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Generation Health
Shift Health Calculator
Before you continue — please read:
This platform provides health education and information only. It is not a medical service, does not provide medical advice, and does not establish a physician-patient relationship.
This calculator provides educational risk awareness for shift workers. It is not a clinical risk assessment or diagnostic tool.
No personal health data is collected or stored. AI-generated content may contain errors — verify independently.
🔒 Privacy: No account required. No name, email, or IP address collected. Anonymous usage data only, with your consent.
Estimate your circadian disruption exposure and cardiovascular health indicators — Generation Health
🔢 Shift Health Calculator
Before you start
This calculator estimates your circadian disruption exposure and, optionally, your cardiovascular health indicators. Please read before using.
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Educational estimates only. The Circadian Disruption Index (CDI) and any cardiovascular figures shown are educational scoring tools informed by published research — not validated clinical instruments and not diagnoses.
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Nothing is saved. All inputs are processed entirely in your browser. No data is stored or transmitted.
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Discuss results with your provider. Use this as a starting point for a conversation — not as a clinical decision.
Generation Health · Shift Health MAP
Shift Health Calculator
Enter your shift pattern to estimate your Circadian Disruption Index. Optionally add your lab results for a cardiovascular health picture.
This is an educational awareness tool, not a medical assessment. Results do not constitute medical advice. By starting, you acknowledge this.
Enter your shift details below. Results appear as you type — nothing is saved or uploaded.
✓ We've pre-filled this from your assessment responses — adjust any values if needed.
Your shift pattern
Night shifts per month From assessment
How many night shifts do you work each month? A night shift includes hours between midnight and 6am.
0
shifts / month
Typical shift length From assessment
How long is a typical shift? Include any overtime you regularly work.
Years working shifts From assessment
Total years in any shift work role. Includes all past jobs.
years
Quick returns / month From assessment
Times with less than 11 h between shifts. e.g. finish at 7am, back at 5pm.
0
Max consecutive nights in a row From assessment
What's the most night shifts you work back-to-back? Tap to select.
Circadian biology
Social jetlag (hours)
How many hours later do you wake up on days off vs. workdays? e.g. 7am on workdays, 10am off = 3 hrs. Each hour of social jetlag is linked to >30% higher cardiovascular risk.
0
hours difference
Your natural body clock (chronotype)
Without work commitments, when do you naturally feel most alert? Evening chronotype in shift workers independently elevates cardiometabolic risk.
Educational use only. CVD risk figures below use the 2013 ACC/AHA Pooled Cohort Equations, which were derived from US populations and may not fully represent all Canadian or international patients. The shift-adjusted figure applies a 23% relative risk increase from Vyas et al., 2012 (BMJ) — this is not a validated shift-specific equation. Discuss all results with your provider before making any health decisions.
Age (years)
PCE validated age 40–79 · PREVENT age 30–79
Sex assigned at birth
Used for published PCE equations · not a value judgment
Total Cholesterol (mmol/L)
mmol/L · normal: 2.0–5.2
HDL Cholesterol (mmol/L)
mmol/L · optimal: >1.0 (F) / >0.9 (M)
Systolic BP (mmHg)
top number · optimal: <120
On BP medication?
Current smoker?
Diabetes diagnosis?
Optional — shift-work specific biomarkers
If you have these values, adding them unlocks your TyG index (insulin resistance marker) and TG:HDL ratio — both specifically elevated in shift workers.
