What are TCM constitution, sleep cycles, and lifestyle scores?
This page is a hybrid: it pairs one tool from Traditional Chinese Medicine (the nine-constitution questionnaire, ZYYXH/T157-2009) with five tools from conventional Western epidemiology and chronobiology (China-specific BMI classification, 90-minute sleep cycles, caffeine half-life, simplified life-expectancy estimator, mid-parental child height prediction). The mix is intentional — wellness increasingly means combining both frameworks, especially in East Asian contexts where TCM operates as a parallel health system. The TCM section is a standardized self-report questionnaire developed by the China Association of Chinese Medicine and widely used in Chinese preventive-medicine clinics; the other five panels are equations that turn a handful of inputs (height, weight, age, caffeine dose) into a number with a clinical interpretation. None of the panels is a diagnostic tool; all are educational decision support.
Three vocab distinctions to keep straight: Constitution in TCM (体质) is not the same as "build" in English — it includes inherited and acquired tendencies (energy level, temperature preference, digestion, emotional baseline). China BMI uses lower cutoffs (24 / 28) than the WHO international standard (25 / 30) because Chinese populations develop cardiometabolic complications at lower BMI. Sleep cycle here is the 90-minute REM-NREM cycle, distinct from circadian rhythm (the 24-hour body clock that drives when you feel sleepy or alert). Half-life in pharmacology is the time for a drug's blood level to drop by half — caffeine's is 5 hours on average, but varies 3–7 hours by CYP1A2 genetics.
Nine-constitution identification (ZYYXH/T157-2009)
The ZYYXH/T157-2009 standard (issued by the China Association of Chinese Medicine, CACM) classifies adults into nine constitutional types: Balanced (平和质) — no significant pathology, energetic; Qi Deficiency (气虚质) — tired easily, catches colds, spontaneous sweating; Yang Deficiency (阳虚质) — cold hands/feet, sensitive to cold; Yin Deficiency (阴虚质) — hot palms/soles, dry mouth; Phlegm-Damp (痰湿质) — heavy body, oily face, abdominal bloating; Damp-Heat (湿热质) — acne, oily skin, bitter mouth; Blood Stasis (血瘀质) — easy bruising, dark complexion, fixed pain; Qi Stagnation (气郁质) — anxious, sighing, sensitive to emotions; Inherited Special (特禀质) — allergic, asthma, eczema family history. The page asks 36 questions (4 per constitution, 1–5 scale), averages each group, and reports the highest-scoring non-balanced type as the primary tendency. With the sample (Balanced 3.0 / Qi Def 4.0 / others 3.0), the result is Qi Deficiency 4.0/5 with the standard advice to eat warm, easy-to-digest foods and avoid raw/cold foods. The clinical evidence base for the nine-constitution model is mixed; it is widely used in Chinese preventive medicine but has limited Western replication studies.
China BMI — tighter thresholds than WHO
BMI = weight / height² is the same formula as in the Body Metrics page, but the classification thresholds differ. The WHO international standard uses <18.5 / 18.5–24.9 / 25–29.9 / ≥30 (underweight / normal / overweight / obese). The COTH (2001) China standard uses <18.5 / 18.5–23.9 / 24–27.9 / ≥28, because Chinese and Southeast Asian populations develop type 2 diabetes, hypertension, and metabolic syndrome at lower BMIs than Europeans — a phenomenon sometimes called the "Asian BMI paradox." With the sample (170 cm / 65 kg), BMI = 22.5 → Normal; ideal range for that height is 53.5–69.1 kg (BMI 18.5 × 1.7² to 23.9 × 1.7²). The China standard is recommended for any patient identifying as East Asian; the WHO standard is more appropriate for European, African, and Middle Eastern populations.
Sleep cycles — the 90-minute rhythm
Adult sleep cycles between REM (rapid-eye-movement, light, dream-heavy) and NREM (deep, restorative) every ~90 minutes, with cycles getting more REM-heavy toward morning. The page uses this to recommend bedtimes that wake you between cycles — waking during deep sleep produces sleep inertia (grogginess for 15–30 min), while waking at the end of a cycle feels more refreshing. The calculator adds a +14 minute fall-asleep allowance (the median time from "lights off" to actual sleep). With wake-up 7:00 AM, recommended bedtimes are: 6 cycles (9.0 hr) → 21:46, 5 cycles (7.5 hr) → 23:16, 4 cycles (6.0 hr) → 00:46, 3 cycles (4.5 hr) → 02:16. Modern sleep science treats the 90-minute number as a population average (real cycles run 70–120 minutes and vary by age, sleep stage, and individual), so the recommendations are approximate; consistent bed/wake times matter more than precise cycle alignment. Adults need 7–9 hours for cognitive performance; the 5–6-cycle targets match that range.
