Sleep Researchers To Study Glenn During Historic Flight

By William J. Cromie

Gazette Staff

Astronauts and elderly people have a lot in common, according to astroSenator John Glenn. For one thing, both of them have trouble sleeping, albeit for different reasons.

"It is one of some 50 physiological changes experienced by both older people and astronauts on long spaceflights," Glenn said. "Other changes include thinning bones, weakened muscles, impaired balance, and alterations in function of the heart, blood flow, and immune system. If, through experiments in space, we can determine what regulates these systems, that would be a giant step toward helping the old and frail on Earth."

In 1996, Glenn suggested to Daniel Goldin, head of the National Aeronautics and Space Administration (NASA), that someone should look into this. He had himself in mind.

Today, he is scheduled to climb aboard the space shuttle Discovery and spend nine days orbiting Earth with six other astronauts. During this time, Glenn, 77, will wear instruments on his head, wrist, and chest and will swallow radio-equipped pills that continuously measure his body temperature.

A female colleague, Chiaki Mukai, 46, will test melatonin, a popular, over-the-counter substance that many people take as a sleeping pill. Darkness stimulates the brain to secrete this hormone naturally, and Richard Wurtman, a scientist at the Massachusetts Institute of Technology, calls it "the hormone of darkness."

"Despite its wide use to bring on sleep, reduce jet lag, and adapt to night shifts, no large medical trials have been done to determine if it is a safe and effective treatment for insomnia," notes Charles Czeisler, professor of medicine at the Medical School, who is in charge of the sleep experiments. He points out that tests on animals show "melatonin can shut down the reproductive system. The testes of hamsters given the hormone shrunk to one-tenth of normal size. That's not mentioned in advertisements for the drug."

Health stores sell melatonin in 3-, 5-, and 10-milligram tablets, which can raise blood levels of melatonin hundreds of times higher than normal. You can even buy brands labeled "melatonin," which may not contain any of the hormone. No Food and Drug Administration testing is required to assure either potency or safety.

Czeisler, who is director of circadian and sleep disorders medicine at Harvard-affiliated Brigham and Women's Hospital in Boston, has been investigating melatonin as part of research on how and why sleep disruptions increase with age. Glenn points out that "half of people older than 65 have trouble sleeping, and disordered sleep impairs the health of one-third of all elders." He says he is not one of them. Such people wake up before they want to, have trouble staying awake in the evenings, and suffer from shallow, fragmented sleep.

In the hope that melatonin may effectively treat such problems, Czeisler and colleagues James Wyatt and Derk-Jan Dijk have given 36 subjects different doses of the hormone in experiments. Based on an analysis of the results, they conclude that 0.3 milligrams puts a person to sleep and avoids the troublesome effects of other types of sleeping pills, such as reduced reaction time, lessened alertness, and impaired memory.

"This dose is close to the amount of melatonin produced naturally by the pineal gland in the brain," Czeisler notes.

Flights to Insomnia

Sleeping in a spacecraft is not easy. Space shuttles orbit Earth in 90 minutes, so the sun rises or sets every 45 minutes. Sleeping quarters are small and noisy. Astronauts don't lie down in warm comfortable beds. They sleep vertically in sacks fastened to walls so they won't float weightlessly due to an almost complete absence of gravity. To make matters worse, they go to bed 45 minutes earlier each day to ready them for their landing schedule.

"This continual shift in bedtime almost guarantees insomnia," Czeisler comments. "Over the course of a nine-day mission, it results in the same kind of jet lag you experience when flying from Boston to London or Paris."

To counter such effects, about 20 percent of astronauts take sleeping pills (benzodiazepines) on single-shift missions; on double-shift trips, half of them rely on the drugs. "They take pills at a rate three-to-eight times greater than people on the ground, despite the fact that they are in excellent health," Czeisler remarks.

Concerned that this could impair their performance, NASA, in 1993, decided to try melatonin. However, Czeisler warned them that the drug had not been proved safe or effective. The result was the first scientific test of a drug in space.

