Meditation and yoga lower measured cortisol a little, on average, in pooled trials, most clearly in people under strain. Other stress markers moved too, mostly in different trials, and the few trials that tested whether cortisol is why yoga helps do not agree.
Moon face is a real sign: most often of prescribed steroid medicine, otherwise of a disease newly diagnosed in a few people per million a year. And hair cortisol’s link to waist size, measured in 24 cohorts, is a correlation of 0.11: about one percent of the difference between one waist and the next.
A physiologist searched for the study behind eight glasses a day and found none. The two candidate origins are a 1945 figure for all the water you take in, which ended by saying thirst is usually an adequate guide, and a 1974 book that said 6 to 8, coffee included.
Across 139,691 people in 17 countries, each 5 kg of weaker grip went with a 16% higher risk of dying, a better predictor than systolic blood pressure. Whether getting stronger lowers that risk is unproven: trials that counted deaths found no clear difference.
A 2025 scoping review found ten places called Blue Zones. Three are well characterised and two of those are fading; Rugao gets more people to 90 but fewer to 100, and Loma Linda was never studied as one.
Finnish men who took 4–7 saunas a week had a 63% lower adjusted risk of sudden cardiac death, a figure resting on 201 men and 10 deaths. Then 20 randomised trials of heat, most of them not Finnish sauna, found almost nothing.
Americans search Google for sleep hygiene well over 100,000 times a month (from a paid keyword database, pulled 6 August 2026). The insomnia guideline advises clinicians against using it as a standalone treatment — and when 241 trials were pulled apart to weigh each ingredient, it scored 1.01. Nothing.
A month-long trial put box breathing against two other breathing techniques and meditation. All three breathing groups got the same small lift after each session, and smaller studies find the square tying with the alternatives more often than beating them.
Around 117,000 Japanese adults were followed for years, and those who said their life felt worth living were less likely to die. None of those studies used the four-circle diagram, which was first published in 2012 with a different word in the middle: purpose.
A 2025 meta-analysis linked 7,000 steps a day to 47% lower mortality (14 studies) and 38% less dementia (2 studies). For death the curve bends near 5,400 steps; cancer risk did not move. Whether age changes the number is still open.