Triglycerides (mmol/L)
optimal: <1.7 mmol/L
Fasting Glucose (mmol/L)
optimal: <5.6 mmol/L
10-year CVD Risk
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Based on your lab values alone (ACC/AHA PCE)
Shift-Adjusted Estimate
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+23% relative risk for shift workers · Vyas 2012
Your Circadian Load Estimate
Circadian Load Tier
CDI Score
FlourishingNurtureRoom to Grow
Night hours / month
hours of night work each month
Shifts / year
estimated night shifts annually
Cumulative lifetime night exposure
hours
0 years10+ years = elevated risk threshold
Menopause: Rotating night shifts ≥20 months are associated with 25% higher risk of early menopause (before age 45). Perimenopausal shift workers report greater difficulty managing symptoms at work — hot flushes, insomnia, and mood disruption are compounded by circadian disruption. Hormonal health monitoring is a supported discussion with your provider. Stock et al., 2019 — Human Reproduction; Atkinson et al., 2025 — Maturitas
Currently pregnant: Consensus recommends ≤1 night shift per week during pregnancy. Rotating night work is associated with higher rates of miscarriage, preterm birth, low birth weight, and gestational hypertension. Early GDM screening (first trimester rather than 24–28 weeks) is worth discussing with your provider. Do not use overnight fasting protocols while pregnant. Garde et al., 2020 — Scand J Work Environ Health; Cesta et al., 2024
Planning pregnancy: Shift work is associated with longer time to conceive and menstrual irregularity from HPG axis disruption. A full preconception assessment is evidence-supported before trying to conceive. The Generation Health PPC Platform covers all 10 preconception health domains relevant to shift workers. Male shift work also affects sperm quality. Garde et al., 2020; Vetter et al., 2016 — JAMA
Your quick wins — leave with answers
This tool does not engage in the practice of medicine. It does not diagnose any condition, prescribe any treatment, or direct any clinical action. Results are educational estimates only — discuss all findings with your healthcare provider.
⚕ The Circadian Disruption Index (CDI) is an educational scoring formula informed by Vyas et al. 2012 (BMJ), Torquati et al. 2018 (Scand J Work Environ Health), Gamboa Madeira et al. 2021 (J Sleep Research), and Wanigasinghe et al. 2025 (Br J Nutr). CVD risk estimates use the 2013 ACC/AHA Pooled Cohort Equations (PCE; Goff et al., 2014 JACC), the current standard with real-world c-stat 0.78. Note: The 2023 AHA PREVENT equations are newer (race-free, age 30–79, includes eGFR/BMI) but systematically estimate lower risk than PCE; disclosure provided in results. Shift-adjusted figures: ×1.17 overall CVD (Ho et al., 2022 Int J Epidemiol, n=238,661); ×1.23 MI (Vyas et al., 2012 BMJ); +7.1%/5 yrs duration (Torquati 2018); ×1.1 women (Vetter et al., 2016 JAMA). TyG cutoffs: Guerrero-Romero 2010 JCEM (4.68 IR) and Mavraganis 2025 DOM (8.46 CVD). TG:HDL sex-specific cutoffs: Salazar 2012 AmJCardiol; von Bibra 2017 HormMetabRes. None of these outputs are clinical diagnoses. Discuss with your provider.
Shift Health Calculator
Evidence Base
All CDI formula weights and clinical thresholds are grounded in peer-reviewed literature. The calculator is an educational tool — not a validated clinical instrument.
🌙Circadian Disruption Index (CDI) FormulaCore Formula▾
The CDI is a weighted composite developed for educational risk-stratification. It draws on published circadian disruption research but has not been independently validated as a predictive clinical test.
Component
Weight
Source
Night shift frequency (nights × 0.6)
0.6 per night
Vyas et al., 2012 — BMJ (23% higher MI risk)
Total night hours (nightHrs ÷ 10)
÷ 10
Cumulative exposure load
Quick returns (× 0.4, cap 3)
0.4 per QR
Tucker et al., 2021 — Sleep Med Rev (acute fatigue risk)
AI-powered responses. This assistant uses Claude (Anthropic). It is not a physician and does not have access to your medical records. All responses are educational information only.
Chat messages are processed by Anthropic's AI — not stored on this site.
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Your questions are sent to Anthropic's API. Do not include personal identifiers in your questions.
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Not a replacement for medical advice. Discuss any findings with your healthcare provider.
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If you are in crisis — call 9-8-8 or 1-833-456-4566 immediately. This AI is not a crisis service.
💬 Ask Shift Health AI
Ask anything about your results or circadian health
Hi! I'm your Shift Health AI assistant. I can explain your Circadian Disruption Index, discuss what your score means for your health, or answer questions about shift worker health and sleep. What's on your mind?
What does my CDI score mean?
How does night shift affect my heart?
Tips to improve sleep after nights
What is circadian disruption?
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Your anonymous score helps researchers and health systems understand population trends. No personal information is ever collected.
✓ Thank you — your contribution helps future health research.
This tool is educational only — not a diagnostic instrument. No name, email, IP address or device ID collected. Score cannot be traced back to you.