What the evidence actually says

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

37 questions · 6 capabilities · 68 sources read and checked · 10 verdicts the evidence firmly supports

Does alcohol wreck your sleep?Alcohol reliably shortens the time it takes to fall asleep and damages the second half of the night. It suppresses REM sleep in a dose-dependent way early on, then produces more waking and light sleep as it clears. Tolerance to the sedative effect develops within about three nights, so the help fades while the disruption remains.

Strength of evidence

  1. traditional
  2. emerging
  3. informed
  4. established
1 source checked · reviewed 17 August 2026
Does willpower actually run out?

Strength of evidence

evidence-based

How do you actually lower cortisol?

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

Does music help you study?The overall effect of background music across every outcome averages out to nothing, because the specific effects run in opposite directions and cancel. Music reliably disturbs reading and has small negative effects on memory, while improving mood and sports performance. Lyrics in a language you understand cause the damage, and habitual listeners suffer far less than people unused to it.

Strength of evidence

evidence-informed

2 sources checkedDoes social media make you lonely?Across 26 longitudinal studies and nearly 25,000 people, loneliness predicts later problematic media use at about the same weak strength that use predicts later loneliness, both around 0.10. Trials that ask people to limit their use show a small improvement in depression. Trials that ask people to quit completely show nothing, on any wellbeing measure tested.

Strength of evidence

evidence-informed

3 sources checkedDo morning routines actually matter?Morning types show better outcomes on several measures, and the mechanism appears to be sleep rather than timing. In one analysis chronotype had no direct effect on academic achievement at all, and worked entirely through sleep quality and daytime sleepiness. No trial supports the specific five o'clock routines sold online, and the evidence that exists is largely cross-sectional.

Strength of evidence

emerging

1 source checkedDoes a growth mindset actually work?Believing ability can grow is associated with achievement weakly, accounting for roughly one per cent of the variance across hundreds of thousands of students. Interventions produce small effects overall, and later analyses correcting for publication bias and study quality reduce them further. Where benefit appears it is concentrated in students who are academically at risk or from low socioeconomic backgrounds.

Strength of evidence

evidence-informed

2 sources checkedDoes alcohol wreck your sleep?Alcohol reliably shortens the time it takes to fall asleep and damages the second half of the night. It suppresses REM sleep in a dose-dependent way early on, then produces more waking and light sleep as it clears. Tolerance to the sedative effect develops within about three nights, so the help fades while the disruption remains.

Strength of evidence

evidence-based

1 source checkedIs your attention span really shrinking?The famous claim that human attention has fallen to eight seconds, below a goldfish, has no traceable source and the goldfish comparison appears invented. Something measurable has changed: research tracking people at work found average time on a screen before switching fell from about two and a half minutes in 2004 to roughly 47 seconds. That is switching behaviour, and it is not the same as a shrinking capacity to attend.

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.

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