Sources

Every source this site leans on. Each entry says who wrote it, what kind of evidence it is and what that kind can show, the one point I use from it, and the day I last opened it.

• World Health Organization (2026). Healthy diet (fact sheet).

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: At least 400 g of fruit and vegetables a day; free sugars under 10% of daily energy; salt under 5 g a day for adults.

  Checked Oct 11, 2026 · https://www.who.int/news-room/fact-sheets/detail/healthy-diet

• Klein and Kiat (2015). Detox diets for toxin elimination and weight management: a critical review of the evidence.

  Review: experts read and summed up the research.

  What we use: Very little clinical evidence supports detox diets; the authors found no randomised trials of commercial detox diets in people.

  Checked Oct 11, 2026 · https://doi.org/10.1111/jhn.12286 · DOI 10.1111/jhn.12286 · PubMed 25522674

• US Centers for Disease Control and Prevention (2024). About sleep.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: Adults 18 to 60: 7 or more hours a night. Habits: steady bed and wake times; devices off 30 minutes before bed; no caffeine late in the day.

  Checked Oct 11, 2026 · https://www.cdc.gov/sleep/about/index.html

• American Academy of Sleep Medicine and Sleep Research Society (2015). Recommended amount of sleep for a healthy adult: a joint consensus statement.

  Expert consensus: what a panel of specialists agreed on.

  What we use: Healthy adults should sleep at least 7 hours a night; 6 or fewer is too little to sustain health. No upper limit was set.

  Checked Oct 11, 2026 · https://doi.org/10.5665/sleep.4716 · DOI 10.5665/sleep.4716 · PubMed 26039963

• World Health Organization (Bull and colleagues) (2020). World Health Organization 2020 guidelines on physical activity and sedentary behaviour.

  Guideline: an expert panel weighed the evidence and made a recommendation.

  What we use: Adults: 150 to 300 minutes of moderate or 75 to 150 minutes of vigorous activity a week; muscle-strengthening for all ages; some activity is better than none; sit less.

  Checked Oct 11, 2026 · https://doi.org/10.1136/bjsports-2020-102955 · DOI 10.1136/bjsports-2020-102955 · PubMed 33239350

• World Health Organization (2024). Physical activity (fact sheet).

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: Any amount of physical activity is better than none; all age groups should limit time sitting.

  Checked Oct 11, 2026 · https://www.who.int/news-room/fact-sheets/detail/physical-activity

• Albulescu and colleagues (2022). "Give me a break!" A systematic review and meta-analysis on the efficacy of micro-breaks for increasing well-being and performance.

  Pooled analysis of many studies, 22 study samples, 2,335 people: an average across studies; only as good as the studies inside.

  What we use: Short breaks gave a small lift in energy and a small drop in tiredness; the effect on work output was not clear.

  Checked Oct 11, 2026 · https://doi.org/10.1371/journal.pone.0272460 · DOI 10.1371/journal.pone.0272460 · PubMed 36044424

• White and colleagues (2019). Spending at least 120 minutes a week in nature is associated with good health and wellbeing.

  Survey, 19,806 people in England: shows a link, not a cause.

  What we use: People who spent 120 minutes or more a week in nature were more likely to report good health and wellbeing; it did not matter how the time was split up. A link, not proof of cause.

  Checked Oct 11, 2026 · https://doi.org/10.1038/s41598-019-44097-3 · DOI 10.1038/s41598-019-44097-3 · PubMed 31197192

• Singh and colleagues (2023). Effectiveness of physical activity interventions for improving depression, anxiety and distress: an overview of systematic reviews.

  Review of reviews, 97 reviews, 1,039 trials, 128,119 people: pulls together many reviews; only as good as the reviews inside.

  What we use: Physical activity eased symptoms of depression, anxiety and distress across many groups of adults, compared with usual care.

  Checked Oct 11, 2026 · https://doi.org/10.1136/bjsports-2022-106195 · DOI 10.1136/bjsports-2022-106195 · PubMed 36796860

• Holt-Lunstad and colleagues (2010). Social relationships and mortality risk: a meta-analytic review.

  Pooled analysis of many studies, 148 studies, 308,849 people: an average across studies; only as good as the studies inside.

  What we use: People with stronger social ties were more likely to be alive at follow-up than people with weaker ties.

