state by how awake they feel, but subjective confidence and objective performance do not always move together. Sleep restriction can increase lapses even when someone believes they are functioning adequately.

A 2024 meta-analysis combined 44 studies in which adults were restricted to two to six hours of sleep opportunity for one night. Sleepiness increased substantially, and sustained-attention tasks showed slower reactions and more lapses. Working memory and inhibitory control were not consistently impaired after a single restricted night, demonstrating that different domains respond differently.

Exercise supports cognition
through more than fitness

Physical activity affects blood flow, insulin sensitivity, mood, sleep, vascular health and the molecular environment in which the brain functions. These pathways overlap, so no single mechanism explains every cognitive effect.

A meta-analysis of 54 randomised controlled trials in healthy populations found benefits across overall cognition and the domains studied. Aerobic exercise showed the strongest average benefit for global cognition, resistance exercise for executive function and mind-body exercise for memory. Effects varied by age and programme design.

Read the current UK Chief Medical Officers’ physical activity guidance.

Feeling more alert is not the same
as improving every form of thinking

Caffeine blocks adenosine receptors and can acutely improve alertness and attention. That makes it useful for some tasks, but it does not create sleep, guarantee better judgment or improve every higher-order cognitive outcome.

A 2025 meta-analysis of 31 double-blind, placebo-controlled trials in rested healthy adults found small improvements in both attention accuracy and reaction time. Higher doses continued to improve reaction time, but accuracy followed a curved relationship and stopped improving beyond a point.

The biological rationale is strong,
but cognitive results remain mixed

Creatine helps buffer cellular energy by supporting rapid ATP regeneration. The brain contains creatine and phosphocreatine, which creates a plausible reason to investigate supplementation during demanding cognitive conditions.

A 2024 meta-analysis included 16 randomised trials and 492 participants. It reported benefits for memory, attention time and processing-speed time, but not for overall cognition or executive function. Evidence certainty was moderate for memory and low for several other outcomes.

A separate 2024 systematic review concluded that supplementation can increase brain creatine content but described cognitive findings as equivocal. Taken together, the evidence is promising in selected domains and populations, but it does not justify claiming a universal nootropic effect.

Read: Creatine for Cognitive Performance.

Human trials are interesting,
but still small and preliminary

Lion’s Mane, or Hericium erinaceus, contains compounds being studied in relation to nerve-growth signalling and brain function. Laboratory and animal findings have generated substantial interest, but human cognitive evidence remains limited.

A small 2009 trial enrolled 30 adults aged 50 to 80 with mild cognitive impairment. Cognitive scores improved during 16 weeks of intake but declined after supplementation stopped. The study was small, used a specific preparation and involved people with diagnosed impairment, so it cannot establish an everyday focus benefit in healthy adults.

In a 2025 acute crossover trial involving 18 healthy adults aged 18 to 35, a single dose did not improve global cognition or mood compared with placebo. One individual motor task improved, reinforcing the need to distinguish a task-specific result from a broad cognitive effect.

Read: How to Choose a Lion’s Mane Supplement.

Build reliable performance before
chasing an instant boost

Go deeper into the ingredients
and systems behind performance

• Creatine: Creatine for Cognitive Performance.
• Lion’s Mane: Fruiting Body, Mycelium, Dose and Purity.
• Ingredient comparison: Lion’s Mane vs Ashwagandha.
• Cellular energy: How Your Cells Make Energy.