Longevity Basics

Beyond the book

Multivitamins, vitamin D, and fish oil for an aging brain

Longevity Basics leaves out supplements on purpose: the six factors have stronger evidence, and supplement research changes fast. We track it here instead, so we can update it as new trials appear.

Sources

Every source in the book

1. ADA
   ADA (American Diabetes Association Professional Practice Committee for Diabetes). 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S27–S49. doi:10.2337/dc26-S002.
   Source of the fasting glucose and HbA1c categories (unchanged from earlier editions); “fasting” means no caloric intake for at least 8 hours. (Chapter 3, Appendices A and C, Figure 11)
2. Alimujiang
   Alimujiang A, Wiensch A, Boss J, et al. Association Between Life Purpose and Mortality Among US Adults Older Than 50 Years. JAMA Network Open. 2019;2(5):e194270. doi:10.1001/jamanetworkopen.2019.4270.
   Cohort of 6,985 U.S. adults over 50 followed about four years, with purpose measured by a 7-item questionnaire; those with the weakest sense of purpose had 2.43 times the risk of death of those with the strongest. Observational; see Sias & Turtle (2026). (Chapter 6)
3. Balban
   Balban MY, Neri E, Kogon MM, et al. Brief Structured Respiration Practices Enhance Mood and Reduce Physiological Arousal. Cell Reports Medicine. 2023;4(1):100895. doi:10.1016/j.xcrm.2022.100895.
   One-month randomized study of 108 volunteers doing 5 minutes a day: breathwork, especially cyclic sighing, improved mood and lowered breathing rate more than mindfulness meditation. (Chapter 5)
4. Bauer
   Bauer J, Biolo G, Cederholm T, et al. Evidence-Based Recommendations for Optimal Dietary Protein Intake in Older People: A Position Paper From the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542–559. doi:10.1016/j.jamda.2013.05.021.
   Recommends at least 1.0–1.2 g of protein per kg of body weight daily for healthy adults over 65. (Chapter 1)
5. Blumenthal
   Blumenthal RS, Morris PB, Gaudino M, et al. 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Dyslipidemia: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2026;153(17):e1154–e1276. doi:10.1161/CIR.0000000000001423.
   The current U.S. cholesterol guideline; it replaces the 2018 guideline. Sets LDL cholesterol goals by risk level (below 100, 70, or 55 mg/dL) and suggests ApoB testing mainly once LDL and non-HDL goals are met, especially in people with heart disease, diabetes, or high triglycerides, to guide further treatment. (Chapter 3, Appendix C, Figure 11)
6. Born
   Born J, Hansen K, Marshall L, Mölle M, Fehm HL. Timing the End of Nocturnal Sleep. Nature. 1999;397(6714):29–30. doi:10.1038/16166.
   People who expected to be woken at a set time showed a marked rise in ACTH, the hormone that triggers cortisol, about an hour before waking. (Chapter 4)
7. Bouchard
   Bouchard C, An P, Rice T, et al. Familial Aggregation of VO2max Response to Exercise Training: Results From the HERITAGE Family Study. J Appl Physiol. 1999;87(3):1003–1008. doi:10.1152/jappl.1999.87.3.1003.
   481 sedentary adults from 98 families trained for 20 weeks; gains ranged from little or none to more than 1 liter a minute, with a maximal heritability estimate of 47% for the response. (Chapter 2)
8. Cappuccio
   Cappuccio FP, D’Elia L, Strazzullo P, Miller MA. Sleep Duration and All-Cause Mortality: A Systematic Review and Meta-Analysis of Prospective Studies. Sleep. 2010;33(5):585–592. doi:10.1093/sleep/33.5.585.
   16 studies, about 1.4 million people: habitually short sleep was linked to a 12% higher risk of death and long sleep to a 30% higher risk. (Chapter 4)
9. CDC
   CDC (Centers for Disease Control and Prevention). About Older Adult Fall Prevention. Last updated September 4, 2026. cdc.gov/falls/about/index.html.