  Checked Oct 11, 2026 · https://doi.org/10.1371/journal.pmed.1000316 · DOI 10.1371/journal.pmed.1000316 · PubMed 20668659

• Dunlosky and colleagues (2013). Improving students' learning with effective learning techniques.

  Review: experts read and summed up the research.

  What we use: Practice testing and spreading study out over time rated most useful; rereading and highlighting rated low.

  Checked Oct 11, 2026 · https://doi.org/10.1177/1529100612453266 · DOI 10.1177/1529100612453266 · PubMed 26173288

• Cepeda and colleagues (2006). Distributed practice in verbal recall tasks: a review and quantitative synthesis.

  Pooled analysis of many studies, 317 experiments: an average across studies; only as good as the studies inside.

  What we use: Spacing study sessions apart helps people remember longer; the longer you need to remember, the wider the best gap.

  Checked Oct 11, 2026 · https://doi.org/10.1037/0033-2909.132.3.354 · DOI 10.1037/0033-2909.132.3.354 · PubMed 16719566

• World Health Organization (2009). WHO calls for tighter standards on indoor radon.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: Reference level of 100 Bq/m3 for indoor radon; no higher than 300 Bq/m3 where 100 can't be reached.

  Checked Oct 11, 2026 · https://www.who.int/news/item/21-09-2009-who-calls-for-tighter-standards-on-indoor-radon

• US Environmental Protection Agency. What is EPA's action level for radon and what does it mean?.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: Fix the home at 4 pCi/L (about 150 Bq/m3) or above; consider a fix between 2 and 4 pCi/L.

  Checked Oct 11, 2026 · https://www.epa.gov/radon/what-epas-action-level-radon-and-what-does-it-mean

• Korea JoongAng Daily. Radon in homes boosts cancer risk.

  News report: second-hand; we look for the original source.

  What we use: Korea's indoor radon standard is 148 Bq/m3 (4 pCi/L). A news report; replace with the Korean ministry page when found.

  Checked Oct 11, 2026 · https://www.koreajoongangdaily.com/korea/radon-in-homes-boosts-cancer-risk/11729996

• Michie, van Stralen and West (2011). The behaviour change wheel: a new method for characterising and designing behaviour change interventions.

  Review: experts read and summed up the research.

  What we use: Behavior depends on capability, opportunity and motivation (COM-B); change one of the three to change the behavior.

  Checked Oct 11, 2026 · https://doi.org/10.1186/1748-5908-6-42 · DOI 10.1186/1748-5908-6-42 · PubMed 21513547

• Michie and colleagues (2009). Effective techniques in healthy eating and physical activity interventions: a meta-regression.

  Pooled analysis of many studies, 122 evaluations, 44,747 people: an average across studies; only as good as the studies inside.

  What we use: Programs that had people keep track of their own behavior, plus one related technique, worked better than programs that didn't.

  Checked Oct 11, 2026 · https://doi.org/10.1037/a0016136 · DOI 10.1037/a0016136 · PubMed 19916637

• Harkin and colleagues (2016). Does monitoring goal progress promote goal attainment? A meta-analysis of the experimental evidence.

  Pooled analysis of many studies, 138 studies, 19,951 people: an average across studies; only as good as the studies inside.

  What we use: Checking progress helped people reach goals, more so when the progress was written down.

  Checked Oct 11, 2026 · https://doi.org/10.1037/bul0000025 · DOI 10.1037/bul0000025 · PubMed 26479070

• Lally and colleagues (2010). How are habits formed: modelling habit formation in the real world.

  Single study, 82 people over 12 weeks: one group of people; results may not repeat elsewhere.

  What we use: A new daily habit took 66 days on average to feel automatic, from 18 days to a projected 254; missing one day made little difference.

  Checked Oct 11, 2026 · https://doi.org/10.1002/ejsp.674 · DOI 10.1002/ejsp.674

• Gollwitzer and Sheeran (2006). Implementation intentions and goal achievement: a meta-analysis of effects and processes.

  Pooled analysis of many studies: an average across studies; only as good as the studies inside.

  What we use: Plans written as 'when X happens, I will do Y' helped people follow through on their goals.

  Checked Oct 11, 2026 · https://doi.org/10.1016/S0065-2601(06)38002-1 · DOI 10.1016/S0065-2601(06)38002-1

• Akl and colleagues (Cochrane) (2011). Using alternative statistical formats for presenting risks and risk reductions.