Caffeine — pharmacokinetic half-life
Caffeine follows first-order kinetics: at any time t, the remaining dose is dose × e^(−kt) where k = ln(2)/half-life. The average adult half-life is 5 hours (range 3–7 hours, shorter in smokers who induce CYP1A2, longer in pregnancy, oral contraceptives, or liver disease). With the sample (200 mg dose, 5-h half-life): 200 mg at 0 h, 174 mg at 1 h (87%), 152 mg at 2 h (76%), 132 mg at 3 h (66%), 115 mg at 4 h (57%), 87 mg at 6 h (44%), 66 mg at 8 h (33%), 38 mg at 12 h (19%), 7 mg at 24 h (4%). Time to ~half = the input half-life; time to <1% = half × log(100)/log(2) ≈ 33 hours with a 5-h half-life. Practical implication: a coffee at 8 AM leaves 87 mg at bedtime (10 PM) and 38 mg at 8 AM the next day — enough to disrupt adenosine receptors and hurt sleep quality. Most sleep experts recommend <200 mg after 2 PM.
Life expectancy — simplified lifestyle model
Life expectancy at birth varies dramatically by country (Japan 84, Switzerland 83, Singapore 82, USA 79, China 76, India 70, global average 73 — WHO 2023). On top of country baseline, four lifestyle modifiers are commonly used: smoking (~−10 years, most damaging single factor), regular exercise (~+2 years vs sedentary), BMI category (~−2 years overweight, ~−4 years obese), heavy alcohol (~−3 years). Women live ~5 years longer than men on average, reflecting biological (estrogen, immune function) and behavioral (risk-taking, medical care) factors. With the sample (male, 30 yr, Global 77, regular exercise +2): baseline 77 + 2 = 79 yr adjusted LE, 49 years remaining. This is a population-average model — actual life expectancy depends on genetics, healthcare access, environment, occupation, and many factors the calculator does not capture. The disclaimer in the page is appropriate: do not interpret the result as a personal prediction.
Child height prediction — mid-parental method
Adult stature is ~80% heritable, and a simple regression on parents' heights predicts the offspring target surprisingly well. The Western Tanner-Whitehouse mid-parental formula: target boy = (dad + mom)/2 + 6.5 cm; target girl = (dad + mom)/2 − 6.5 cm. The Chinese formula: boy = (dad + mom + 13)/2; girl = (dad + mom − 13)/2. Both produce the same shift because (dad+mom+13)/2 = (d+m)/2 + 6.5. The ±8.5 cm "95% range" captures ~2 standard deviations — actual adult height falls within this band for ~95% of children. With the sample (male, dad 175, mom 160): mid-parental = 167.5 cm; target = 174.0 cm; range = 165.5–182.5 cm. These formulas assume healthy nutrition, no chronic disease, normal puberty timing, and average genetic background — chronic illness, malnutrition, endocrine disorders, or delayed puberty can shift the result significantly.
Common misconceptions
- The nine-constitution types are not diagnoses. They are descriptive categories for general self-awareness — most people score moderately on several types, and the "primary" is just the highest. The advice is general wellness guidance, not treatment.
- TCM is a parallel system, not a substitute. For acute illness (infection, trauma, MI, stroke), evidence-based Western medicine is overwhelmingly more effective. TCM's strength is in chronic-condition management and preventive lifestyle framing. Do not use TCM as a substitute for emergencies.
- China BMI ≠ WHO BMI; use the right one for the population. A Chinese patient with BMI 26 is "Overweight" by China standard (clinically actionable) and only "overweight borderline" by WHO. The China threshold reflects real cardiovascular risk differences.
- The 90-minute sleep cycle is approximate. Real cycles run 70–120 minutes and shift with age (shorter in elderly). Consistent bed/wake times matter more than precise cycle alignment, and individual variation is wide.
Related tools: Body Metrics for the international (WHO) BMI and body-fat context, Nutrition & Diet for the calorie and protein context behind BMI and lifestyle scoring, and Blood & Genetics for the ABO blood-type dimension of the topic that TCM sometimes references.