   Falls are the leading cause of injury death among adults 65 and older, with more than 43,000 deaths in 2024. (Chapter 1)
10. Cleveland Clinic 2023
    Cleveland Clinic. Sleep: What It Is, Why It’s Important, Stages, REM & NREM. June 19, 2023. my.clevelandclinic.org/health/articles/12148-sleep-basics.
    Typical adult shares of the sleep stages: about 5% N1, 45% N2, 25% N3 (deep sleep), and 25% REM; most people go through four or five cycles a night. (Figure 12)
11. Cleveland Clinic 2025
    Cleveland Clinic. What To Know About Exercise and Heart Rate Zones. Health Essentials. October 6, 2025. health.clevelandclinic.org.
    Describes five heart rate zones as percentages of maximum (50–60%, 60–70%, 70–80%, 80–90%, 90–100%) and notes that the 220-minus-age formula is only an estimate. (Chapter 2, Figure 6)
12. DeFronzo
    DeFronzo RA, Tripathy D. Skeletal Muscle Insulin Resistance Is the Primary Defect in Type 2 Diabetes. Diabetes Care. 2009;32(Suppl 2):S157–S163. doi:10.2337/dc09-S302.
    During an insulin clamp (high insulin, normal blood sugar), skeletal muscle took up about 80–90% of the infused glucose. (Chapter 1)
13. Depner
    Depner CM, Melanson EL, Eckel RH, et al. Ad libitum Weekend Recovery Sleep Fails to Prevent Metabolic Dysregulation during a Repeating Pattern of Insufficient Sleep and Weekend Recovery Sleep. Current Biology. 2019;29(6):957–967.e4. doi:10.1016/j.cub.2019.01.069.
    Controlled lab study: adults given 5-hour sleep opportunities on weeknights who slept in on weekends still lost about 9–27% of insulin sensitivity (whole-body, liver, and muscle measures), and insufficient sleep increased after-dinner eating. (Chapter 4)
14. Drake
    Drake C, Roehrs T, Shambroom J, Roth T. Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed. Journal of Clinical Sleep Medicine. 2013;9(11):1195–1200. doi:10.5664/jcsm.3170.
    12 healthy sleepers: 400 mg of caffeine taken six hours before bed reduced objectively measured sleep by more than an hour; sleep diaries didn’t clearly detect the loss. (Chapter 4)
15. Ebrahim
    Ebrahim IO, Shapiro CM, Williams AJ, Fenwick PB. Alcohol and Sleep I: Effects on Normal Sleep. Alcoholism: Clinical and Experimental Research. 2013;37(4):539–549. doi:10.1111/acer.12006.
    Review: alcohol shortens the time to fall asleep, delays REM sleep and reduces it at moderate and high doses, and disrupts the second half of the night. (Chapter 4)
16. Eide
    Eide PK, Vinje V, Pripp AH, Mardal KA, Ringstad G. Sleep Deprivation Impairs Molecular Clearance From the Human Brain. Brain. 2021;144(3):863–874. doi:10.1093/brain/awaa443.
    Small, non-randomized study of 24 patients: one night without sleep slowed clearance of an MRI tracer from most brain regions. (Chapter 4)
17. Epel
    Epel ES, Blackburn EH, Lin J, et al. Accelerated Telomere Shortening in Response to Life Stress. Proc Natl Acad Sci USA. 2004;101(49):17312–17315. doi:10.1073/pnas.0407162101.
    58 mothers: the most stressed had telomeres shorter by the equivalent of at least a decade (an estimated 9–17 years) of additional aging. Cross-sectional. (Introduction, Chapter 5)
18. FDA
    FDA (U.S. Food and Drug Administration). Spilling the Beans: How Much Caffeine Is Too Much? Updated August 28, 2024. fda.gov.
