Shift Pattern Health Analyser
Pick a UK shift pattern and see its fatigue-risk profile: circadian disruption, cumulative load, recovery adequacy, and the worst days of the cycle. Compare two rotas side-by-side.
4-on-4-off
Elevated risk4-on-4-off is an elevated-risk pattern. Most workers tolerate it for years with deliberate habits; without them the cumulative toll is measurable.
Recommendations
- Highest-risk day in the cycle: day 4 (day shift). Treat this day as no-social-commitment, eat properly pre-shift, and guard the post-shift wind-down.
- Twelve-hour shifts concentrate fatigue in the final 3 hours. Reserve decision-heavy or safety-critical tasks for hours 1–9 where possible.
- Rotating patterns benefit most from consistent meal times and an 'anchor sleep' block across shift types — a 3–4 hour window that stays the same whether you're on days or nights.
- Long recovery blocks (4 consecutive off days) are this pattern's strongest protective feature — treat day 1 as rest, days 2–3 as training, day 4 as wind-down for the next shift block.
How this scoring works
Scores combine five signals from the programmatic shift-pattern dataset: baseline fatigue by segment (night > early > late > day), cumulative load from consecutive same-shift blocks, a penalty for transition days between segments, a shift-length adjustment (8h vs 10h vs 12h), a rotation-direction multiplier (forward-rotating earlies → lates → nights is easier on the body clock than backward-rotating), and a recovery deduction per consecutive off day.
This is an evidence-informed simplification of the HSE Fatigue Risk Index — not a direct clone. The HSE FRI uses proprietary calibration; this tool is transparent, fully client-side, and uses only the public literature. Use it as a framing lens, not a medical judgement. For clinical decisions about workforce scheduling, consult occupational-health professionals and the HSE shift-work guidance.