Since heading off on our travels at the start of the week, I really can’t emphasise enough how having learned a little about sleep in Week 1 has been paying regular dividends: now I understand that resting when tired (rather than when you’re supposed to), dozing (where previously I just would have gotten up) and regular napping are allowed, I’m really putting a dent in my sleep debt, even when faced with obstacles like jet lag and extensive train travel.

I’m writing this at 5am in the morning on a train crossing Washington State, having crossed several time zones and only managed naps and small bouts of sleep over the last 40-odd hours, yet I feel rested and refreshed. This is massive progress. So hear me now – if you ever struggle with sleep, I’d heartily recommend attempting a small amount of research and remedial action: sometimes a little work outside your comfort zone can have a big payoff.