What the evidence actually says

One question per page, read against the research, with a plain verdict on how much weight it holds.

44 questions · 6 capabilities · 80 sources read and checked · 11 verdicts the evidence firmly supports

Does deliberate practice explain expertise?A meta-analysis across five domains found deliberate practice explained 26 per cent of the variance in games, 21 per cent in music, 18 per cent in sports, 4 per cent in education and under 1 per cent in professions. Practice matters most where the rules are fixed and the feedback is immediate, and least where the work is unstructured. The ten thousand hours rule is a popularisation rather than a research finding.

Strength of evidence

  1. traditional
  2. emerging
  3. informed
  4. established
1 source checked · reviewed 17 August 2026
Does alcohol wreck your sleep?

Strength of evidence

evidence-based

Does willpower actually run out?

Strength of evidence

evidence-based

Every brief carries its weight on the page

Nothing here is graded by how much we like it. Each question is read against the studies, then labelled with how much the evidence will actually bear.

evidence-based
Supported by controlled trials or meta-analysis, replicated by more than one research group.
evidence-informed
Real signal in the research, with small studies, small effects, or few controls holding it back.
emerging
Early findings that look promising and need better studies before anyone can be sure.
traditional
Long practised in a living tradition, with limited clinical study behind it.

Three more labels cover ideas whose meaning sits outside experimental trials. This keeps philosophy and metaphor in their proper category.

How we grade the evidence

Browse by capability

Six capabilities of mental longevity. Open one to read every brief in it.

Cognitive clarityFocus, attention, and memoryEmotional regulationStress and calmPsychological flexibilityLearning and adaptingIntentional behaviorHabits and follow-throughSocial connectionRelationships and purposeRestoration capacitySleep, rest, and recovery

Latest briefs

Do grounding techniques work for anxiety?Grounding techniques such as naming what you can see, hear and touch are standard components of therapy for panic and dissociation, and they are described in clinical literature without supporting trials. No randomised evidence tests them as a standalone intervention. The breathing usually bundled with them does have controlled evidence behind it.

Kind of claim

experiential

2 sources checkedDoes multitasking actually cost you?The cost of switching between tasks is well established in laboratory work and grows with how complex the rules are. The separate and more alarming claim, that people who habitually multitask across media have worse cognitive control, produced an effect of 0.17 across 39 assays, and that association became nonsignificant once small-study bias was corrected.

Strength of evidence

evidence-informed

2 sources checkedDo pets improve wellbeing?Across 24 observational studies, pet ownership showed no consistent association with loneliness before COVID-19, with one study finding owners lonelier than non-owners. After the pandemic, about half found reduced loneliness. Social isolation is the outcome with the clearer signal. A therapy dog trial did reduce loneliness in hospitalised older adults, which is a different question from owning one.

Strength of evidence

emerging

2 sources checkedWhy do we procrastinate, and what helps?Psychological treatments reduce procrastination at an effect size of 0.34, rising to 0.55 when the analysis is narrowed to cognitive behavioural therapy. The treatments that work address the emotion the task provokes, and the evidence base is small: 12 studies, 718 participants, with 92 per cent at high risk of bias on blinding.

Strength of evidence

evidence-informed

1 source checkedDoes deliberate practice explain expertise?A meta-analysis across five domains found deliberate practice explained 26 per cent of the variance in games, 21 per cent in music, 18 per cent in sports, 4 per cent in education and under 1 per cent in professions. Practice matters most where the rules are fixed and the feedback is immediate, and least where the work is unstructured. The ten thousand hours rule is a popularisation rather than a research finding.

Strength of evidence

evidence-based

1 source checkedDo sleep trackers help or hurt?Tested against polysomnography, consumer sleep trackers vary enormously, with macro F1 scores from 0.69 for the best down to 0.26 for the worst. Around 36 per cent of people use one regularly, and depending on the threshold applied, between 3 and 14 per cent show orthosomnia, meaning anxiety about sleep driven by the data. Those people had higher insomnia severity at every threshold.

Strength of evidence

evidence-informed

2 sources checked

What we mean by mental longevity

Mental longevity is the lifelong capacity to think clearly, regulate your inner state, adapt to change, keep learning, maintain meaningful connections, and live intentionally.

Put the useful part into practice

HumanOS helps you turn useful evidence into guided work on purpose, patterns, and durable habits.

Join HumanOS free