About the authors
Dan Caldwell is distinguished professor of political science at Pepperdine University and the author of "Vortex of Conflict: U.S. Policy toward Afghanistan, Pakistan, and Iraq."
William G. Hocking is a practicing physician, the former president of the Marshfield Clinic and the co-author of several recent articles in The New England Journal of Medicine.

U.S. Secretary of State John Kerry walks past an honor guard as he disembarks from his airplane upon arrival at Seoul Air Base in South Korea. (Saul Loeb/Reuters)

Jet lag is a pain for weary travelers. But for diplomats, it can be a killer.

The most famous case of jet lag-addled negotiations occurred in 1956, when Secretary of State John Foster Dulles flew to Egypt and agreed to provide U.S. economic aid to build the Aswan Dam. After a long return flight to Washington, Dulles learned that the Egyptians had bought a significant number of Soviet weapons. Furious, he immediately canceled the Aswan agreement he had made with Egyptian leader Nasser, which opened the way for the Soviet Union to fund the project and improve its relations with Egypt and its position in the Middle East.

Years later, Dulles indicated that he thought that the cancellation of the agreement was a significant mistake and that it was due to the effects of jet lag.

Anyone who has flown across multiple time zones has experienced some of the symptoms of jet lag — fatigue, loss of appetite, headaches, irritability and impairment of both cognitive and physical performance. These symptoms may be bothersome or inconvenient for tourists. But they can crucially impair high-level leaders and diplomats who engage in significant negotiations and discussions.

Jet lag has affected world leaders many times and in embarrassing ways. In 1992,  President George H.W. Bush was in Japan on the 10th of a 12-day, 26,000-mile tour of four Asian countries. At a state dinner in his honor, the president suddenly fell ill, vomited on himself and his host — Japanese Prime Minister Miyazawa. The president’s spokesperson, Marlin Fitzwater, later explained that Bush had suffered an attack of gastroenteritis. Given Bush’s extensive itinerary, it is quite possible that his condition was brought on by jet lag.

Henry Kissinger traveled a great deal both as President Richard M. Nixon’s national security assistant and as secretary of state. He was also very cognizant of the effects and dangers of jet lag. In recalling his negotiations with North Vietnamese diplomat Le Duc Tho, Kissinger noted: “[w]hen I went directly from a transatlantic flight into talks, I found I was on the verge of losing my temper at North Vietnamese insolence — nearly falling into their trap by playing the role they had assigned to me. From then on I never began a negotiation immediately after a long flight.”

Kissinger applied this rule to dealing with his Soviet interlocutors: “I had told [Soviet Ambassador] Dobrynin that I never negotiated immediately after a long flight across many time zones and would not be prepared to begin talks until Sunday morning Moscow time, more than thirty-six hours away.”

During her four years as secretary of state, Hillary Clinton traveled almost a million air miles and visited 112 of the world’s 200 countries. She was on the road 401 days and spent the equivalent of 87 full days on a plane. On a single trip lasting 12 days in the summer of 2012, Clinton flew to France, Afghanistan, Japan, Mongolia, Vietnam, Laos, Cambodia, Egypt and Israel. Staff members of the National Security Council and the State Department told us in interviews that Obama was so concerned about her grueling travel schedule that he ordered her to cut back.

According to  Clinton’s former speechwriter, Lissa Muscatine: “On these trips, you’re in different time zones, your body clock is way off schedule, you’re not routinely getting exercise, and you’re not eating healthy food. On top of that, she has to be operating at the height of mental acuity at all times.” In December 2012, Clinton suffered from gastroenteritis, became weakened, fell and suffered a concussion. While many factors may have contributed, jet lag is known to impair both physical and mental performance, and it is reasonable to speculate that it played a role in this chain of events.

Jet lag is not unique to American leaders and diplomats. At his opening speech at the June 1973 U.S.-Soviet summit meeting in Washington, D.C., Soviet Communist Party General Secretary Leonid Brezhnev noted that he was wearing two watches — one set on Moscow time and the other on Washington time. The Soviet leader noted that the two watches enabled him to keep track of his body rhythms, but he went on to indicate that he was not sure whether he was seven hours ahead or behind his normal time. Brezhnev’s disjointed comments two nights later at Camp David suggested that he was still affected by jet lag.

Several strategies have been developed to reduce the severity of jet lag and to treat jet lag when it occurs. Since jet lag results from a desynchronized circadian clock, efforts to re-synchronize are important. An important way of dealing with jet lag involves controlled exposure to sunlight.

Almost as part of their national character, Americans tend to believe in pharmaceutical solutions to medical problems, and managing jet lag is no exception. Melatonin is a hormone produced by the pineal gland during darkness, under control of the circadian clock. Melatonin has the effect of synchronizing the circadian system, and studies have shown that melatonin administration may be beneficial in jet lag by helping resynchronize circadian rhythms.

A controversial, although widely used approach to dealing with jet lag is the use of sleeping pills. These agents may help relieve the insomnia that is common with jet lag. However, it is important to avoid agents with long duration of action or side effects such as amnesia, cognitive impairment or a hangover. Despite these possible side-effects, George H. W. Bush, Madeleine Albright  and John Kerry have all admitted taking sleeping pills to try and cope with jet lag.

Current empirical evidence supports the use of moderation in consumption of alcoholic and caffeinated beverages, exposure to sunlight as soon as possible after arrival and at appropriate times following arrival and making an effort to obtain needed rest to obviate the effects of jet lag. The selective use of pharmacological agents including melatonin may be of benefit but should be considered judiciously.

The obvious alternative to jet-setting leaders going from country to country, capital to capital, is a return to dependence on resident diplomats. By minimizing international travel, states could return to traditional diplomacy, relying on their ambassadors to represent their interests and positions to foreign governments. Such an approach might also reduce the stress, fatigue and other negative effects of travel experienced by principal decision-makers.

This article is based on “Jet Lag: A Neglected Problem of Modern Diplomacy,” published recently in “The Hague Journal of Diplomacy.”