Travel Fatigue, Explained
Five schedule stressors, one index, and an effect size smaller than most people claim.
The Standard take
The fatigue index adds five weighted schedule stressors — distance, circadian disruption, lost rest, altitude, and back-to-backs — onto a 0–100 scale and maps that scale linearly onto an expected team-efficiency decrement of up to 5%. It is a good description of how hard a schedule spot was and a poor predictor of who wins a single game, because the effect is real, consistent, and small.
Evidence: emerging, effect direction consistent, magnitude contested · Run it in the Travel Fatigue Calculator.
The formula
Index = min(100, DistanceLoad + CircadianLoad + RestDeficit + Altitude + B2B)
DistanceLoad = miles / 120
CircadianLoad = timeZones × 8 × directionMultiplier
directionMultiplier = 1.4 east · 1.0 west · 0 none
RestDeficit = max(0, 2 − restDays) × 12
Altitude = feetGained / 400
B2B = backToBackGames × 14
ΔPerformance = −(Index / 100) × 5%
- Distance load
- Time in transit, cabin pressure, and disrupted routine, scaled so a 1,200-mile flight contributes 10 points. Distance is a proxy for hours away from a normal day, not for any single physiological mechanism.
- Circadian load
- Eight points per time zone, multiplied by direction. A three-zone eastward trip alone contributes 33.6 points — the single largest term in most road trips.
- Rest deficit
- Penalizes anything below two days at the destination, at 12 points per missing day. Two days is the point at which most of the acute travel load has been slept off.
- Altitude
- Elevation gain versus home, at a quarter point per 100 feet. A sea-level team arriving at 5,200 feet picks up 13 points.
- Back-to-backs
- Fourteen points per consecutive game with under 24 hours of turnaround — the best-evidenced of the five inputs, and the only one a league can fix with a pen.
The assumptions
- The stressors are additive. The model adds each term as if it never interacts with the others. In reality a long eastward flight and a back-to-back compound one another.
- The mapping to performance is linear. Index 100 means a 5% decrement, index 50 means 2.5%. There is no evidence the real dose response is a straight line; it is a simplification chosen for legibility.
- Weights are judgment calls. They are set so realistic road trips land in sensible bands, informed by circadian and schedule density literature. They are not regression coefficients fitted to a game database.
- Every roster responds identically. No term describes age, sleep habits, charter quality, or acclimatization.
- Home is the baseline. A rested home team is defined as zero. Teams that live at altitude are not credited for it here.
A worked example
A West Coast team flies 1,800 miles east across three time zones, arrives with one day of rest, at 600 feet of elevation gain, and plays the second of a back-to-back.
| Component | Math | Points |
|---|---|---|
| Distance | 1,800 / 120 | 15.0 |
| Circadian | 3 × 8 × 1.4 | 33.6 |
| Rest deficit | (2 − 1) × 12 | 12.0 |
| Altitude | 600 / 400 | 1.5 |
| Back-to-back | 1 × 14 | 14.0 |
| Index | sum, rounded | 76 |
| Δ Performance | −(76 / 100) × 5 | −3.8% |
Seventy-six is a severe spot. Now fly the same trip westward and the circadian term drops to 24 — the index falls to 66 and the expected decrement to 3.3%. Same miles, same rest, one direction of travel.
Where it breaks
- Single games. A 3% expected decrement is far smaller than the game-to-game variance of any team. The index cannot call a result.
- Sports with long turnarounds. A football week absorbs almost all of this. The model is most useful in dense basketball and baseball schedules.
- Acclimatized teams. Clubs that live at altitude or fly constantly adapt, and nothing in the inputs captures adaptation.
- Double counting. Distance and time zones are correlated, so long east–west trips are penalized twice by design.
- Rotation. A coach resting starters in a bad spot produces the same box score as fatigue, and the model cannot tell them apart.
FAQ
What is a fatigue index?
A single 0–100 score that adds up the schedule stressors a team absorbed before a game: distance flown, time zones crossed, rest days lost, altitude gained, and games played back-to-back. It is a bookkeeping device for schedule difficulty, not a medical measurement of any individual athlete.
Why is eastward travel scored harder than westward?
The human body clock runs slightly longer than 24 hours, so delaying it (flying west) is easier than advancing it (flying east). Our model applies a 1.4× multiplier to eastward time-zone crossings and no circadian penalty when no zones are crossed.
How big is the real effect on results?
Small. Published work on jet lag and schedule density generally finds effects in the low single digits of percentage points on team efficiency, and it is easily swamped by roster quality. Our model caps the expected decrement at 5%.
Does the index apply to one player or the whole team?
The whole team. Individual responses to travel and sleep loss vary enormously, and nothing in the inputs describes an individual body.
Why does altitude count separately from distance?
Reduced oxygen availability is a physiological stressor independent of how far you flew. A short flight into a mile-high venue carries a load that the mileage term would miss entirely.
Can I use this to bet a game?
No. The effect size is small, markets price schedule spots already, and the model omits injuries, motivation, and roster rotation. Use it to explain a performance after the fact, or to plan a recovery schedule.