Pick the most consequential meeting of your last quarter. The odds are good that you flew to it, and reasonable that you landed the same morning.
The founder's load profile has a feature almost no other deciding profession shares: the constant collision of long-haul travel with high-stakes judgement. Surgeons don't operate across eight time zones. Judges don't hear cases the morning they land from the other hemisphere. But the founder's calendar routinely stacks the two: the flight and the decision, back to back, as if the only cost of travel were the hours it consumes.
The actual cost is physiological, and it's not tiredness. Tiredness is what you feel; circadian disruption is what happens. Crossing time zones doesn't just shortchange your sleep. It desynchronises the clocks that run you. Every major system in the body keeps time: cortisol rhythm, core temperature, digestion, the timing of alertness and the timing of repair. Cross enough zones and these clocks stop agreeing with each other and with the sun outside, and the reconciliation takes days. The standard rule of thumb puts realignment at roughly a day per zone crossed, with eastward travel harder than westward. During the reconciliation, the capacities this whole series is about (sustained attention, working memory, impulse control, the reliability of the gut signal) are measurably off their baseline, in ways the person experiencing them systematically underestimates. That last clause is the dangerous one. The research on sleep restriction and circadian misalignment keeps finding the same cruel design: performance degrades faster than the perception of performance, so the depleted traveller feels merely a bit flat while testing considerably worse. You land, you feel fine, honestly, and you are the least qualified observer in the airport on the question.
Aviation understood all of this decades ago, and its response produced one of the great unexamined ironies of your working life. Pilot duty time is regulated by law, with hard limits on hours, mandated rest, and rules built specifically around fatigue and circadian science, because a degraded human making consequential decisions was deemed an unacceptable systemic risk. Now watch the plane land. The pilot, whose state was protected by statute, is done for the day. The passenger in 2A, who slept four broken hours, whose clocks are scattered across two continents, and whose decision this afternoon is worth more than the aircraft, walks straight off the jet bridge into a term sheet negotiation. Every safeguard on that flight existed for the person whose judgement mattered least by dollar value. Nobody regulates the passenger. The passenger doesn't even regulate themself.
And the schedule actively encourages the collision, because of how calendars price travel. A flight costs hours, and hours appear in the diary, so hours get managed. The circadian debt costs capacity, and capacity appears nowhere, so it gets spent freely. This is the entire logic of the red-eye: it "saves a day." Look at the transaction honestly. The overnight flight converts a day of calendar time into several days of degraded state. It doesn't save the day, it borrows it, from precisely the account this series has been arguing is your scarcest: the quality of what you decide on arrival. The loan is invisible, the interest is compounding, and the repayment gets booked, if anything goes wrong, as a tough negotiation or a bad market.
The response, as ever in this series, is not the obvious one. You cannot travel less; the suggestion is the same category error as "do fewer decisions," and anyone offering it doesn't understand the job. The response is to price travel correctly: to treat zones crossed as a real cost, with a known repayment schedule, and place decisions accordingly. In practice that means the things sport figured out when its assets started flying to fixtures: arrival buffers sized to the zones crossed, not to the meeting's convenience; the consequential call scheduled for the day your measured recovery says you've reconciled, not the day you land; the red-eye reserved for trips where nothing on the other end requires your judgement at full capacity; and, the piece none of the generic advice can supply, your own recovery signature, mapped, because the day-per-zone rule is a population average and you are, as an earlier essay argued, a study of one. Some systems reconcile in half the textbook time; some take double. Not knowing which you are means every itinerary is a guess about the one variable that matters.
None of this appears on any expense report, which is exactly the problem. The flight was £4,000 and got approved. The three days of discounted judgement that followed it were free, invisible, and worth more than the company's annual travel budget.
The red-eye never saved you a day. It moved the cost somewhere you don't audit.