    400 mg of caffeine is about two to three 12-ounce cups of coffee. (Chapter 4)
19. Fiatarone
    Fiatarone MA, Marks EC, Ryan ND, et al. High-Intensity Strength Training in Nonagenarians: Effects on Skeletal Muscle. JAMA. 1990;263(22):3029–3034. doi:10.1001/jama.1990.03440220053029.
    Ten frail nursing-home residents averaging 90 years old began eight weeks of high-intensity resistance training; in the nine who completed it, strength rose an average of 174%. (Introduction, Chapter 1, FAQ)
20. Gill
    Gill S, Panda S. A Smartphone App Reveals Erratic Diurnal Eating Patterns in Humans that Can Be Modulated for Health Benefits. Cell Metabolism. 2015;22(5):789–798. doi:10.1016/j.cmet.2015.09.005.
    App-based study of 156 healthy adults: more than half ate over a span of 15 hours or longer each day. (Chapter 3)
21. Gollwitzer
    Gollwitzer PM, Sheeran P. Implementation Intentions and Goal Achievement: A Meta-analysis of Effects and Processes. Advances in Experimental Social Psychology. 2006;38:69–119. doi:10.1016/S0065-2601(06)38002-1.
    94 independent tests with 8,461 participants: planning when, where, and how to act (“if-then” plans) had a medium-to-large effect on reaching goals (d = 0.65). (How to Use This Book)
22. Goyal
    Goyal M, Singh S, Sibinga EMS, et al. Meditation Programs for Psychological Stress and Well-being: A Systematic Review and Meta-analysis. JAMA Internal Medicine. 2014;174(3):357–368. doi:10.1001/jamainternmed.2013.13018.
    47 trials, 3,515 participants: mindfulness programs modestly improved anxiety, depression, and pain; there was no evidence that meditation programs worked better than other active treatments such as exercise. (Chapter 5)
23. Hall
    Hall JA. How Many Hours Does It Take to Make a Friend? Journal of Social and Personal Relationships. 2019;36(4):1278–1296. doi:10.1177/0265407518761225.
    Estimated roughly 40–60 hours together to form a casual friendship and 200 or more for a close one. (Chapter 6)
24. Halling
    Halling JF, Pilegaard H. Autophagy-Dependent Beneficial Effects of Exercise. Cold Spring Harbor Perspectives in Medicine. 2017;7(8):a029777. doi:10.1101/cshperspect.a029777.
    Review: robust evidence that autophagy is stimulated in skeletal muscle by a bout of endurance exercise, though results vary with the type and length of exercise. (Chapter 3)
25. Helgerud
    Helgerud J, Høydal K, Wang E, et al. Aerobic High-Intensity Intervals Improve VO2max More Than Moderate Training. Medicine & Science in Sports & Exercise. 2007;39(4):665–671. doi:10.1249/mss.0b013e3180304570.
    Eight-week randomized trial in 40 moderately trained young men (55 recruited) running on a treadmill, all groups doing the same total work: VO2 max rose 7.2% with 4x4 intervals and 5.5% with 15/15 intervals; steady training at 70% or 85% of max heart rate showed no apparent change. (Chapter 2, Figures 7 and 8)
26. HHS
    HHS (U.S. Department of Health and Human Services). Physical Activity Guidelines for Americans, 2nd edition. Washington, DC: HHS; 2018.
    Recommends muscle-strengthening activity for all major muscle groups on two or more days a week. Lists lower risk of Type 2 diabetes, improved sleep, reduced anxiety, improved bone health, and, in older adults, lower risk of falls and fall injuries among the benefits of regular physical activity. Still the current edition in 2026. (Introduction, Chapters 1, 4, and 5)
27. Holt-Lunstad
    Holt-Lunstad J, Smith TB, Layton JB. Social Relationships and Mortality Risk: A Meta-analytic Review. PLoS Medicine. 2010;7(7):e1000316. doi:10.1371/journal.pmed.1000316.