During a 16-day mission aboard the shuttle Columbia last April, four astronauts took either melatonin or a pill that contained no medication, a placebo. Neither astronauts nor scientists doing the study knew who got which on which nights. At "night," astronauts wore instrumented caps that recorded how well they slept. By correlating brain wave and other measurements with their levels of performance, Czeisler's team expects to determine the effectiveness of melatonin for aiding a good night's sleep and a good day's work.

Collaborating with John West and his team at the University of California, San Diego, Czeisler, Derk-Jan Dijk, and colleague Joseph Ronda are still analyzing data from the April flight. They do not yet have enough information to give the drug a passing grade.

Swallowing Radios

Glenn will not take melatonin, but his sleep, and that of Chiaki Mukai, will be monitored by night, and their alertness measured by day. During four of the nine nights, the senator and Mukai will wear instrumented caps that record their brain waves and eye movements. This setup allows researchers on the ground to determine the quality of sleep of one astronaut who takes melatonin and one who does not.

The two also must wear a tight vest fitted with instruments to monitor breathing. West and Czeisler think that changes in respiration due to weightlessness can disturb sleep in space. The garment is known as a Respiratory Inductance Plethysmograph vest. Glenn noted with a grin that it's called an R.I.P. suit for short.

On other nights, Glenn and Mukai will wear electronic sensors on their wrists to keep track of body movements. Such movements indicate if they are sleeping or not, and how well. After testing these instruments on the ground, Glenn insists they do not interfere with his sleep.

Each day, the senator and Mukai will be tested for alertness, reaction time, and job performance. One test involves solving math problems. The results of such tests can be compared with how well they slept on previous nights.

According to Rod Hughes and Joseph Ronda, who manage the experiment, Glenn and Mukai will swallow pills -- about the size of a large vitamin tablet -- that contain both a thermometer and a radio. The radio broadcasts body-temperature readings to a small, wearable receiver until it is passed from the astronaut's body. Then another pill must be swallowed.

Body temperatures reveal what time it is according to a person's natural, or biological, clock. The power source of this clock is an area deep in the brain that regulates body temperature, natural melatonin levels, sleep and wakefulness. When biological and clock times get out of synchronization, people have difficulty sleeping, staying awake, or both. Jet lag is a good example.

Public Relations Stunt?

Whenever Glenn discusses the flight with reporters, someone asks whether his sleeping and other medical experiments are merely a public relations stunt designed by NASA to revive flagging interest in the space program. Glenn was the first American to orbit Earth, circling the planet three times on Feb. 20, 1962. Two other Americans preceded him into space (Alan Shepard and Virgil "Gus" Grissom), and two Soviet cosmonauts orbited Earth months before Glenn (Yuri Gagarin in April 1961 and Gherman Titov in August 1961). Titov spent 25 hours in space, Glenn spent five hours. Nevertheless, Glenn became the nation's number one space hero. NASA grounded him to make speeches and appearances and to avoid any possibility of his being killed on a subsequent mission.

"I've always wanted to go back into space; I won't deny that," he said in a July interview. "But I also believe there are solid scientific reasons for going."

NASA reviewed Glenn's request for a year before deciding he could fly -- if he fulfilled two conditions. He had to pass the same physical examination as other astronauts, and medical experiments on a 77-year-old had to stand on their own scientific merit. Evidently, both requirements were satisfied, and NASA will get a terrific public relations bonus.

Glenn admitted that Annie, his wife of 55 years, "was a little cool to the idea at first. But now she's OK with it." His son and daughter and two grandchildren, Glenn says, "also are enthusiastic about the flight.

"I'm looking forward to it," Glenn commented with his famous engaging smile. "I'm thrilled to go up again, and I'm proud to be part of an experiment that could benefit so many people on Earth."

-- William Cromie covered Glenn's 1962 flight as a reporter for World Book Encyclopedia's newspaper service.