Presidents are never really on vacation, as George W. Bush discovered to his great cost, about four years ago.

As his critics are fond of pointing out, Bush the younger was on vacation down on the ranch when Hurricane Katrina devastated New Orleans. And he stayed on vacation for three days afterwards. Now, when people enumerate the many failings of his Presidency, the first three nominated are usually the economic crisis, the Iraq war and the failure to respond to Katrina.

Mr. Bush was also on vacation when he was supposed to be reading the intelligence which warned of a potential Al Qaeda attack on America, four years before that. August can be the cruelest month for Presidents. With Congress not in session, and the pace of national life slowed by the summer, said Stephen Hess, a presidential historian at the Brookings Institute: “August is a month where they expect nothing to happen, yet it turns out historically a lot can happen. The classic example was George W. Bush, who didn’t respond properly to Katrina. He flew over on the way back to Washington. People notice those things.”

Yet who would deny the President a little rest and recreation? He has the most demanding job in the world.

“People who seek the presidency want the pressure; they are not like the rest of us,” said Mr. Hess. “Even so, it is really quite beyond what they expected, even as a candidate.

“They need some time to rest and recreate.”

And most of them realize this. Richard Nixon was a rare exception; he believed a President should take no time off at all. And we all know how he ended up — sliding into paranoid and ultimately criminal behavior.

John F. Kennedy and Franklin Roosevelt sailed. The elder George Bush retreated to his place in Kennebunkport, Me., and also messed around in boats. Jimmy Carter went fly-fishing. Bill Clinton hung out here on the Vineyard. (It’s interesting how they all seem drawn to the soothing rhythms of water.)

But, as we said at the top, they are never really off duty. Problems arise. In some cases, the vacations themselves can pose political problems.

“With Bill Clinton,” said Mr. Hess, “it looked as if he were doing too much hanging out with rich people and celebrities. Dick Morris, an advisor at the time said, ‘For heaven’s sake, go out and have a vacation in a national park.’ So he did, and of course had a miserable time and never did that again.

“There is always an eye on public relations. In some situations, depending on the degree to which an administration wants to look busy, the press office can sort of scurry up people to give reports and that sort of thing.”

Not that Mr. Hess expects any of that sort of criticism or reflexive activity from the upcoming Obama holiday at Blue Heron Farm — he’s just become President, he’s been very obviously very busy and is clearly planning a low-key, family-centered retreat.

And, make no mistake, he will still be working much of the time.

In America, in contrast to many other countries, no presidential responsibilities ever devolve to anyone else. (During the 977 days George W. Bush took off from the White House — time split roughly equally between Camp David and his Crawford, Tex., ranch — Dick Cheney was never in charge, despite appearances.) This is quite unlike many of the Parliamentary democracies, where the Prime Minister’s deputy assumes the role of acting Prime Minister now and then, so the leader can get a break.

“While the staff work to give a President as much space as possible, he still has to stay in touch and not lose sight of anything,” Mr. Hess said.

“They have to protect themselves, making sure nothing is happening around the world that you need take action on. That means the national security advisors briefing him every morning. And he’s got to know something of the progress of the domestic agenda that he cares about.”

Presidents have different ways of relaxing. George Washington surveyed potential sites for a national capital. George H.W. Bush maintained a grueling schedule of speed golf and running. His son rode mountain bikes and cut brush. Bill Clinton networked. Jimmy Carter conspicuously did not network. And some are better than others at de-stressing. Franklin Roosevelt said he never had any trouble falling immediately asleep at night, but medical evidence (given at a recent seminar on the importance of vacations) showed his pulse rate and blood pressure climbed through his presidency, leading eventually to his fatal stroke.

And Barack Obama? He has so far shown himself to be “pretty good at having a good time” said Mr. Hess. “He actually goes out with his wife from time to time. He takes his children places.”

Joe Robinson, who runs the company Work to Live and who lectures corporate and government clients on work-life balance issues, agrees.

“One of the most interesting things Barack Obama did during the campaign was take a vacation for a week, right in the middle of it. People said he couldn’t, the other side would have all kinds of opportunities. But he insisted on it,” he said.

“I admired that.” Apart from the benefit to the President and his family of insisting on some downtime, they served as important role models for the country.

“He shows the rest of us that as busy as he is, he is going to take time because it is important,” said Mr. Robinson, reeling off statistics showing the benefits of vacations.

“We know that about one-third less families are taking vacations with their kids than in the 1970s. We have to get our kids into these experiences at a young age, or lose them to technology, watching screens, being spectators.

“Research shows an annual vacation cuts the risk of heart attack by a third in men, and when you take more than one a year, cuts the risk by 50 per cent. A vacation is as important as watching your cholesterol or getting exercise,” he said.

“And the brain goes down way before the body.”

Yet the average American now takes just three or four days off each year. One in seven will take no vacation at all this year.

“We really have it backwards in this country. We believe the burnout model is the way to go. But it’s actually the opposite. In a knowledge economy, it’s really all about how fresh your brain is.

“Play breaks up the mental set. The group of associations in your mind causing stress is blown away. It sparks imagination, inspiration and creativity. Productivity increases when you come back from vacation, in some measured cases as much as 80 per cent,” he said.

A number of European countries, where people average six weeks paid leave each year, show significantly higher worker productivity.

It is hard to measure presidential productivity, but there is anecdotal evidence they, too, benefit from a little head-clearing time. Reportedly, for example, FDR got the idea for the lend-lease scheme which saved Britain from bankruptcy in World War II while he was on vacation.

So it seems we should not begrudge the Obamas their downtime at Blue Heron Farm, for what is good for the President is good for the nation. Rather, let us endorse the President in his idle moments, as a role model to us all.