    148 studies, 308,849 participants: stronger social relationships were associated with a 50% greater likelihood of survival, an effect the authors judged comparable to quitting smoking and larger than obesity or physical inactivity. Observational. (Introduction, Chapter 6)
28. Labcorp
    Labcorp. Insulin (test 004333) and Labcorp Specialty Testing, Insulin (test 503068): reference intervals. Checked September 2026. labcorp.com; specialtytesting.labcorp.com.
    Test 004333 lists 2.6–24.9 µIU/mL; specialty test 503068 lists 17 µIU/mL or less for fasting adults. Different methods give different ranges. (Chapter 3, Appendices A and C, Figure 11)
29. Laborde
    Laborde S, Allen MS, Borges U, et al. Effects of Voluntary Slow Breathing on Heart Rate and Heart Rate Variability: A Systematic Review and a Meta-analysis. Neuroscience & Biobehavioral Reviews. 2022;138:104711. doi:10.1016/j.neubiorev.2022.104711.
    223 studies: slow breathing increased vagally mediated heart rate variability during and after practice. (Introduction, Chapter 5)
30. Lally
    Lally P, van Jaarsveld CHM, Potts HWW, Wardle J. How Are Habits Formed: Modelling Habit Formation in the Real World. European Journal of Social Psychology. 2010;40(6):998–1009. doi:10.1002/ejsp.674.
    96 volunteers repeated a new daily behavior for 12 weeks. Among those whose data fit the model, the median time to automaticity was 66 days, with estimates from 18 to 254 days; missing one day didn’t materially affect habit formation. (Introduction, Chapter 7)
31. Leong
    Leong DP, Teo KK, Rangarajan S, et al. Prognostic Value of Grip Strength: Findings From the Prospective Urban Rural Epidemiology (PURE) Study. The Lancet. 2015;386(9990):266–273. doi:10.1016/S0140-6736(14)62000-6.
    139,691 adults aged 35–70 in 17 countries: each 5 kg lower grip strength was associated with a 16% higher risk of death from any cause, a 17% higher risk of cardiovascular death, and a 7% higher risk of heart attack. Observational. (Introduction)
32. Levine
    Levine B, Kroemer G. Biological Functions of Autophagy Genes: A Disease Perspective. Cell. 2019;176(1–2):11–42. doi:10.1016/j.cell.2018.09.048.
    Review linking defects in autophagy genes to neurodegenerative and inflammatory diseases, cancer, and aging. (Chapter 3)
33. Liu 2022
    Liu D, Huang Y, Huang C, et al. Calorie Restriction with or without Time-Restricted Eating in Weight Loss. N Engl J Med. 2022;386(16):1495–1504. doi:10.1056/NEJMoa2114833.
    139 adults with obesity, 12 months: adding an 8-hour eating window to a lower-calorie diet was not more beneficial for weight, body fat, or metabolic risk factors than the diet alone. (Chapter 3)
34. Liu 2023
    Liu PJ, Rim S, Min L, Min KE. The Surprise of Reaching Out: Appreciated More Than We Think. Journal of Personality and Social Psychology. 2023;124(4):754–771. doi:10.1037/pspi0000402.
    Across preregistered experiments, people consistently underestimated how much others appreciated being reached out to. (Chapter 6)
35. Mandsager
    Mandsager K, Harb S, Cremer P, et al. Association of Cardiorespiratory Fitness With Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing. JAMA Network Open. 2018;1(6):e183605. doi:10.1001/jamanetworkopen.2018.3605.
    122,007 adults referred for treadmill testing; elite fitness (top 2.3%) vs. low fitness (bottom 25%): adjusted hazard ratio 0.20, about 80% lower risk of death over a median 8.4 years, with similar findings in men and women. The risk of low fitness was comparable to or greater than smoking, diabetes, or coronary artery disease. Observational. (Introduction, Chapter 2)
36. McEwen
    McEwen BS. Protective and Damaging Effects of Stress Mediators. N Engl J Med. 1998;338(3):171–179. doi:10.1056/NEJM199801153380307.
