Deep Dives
The research, ranked
Each deep dive ranks what the studies say matters for one topic, with sources and one concrete step per factor.
47 deep divesEvidence
- Mental health and yearsEvidence: Moderate−10 yrs of life, at the median, for people with mental disorders versus the general population, and about two-thirds of their deaths are from physical illness, not suicide.
- What quitting gives backEvidence: Moderate−10 yrs of life for people who keep smoking versus people who never started, in the largest US and UK cohorts.
- What extra weight costsEvidence: Moderate+6.1 yrs of life expectancy associated with bariatric surgery for severe obesity versus usual care, rising to 9.3 years for people with type 2 diabetes (, 174,772 people) — the years attached to weight are recoverable.
- Does sauna add years?Evidence: Low−40% all-cause death risk over 20 years for Finnish men taking a sauna 4 to 7 times a week, compared with once a week. Observational, one cohort, and still the best data there is.
- Exercise that adds yearsEvidence: Moderate+3 yrs of life from just 15 minutes of daily activity versus none, the steepest part of the whole dose-response curve (416,000 adults).
- Eating for more yearsEvidence: Moderate11M deaths a year worldwide are linked to diet, about 1 in 5 of all deaths, led not by sugar or fat but by sodium and missing whole grains (Global Burden of Disease).
- Connection and purposeEvidence: Low+50% higher odds of survival for people with strong social relationships, on par with quitting smoking (148 studies, 308,849 people).
- What alcohol costs youEvidence: Moderate7 drinks a week, about 100 g of alcohol, is roughly where measurable lifespan loss begins across 600,000 drinkers in 83 studies.
- What matters for sleepEvidence: Low+4.7 yrs projected for young men with all five healthy sleep traits, and +2.4 for women.
- Lowering cholesterolEvidence: Moderate−22% fewer heart attacks and strokes for every 1 mmol/L (39 mg/dL) of LDL you lower and keep lowered, in 170,000 trial participants.
- Fixing your metabolismEvidence: Moderate−58% less progression from prediabetes to diabetes with about 5 to 7% weight loss plus 150 weekly minutes of walking, nearly double what metformin managed (Diabetes Prevention Program).
- What runs in familiesEvidence: Moderate<10% of how long you live is explained by your genes, per 400 million family-tree records. Spouses’ lifespans correlate almost as much as siblings’, so most “family resemblance” is habits, not DNA.
- Lowering blood pressureEvidence: Moderate×2 death risk from stroke or heart disease with every 20-point rise in systolic pressure above 115, with no safe plateau (1 million adults).
- How to stay calmEvidence: Low−18% lower all-cause mortality associated with positive psychological well-being in healthy populations (Chida and Steptoe meta-analysis).
- Hearing, vision, brainEvidence: Moderate−48% less cognitive decline over three years in at-risk older adults who got hearing aids, in the ACHIEVE randomized trial. The biggest single modifiable dementia factor is also one of the most treatable.
- Why doctors love fiberEvidence: Moderate−31% lower risk of coronary heart disease death in people eating 25–29 grams of fiber daily versus the lowest intakes — the largest reduction of any outcome in the Reynolds et al. meta-analysis. Each condition has its own estimate, below.
- What your heart needsEvidence: Moderate+9 yrs of life for people with high cardiovascular health versus low, and over half the gain comes from fewer deaths beyond heart disease.
- Protecting your colonEvidence: Moderate−53% fewer colorectal-cancer deaths over 23 years in people who had precancerous polyps found and removed at a colonoscopy.
- Are hot tubs healthy?Evidence: Very low−28% incident cardiovascular disease over 19 years for Japanese adults who bathed in hot water almost every day, versus twice a week or less. This is disease events, not deaths. YapSpan's life model prints a separate, much smaller, explicitly starred estimate built from it (+0.8 years* for almost-daily bathing) — see "The bridge, precisely" below for the math.
- Surviving the roadEvidence: Low24× the death rate per mile for motorcyclists versus car occupants (NHTSA). What you ride, and how, is a genuine longevity input.
- What your skin tells youEvidence: Low>1.5M skin cancers caused by UV radiation each year, with over 120,000 associated deaths globally. Melanoma alone kills ~58,000 people, but caught early, 5-year survival exceeds 99% (NCI SEER).
- Depression and lifespanEvidence: Moderate−7 to −11 yrs of life expectancy with untreated recurrent depression. With active treatment the picture changes: managed depression carried a 24% lower death risk over 8 years, landing near people without depression.
- What an ACE score meansEvidence: Low1 in 6 US adults report four or more adverse childhood experiences; about 61% report at least one (CDC, 25-state survey of 144,017 adults). A high score is common company, not a rare diagnosis.
- Do pets add years?Evidence: Low4 of 8 kinds of pet with any measured link to lifespan: dogs, cats, fish and birds. Horses, rabbits and guinea pigs, reptiles and other animals have never been followed to see how long their owners live, so they get no number, not zero.
- Sports that add yearsEvidence: Low+9.7 yrs of life associated with tennis versus a sedentary life in the 25-year Copenhagen City Heart Study. The social sports top the table.
