Now, halfway between Cape Horn and the Equator, with at least 5,000 miles left, her advantage over the record has slipped from five days last week to less than three yesterday.

Sleep represents something of a Catch-22; she knows that she must sleep in order to achieve the mental and physical condition to keep making good time but that each time she does, she is losing time.

According to her support team, the demands of the record mean that she is under greater strain than at any time in her career. If she is not careful, she will reach the stage of hallucination.

MacArthur wears a monitoring device on an arm and the data from it is sent to Boston to be analysed by Claudio Stampi, the chronobiologist with whom she has worked for the past five years.

From the start, on November 30, until January 12, she averaged 5.54 hours sleep a day. But from January 6 to the 12th, MacArthur averaged just 3.9 hours. “Under normal circumstances this would already represent quite a sacrificed sleep allowance in comparison to the two-week transatlantic race in 2000, where Ellen averaged 4.2 hours per day,” Stampi said. “But this low sleep quota will have an even more dramatic impact on someone who is particularly fatigued having been at sea for 50 days.”

MacArthur’s sleep patterns are usually feverish, mostly divided into ten or 20 minutes, but napping is one of her strategies. According to Stampi, for the 94 days of the Vendée Globe in 2000-01, MacArthur averaged 5.7 hours sleep a day, divided into nine naps.

“When you have to go from an average of 7½ hours a day to Ellen’s average of 5½,” Stampi said, “we have seen from many experiments that it is actually better to divide those fewer hours into multiple naps.”

Last week, though, things deteriorated. The worst recorded day was January 6, when she had 1.5 hours of sleep. “But the worst two days have come since that data when she went round Cape Horn,” Mark Turner, MacArthur’s manager, said. “The problem is you have that adrenalin from the Southern Ocean and the Cape Horn, but the reality is it doesn’t become easier.

“I think she’s stepped back from the brink, slightly. She definitely was right on the edge (last Saturday). She managed to get five hours’ sleep on Sunday but it’s not a question of one good night’s sleep.” Except that one day can make a big difference.

Another of Stampi’s suggestions is the “Sunday Strategy; that is the strategy of once a week, declaring a different day — like a vacation day, or half-day”, Stampi said. “That is both psychologically as well as from a sleep perspective. Sleep seems to be extremely plastic. One day is enough to put you back to a very good level.

“Ellen, from a sleep physiology perspective, is a normal person. Where she is exceptional is in her drive and discipline. You will never find a day without sleep with Ellen. Not every sailor can do that. Some will stay a day, two, sometimes three, without sleep at all. The benefits of even a short nap are disproportionate to the duration.”

But Stampi has been worried, thatis for sure. “Hallucination is a sign of very, very severe sleep deprivation,” he said. “She was close to that.”

MacArthur’s message yesterday spoke of the pressure. “The six hours before sunrise were the lowest of the lows, ever in my life, I think.

“I have to try and rest now, I have not slept for five minutes even for days, it feels like.” Then her headsail gave way temporarily and it was time for more DIY.

LINKS

Follow Ellen MacArthur's progress at www.teamellen.com

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