    Review of “allostatic load”: long-term stress-hormone exposure linked to abdominal fat, high blood pressure, insulin resistance, weaker immune responses, and memory effects. (Chapter 5)
37. Miao
    Miao A, Luo T, Hsieh B, et al. Brain Clearance Is Reduced During Sleep and Anesthesia. Nature Neuroscience. 2024;27(6):1046–1050. doi:10.1038/s41593-024-01638-y.
    In mice, found brain clearance reduced, not increased, during sleep and anesthesia; other researchers disputed the finding in 2025. (Chapter 4)
38. Milanović
    Milanović Z, Sporiš G, Weston M. Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials. Sports Medicine. 2015;45(10):1469–1481. doi:10.1007/s40279-015-0365-0.
    28 studies, 723 young adults: both steady endurance training and intervals raised VO2 max substantially, intervals slightly more; people with lower starting fitness gained more. (Chapter 2)
39. Morton
    Morton RW, Murphy KT, McKellar SR, et al. A Systematic Review, Meta-Analysis and Meta-Regression of the Effect of Protein Supplementation on Resistance Training-Induced Gains in Muscle Mass and Strength in Healthy Adults. Br J Sports Med. 2018;52(6):376–384. doi:10.1136/bjsports-2017-097608.
    49 trials, 1,863 participants: gains in fat-free mass leveled off at about 1.6 g of protein per kg per day. (Chapter 1)
40. NCCIH
    NCCIH (National Center for Complementary and Integrative Health). Melatonin: What You Need To Know. Last updated May 2024. nccih.nih.gov.
    Not enough strong evidence to recommend melatonin for chronic insomnia; some evidence for jet lag; product labels often don’t match contents; short-term use appears safe for most people. (Chapter 4)
41. NCEP ATP III
    NCEP ATP III (National Cholesterol Education Program Expert Panel). Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) Final Report. Circulation. 2002;106(25):3143–3421. doi:10.1161/circ.106.25.3143.
    Source of the LDL, HDL, and triglyceride categories still printed on many lab reports and of the metabolic syndrome definition (three or more of five risk factors, which together enhance heart-disease risk); its treatment advice has been replaced by later guidelines. (Appendix C)
42. NHLBI
    NHLBI (National Heart, Lung, and Blood Institute). What Is Sleep Apnea? Updated January 9, 2025. nhlbi.nih.gov.
    Sleep apnea is a common condition; untreated, it increases the risk of stroke, heart attack, and other serious problems. (Chapter 4)
43. Ohayon
    Ohayon MM, Carskadon MA, Guilleminault C, Vitiello MV. Meta-Analysis of Quantitative Sleep Parameters From Childhood to Old Age in Healthy Individuals: Developing Normative Sleep Values Across the Human Lifespan. Sleep. 2004;27(7):1255–1273. doi:10.1093/sleep/27.7.1255.
    In adults, the shares of deep (slow-wave) sleep and REM sleep decrease with age. (Figure 12)
44. Pearson
    Pearson TA, Mensah GA, Alexander RW, et al. Markers of Inflammation and Cardiovascular Disease: Application to Clinical and Public Health Practice: A Statement for Healthcare Professionals From the Centers for Disease Control and Prevention and the American Heart Association. Circulation. 2003;107(3):499–511. doi:10.1161/01.CIR.0000052939.59093.45.
    Source of the hs-CRP risk categories; advises averaging two tests and repeating any result above 10 mg/L. (Chapter 3, Appendix C, Figure 11)
45. Reed
    Reed JL, Pipe AL. The Talk Test: A Useful Tool for Prescribing and Monitoring Exercise Intensity. Current Opinion in Cardiology. 2014;29(5):475–480. doi:10.1097/HCO.0000000000000097.