- Does green space help?Evidence: Very low−4% lower all-cause mortality for each 0.1-unit rise in satellite-measured greenness within 500m of home, pooled across 9 cohort studies and over 8.3 million people in 7 countries. This is the most conservative, best-pooled number on this page — the individual studies below run bigger, and less certain.
- Which diet label wins?Evidence: Moderate−25% heart-disease death risk among vegetarians versus omnivores across nearly 100 studies. Yet all-cause mortality was no different, and in UK cohorts health-conscious meat eaters lived just as long as vegetarians.
- Diet soda, soda or waterEvidence: Low−1.06 kg average body weight change when diet drinks replaced sugary drinks across 12 randomised trials; diet drinks against water showed no clear weight difference in the same analysis of 17 trials and 1,733 adults.
- Plants and your brainEvidence: Low−23% less dementia over nine years in the third of 60,298 UK Biobank adults eating closest to a Mediterranean pattern, versus the third furthest from it. The one diet number on the dementia What Matters chart.
- Coffee, tea and moreEvidence: Low3–5 cups of coffee a day is where mortality risk bottoms out across 402,260 US adults followed for 14 years. Zero is fine too. More is not better.
- Top 10 insomnia fixesEvidence: LowTen insomnia fixes ranked by how strong the research is, each with steps you can try tonight. CBT-I and its two core moves lead, then exercise and an evening walk, relaxation, mindfulness, yoga and tai chi, music, caffeine and alcohol cut-offs and a warm bath. Then 13 more techniques, from worry lists, cognitive shuffling and 4-7-8 breathing to melatonin, eye movements and legs up the wall, each with an honest verdict, plus when to see a doctor.
- Sleep power laws, testedEvidence: Low20–48% lower all-cause mortality in UK Biobank adults with more regular sleep timing than the least regular fifth, among 60,977 people whose sleep was measured by wrist sensors. Observational, so it is a link, not proof.
- Sleep and lifespanEvidence: Low7.9% of all deaths in a cohort of 172,321 US adults were attributable to suboptimal sleep patterns. Adults with all five healthy sleep traits were projected to live 4.7 years longer for men and 2.4 for women.
- How to sleep betterEvidence: Low−45 min of total sleep per night when caffeine is taken too close to bed, across 24 controlled studies, largely without the sleeper noticing.
- Taming inflammationEvidence: Low−15% fewer major cardiovascular events from lowering inflammation alone — cholesterol and blood pressure untouched — in the 10,061-patient CANTOS trial. Inflammation is a cause of the diseases of aging, not a bystander.
- Your Alzheimer’s riskEvidence: Low15–20 yrs before the first symptom is when Alzheimer’s pathology starts accumulating, which makes your 40s and 50s the decade that counts.
- Lower your cognitive ageEvidence: Very low13.7 yrs younger: how frequent video gamers (5+ hours a week of one kind of game) scored on memory, reasoning and verbal tests compared with non-gamers of the same age (Brain and Body study).
- What eyebags tell youEvidence: Very low61% of the variation in eyelid sagging is explained by genetics in twin and cohort data. Most eyebags are inherited anatomy, not disease. The exceptions below are the ones worth knowing.
- Type 2 diabetes riskEvidence: Moderate1 in 3 US adults has prediabetes, and more than 8 in 10 of them do not know it (CDC). Diabetes at 50 costs about 6 years of life.
- Does eating early help?Evidence: Low+28% higher risk of dying from cerebrovascular disease (stroke) for adults whose last meal was after 9pm, compared with before 8pm, across 103,389 adults in the NutriNet-Santé cohort. The single cleanest, most direct signal on this page for "eat dinner earlier" — most of the other numbers below are messier.
- How much water mattersEvidence: Low+39% higher chronic disease risk in adults who run chronically underhydrated, in a 25-year NIH study of 11,000 people. Most other hydration claims are overblown.
- What balding tells youEvidence: Moderate1 in 2 men have pattern hair loss by age 50. It is cosmetic, not lethal, but early crown balding is a surprisingly useful health signal.
- Teeth, gums and lifespanEvidence: Low+24% higher risk of incident coronary heart disease for people with periodontal disease, pooled across 7 good-or-fair-quality cohort studies (range 1.24 to 1.34 depending on how periodontal disease was defined). One of the most consistent single findings in this page’s evidence.
- How to escape dementiaEvidence: Moderate45% of dementia cases worldwide are attributable to 14 risk factors you can act on, most of them decades before symptoms.
- H. pylori and cancerEvidence: Moderate760,000 new cancer cases worldwide in 2024 attributed to H. pylori, the largest number for any infection and about 4% of all cancers, mostly non-cardia stomach cancer.
- Are naps good for you?Evidence: Moderate+22% higher all-cause mortality for naps of 60 minutes or more, versus people who don't nap — pooled across 21 cohort studies and 374,306 adults. Naps under an hour: no measurable increase (hazard ratio 1.00).
- Your Body CheckEvidence: Low5.44× the risk of death from any cause for adults aged 51 to 80 who scored 0 to 3 on the sitting-rising test, compared with those who scored 8 to 10, over a median 6.3 years.
- The years we already citeEssay: the year figures YapSpan cites, next to the checks that exist.
Longevity posts, plain English
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