  Systematic review, 35 studies: pulls together every study it could find on one question.

  What we use: People understood natural frequencies ('3 in 100') better than percentages or probabilities; relative changes looked bigger and more persuasive than absolute ones.

  Checked Oct 11, 2026 · https://doi.org/10.1002/14651858.CD006776.pub2 · DOI 10.1002/14651858.CD006776.pub2 · PubMed 21412897

• US Centers for Disease Control and Prevention. CDC Clear Communication Index.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: A scored checklist for public health writing: main message, behavior advice, numbers, and how risk is explained.

  Checked Oct 11, 2026 · https://www.cdc.gov/ccindex/index.html

• US Substance Abuse and Mental Health Services Administration. 988 Suicide & Crisis Lifeline.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: In the US, call or text 988 in a crisis.

  Checked Oct 11, 2026 · https://www.samhsa.gov/mental-health/988

• The Korea Herald (2026). Korea's 109 suicide prevention hotline.

  News report: second-hand; we look for the original source.

  What we use: In Korea, 109 is the government's 24-hour suicide prevention line; callers can ask for an English translator. A news report; replace with the ministry page when found.

  Checked Oct 11, 2026 · https://www.koreaherald.com/article/10759801

• The Nobel Assembly at Karolinska Institutet (2026). Press release: The Nobel Prize in Physiology or Medicine 2026.

  Official announcement: what an organization said about its own decision; not a study.

  What we use: The 2026 prize went to Karl Deisseroth, Peter Hegemann and Georg Nagel "for their discoveries concerning light-gated ion channels and optogenetics". Hegemann and Nagel found channelrhodopsin in a single-celled alga; Deisseroth made it a light-controlled switch for nerve cells.

  Checked Oct 12, 2026 · https://www.nobelprize.org/prizes/medicine/2026/press-release/

• National Institute of Standards and Technology. NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically.

  Reference table: a standard definition or unit conversion; not a finding.

  What we use: One curie is 3.7 E+10 becquerels, exactly. That makes 1 pCi/L equal to 37 Bq/m3.

  Checked Oct 11, 2026 · https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8

• US Environmental Protection Agency. Carbon monoxide's impact on indoor air quality.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: CO alarms on each level outside each sleeping area (citing CPSC); a vented exhaust fan over gas stoves; yearly professional check of heating; never a portable generator or idling car indoors or in a garage.

  Checked Oct 12, 2026 · https://www.epa.gov/indoor-air-quality-iaq/carbon-monoxides-impact-indoor-air-quality

• US Centers for Disease Control and Prevention. About secondhand smoke.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: There is no safe level of exposure to secondhand smoke; eliminating smoking is the only way to fully protect people from it.

  Checked Oct 12, 2026 · https://www.cdc.gov/tobacco/secondhand-smoke/about.html

• US Environmental Protection Agency. Reduce the risk of lead exposure at home.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: Homes built before 1978 are more likely to have lead-based paint; wipe peeling or chipping paint with a wet cloth, fix small areas soon without sanding, and leave paint removal to a certified professional.

  Checked Oct 12, 2026 · https://www.epa.gov/lead/protect-your-family-sources-lead

• US Food and Drug Administration. Advice about eating fish.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: For people who are or may become pregnant or are breastfeeding, and children 1 to 11: choose fish lower in mercury from the Best Choices list (such as salmon, shrimp, cod, tilapia); avoid shark, swordfish, king mackerel and bigeye tuna.

  Checked Oct 12, 2026 · https://www.fda.gov/food/consumers/advice-about-eating-fish

• US Centers for Disease Control and Prevention. Guidelines for testing well water.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: Test private well water at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH, and ask the local health department what else to test for.

  Checked Oct 12, 2026 · https://www.cdc.gov/drinking-water/safety/guidelines-for-testing-well-water.html

• US Environmental Protection Agency. A brief guide to mold, moisture and your home.

  Health agency advice: what a public health body recommends; check the page for its own sources.

  What we use: The key to mold control is moisture control: fix leaks, dry wet areas within 24 to 48 hours, keep indoor humidity below 60% (ideally 30 to 50%); for mold over about 10 square feet, follow EPA's remediation guidance.

  Checked Oct 12, 2026 · https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home