    Review: comfortable speech is likely possible below the ventilatory or lactate threshold and not likely above it. (Chapter 2)
46. Saner
    Saner NJ, Lee MJ-C, Pitchford NW, et al. The Effect of Sleep Restriction, With or Without High-Intensity Interval Exercise, on Myofibrillar Protein Synthesis in Healthy Young Men. J Physiol. 2020;598(8):1523–1536. doi:10.1113/JP278828.
    24 young men: five nights of 4 hours in bed lowered muscle protein synthesis by about a fifth compared with normal sleep; interval exercise prevented the drop. (Chapter 1)
47. Schoenfeld 2016
    Schoenfeld BJ, Ogborn D, Krieger JW. Effects of Resistance Training Frequency on Measures of Muscle Hypertrophy: A Systematic Review and Meta-Analysis. Sports Medicine. 2016;46(11):1689–1697. doi:10.1007/s40279-016-0543-8.
    Training each muscle group at least twice a week produced more growth than once a week. (Chapter 1)
48. Schoenfeld 2019
    Schoenfeld BJ, Grgic J, Krieger J. How Many Times per Week Should a Muscle Be Trained to Maximize Muscle Hypertrophy? A Systematic Review and Meta-Analysis of Studies Examining the Effects of Resistance Training Frequency. J Sports Sci. 2019;37(11):1286–1295. doi:10.1080/02640414.2018.1555906.
    When total weekly training volume was equal, higher and lower training frequencies produced similar muscle growth. (Chapter 1)
49. Seiler
    Seiler KS, Kjerland GØ. Quantifying Training Intensity Distribution in Elite Endurance Athletes: Is There Evidence for an “Optimal” Distribution? Scand J Med Sci Sports. 2006;16(1):49–56. doi:10.1111/j.1600-0838.2004.00418.x.
    11 well-trained junior cross-country skiers: about 75% of training sessions were at low intensity and 15–20% hard, with little in between. (Chapter 2)
50. Sias
    Sias R, Turtle H. The Importance of Baseline Health in Linking Life Purpose to Longevity. PLoS One. 2026;21(5):e0349401. doi:10.1371/journal.pone.0349401.
    Re-analysis of the Health and Retirement Study data behind Alimujiang et al. (2019): with better adjustment for health at the start, the link between purpose and mortality weakened and was no longer statistically clear. (Chapter 6)
51. Sleep Foundation
    Sleep Foundation. Best Temperature for Sleep. Updated July 11, 2025. sleepfoundation.org.
    Recommends about 65°F and notes that most doctors recommend 65 to 68°F for sleep. (Chapter 4)
52. Srikanthan
    Srikanthan P, Karlamangla AS. Relative Muscle Mass Is Inversely Associated With Insulin Resistance and Prediabetes. Findings From the Third National Health and Nutrition Examination Survey. J Clin Endocrinol Metab. 2011;96(9):2898–2903. doi:10.1210/jc.2011-0435.
    13,644 U.S. adults: more muscle relative to body size was associated with better insulin sensitivity and less prediabetes. Cross-sectional. (Chapter 1)
53. Sutton
    Sutton EF, Beyl R, Early KS, et al. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even Without Weight Loss in Men With Prediabetes. Cell Metabolism. 2018;27(6):1212–1221.e3. doi:10.1016/j.cmet.2018.04.010.
    Small five-week crossover trial in men with prediabetes: a 6-hour eating window ending in mid-afternoon improved insulin sensitivity compared with a 12-hour window. (Chapter 3)
54. Twohig-Bennett
    Twohig-Bennett C, Jones A. The Health Benefits of the Great Outdoors: A Systematic Review and Meta-Analysis of Greenspace Exposure and Health Outcomes. Environmental Research. 2018;166:628–637. doi:10.1016/j.envres.2018.06.030.
    143 studies: more greenspace exposure was associated with lower salivary cortisol and a slightly lower heart rate; study quality varied, and many studies were of Japanese forest bathing. (Chapter 5)
55. Van Cauter
    Van Cauter E, Plat L. Physiology of Growth Hormone Secretion During Sleep. J Pediatr. 1996;128(5 Pt 2):S32–S37. doi:10.1016/S0022-3476(96)70008-2.
    In adults, the growth-hormone pulse soon after sleep onset, during deep sleep, is often the day’s largest. (Chapter 4)
56. Verduyn
    Verduyn P, Lee DS, Park J, et al. Passive Facebook Usage Undermines Affective Well-Being: Experimental and Longitudinal Evidence. J Exp Psychol Gen. 2015;144(2):480–488. doi:10.1037/xge0000057.
    Two studies of college students: passive Facebook use lowered moment-to-moment well-being, largely by increasing envy. (Chapter 6)
57. Volpi
    Volpi E, Nazemi R, Fujita S. Muscle Tissue Changes With Aging. Curr Opin Clin Nutr Metab Care. 2004;7(4):405–410. doi:10.1097/01.mco.0000134362.76653.b2.
    Review: muscle mass declines an estimated 3–8% per decade after 30, faster after 60. (Chapter 1, Figure 3)
58. Wang
    Wang Z, Ying Z, Bosy-Westphal A, et al. Specific Metabolic Rates of Major Organs and Tissues Across Adulthood: Evaluation by Mechanistic Model of Resting Energy Expenditure. Am J Clin Nutr. 2010;92(6):1369–1377. doi:10.3945/ajcn.2010.29885.
    Found the standard resting rates of about 13 kcal/kg/day for muscle and 4.5 for fat (about 6 and 2 kcal per pound) held for young and middle-aged adults; for adults over 50 they ran about 3% high. (Chapter 1)
59. Watson 2015
    Watson NF, Badr MS, Belenky G, et al. Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society. J Clin Sleep Med. 2015;11(6):591–592. doi:10.5664/jcsm.4758.
    Adults should sleep 7 or more hours a night; regularly sleeping less is associated with weight gain, diabetes, high blood pressure, heart disease and stroke, depression, a higher risk of death, and impaired immune function. (Chapter 4)
60. Watson 2018
    Watson SL, Weeks BK, Weis LJ, et al. High-Intensity Resistance and Impact Training Improves Bone Mineral Density and Physical Function in Postmenopausal Women With Osteopenia and Osteoporosis: The LIFTMOR Randomized Controlled Trial. J Bone Miner Res. 2018;33(2):211–220. doi:10.1002/jbmr.3284.
    101 postmenopausal women with low bone mass: eight months of supervised heavy strength and impact training twice a week improved spine bone density and maintained hip bone density, while a low-intensity home group lost bone. (Chapter 1)
61. Windred
    Windred DP, Burns AC, Lane JM, et al. Sleep Regularity Is a Stronger Predictor of Mortality Risk Than Sleep Duration: A Prospective Cohort Study. Sleep. 2024;47(1):zsad253. doi:10.1093/sleep/zsad253.
    60,977 UK Biobank participants wore activity trackers for 7 days. After full adjustment, the most regular sleepers had about 30% lower risk of death from any cause than the least regular (hazard ratio 0.70; the paper’s headline 20–48% range spans the other quintiles and a less-adjusted model), and regularity predicted mortality better than sleep duration. Observational. (Chapter 4)
62. Xie
    Xie L, Kang H, Xu Q, et al. Sleep Drives Metabolite Clearance From the Adult Brain. Science. 2013;342(6156):373–377. doi:10.1126/science.1241224.
    In mice, the space between brain cells widened by more than 60% during sleep, and beta-amyloid was cleared about twice as fast as during waking. (Chapter 4)
63. Yorks
    Yorks DM, Frothingham CA, Schuenke MD. Effects of Group Fitness Classes on Stress and Quality of Life of Medical Students. J Am Osteopath Assoc. 2017;117(11):e17–e25. doi:10.7556/jaoa.2017.140.
    Small, non-randomized 12-week study of 69 medical students: those in a weekly group fitness class reported less stress; those exercising alone showed no significant change. (Chapter 5)