Astronauts explore the role of dreaming in space
By William J. Cromie
Astronauts and cosmonauts have been reporting strange dreams.
One cosmonaut notes that, when in space, he never dreams of being on Earth; he's always floating weightlessly in space. Another comments that his dreams, when aloft, are much more intense than on the ground.
The sensation of falling kept one U.S. astronaut from getting to sleep. He solved the problem by picturing himself as a spacecraft orbiting Earth. That image calmed him enough so that he could fall asleep.
A group of researchers at the Medical School believes such dreamy experiences reflect the adaptation of Earthlings to spaceflight. Rapid eye movements (REM) signal that a sleeper is dreaming, so they are investigating such eye shifting before, during, and after spaceflights
"We think REM sleep promotes changes in the brain that help astronauts adapt their motor system, particularly balance, to the near absence of gravity," says J. Allan Hobson, professor of psychiatry. "There is evidence of a feedback mechanism wherein adaptation to weightlessness increases REM sleep and dreaming, which in turn may enhance balance, orientation, and movement."
Such adjustment bears on the problem of motion sickness, which plagues most astronauts, sometimes for the entire length of their spaceflights. The National Aeronautics and Space Administration (NASA) and the astronauts seldom mention the toll that space sickness takes. Nausea and malaise do not fit their image of "the right stuff."
To look into the motion commotion, Hobson and his colleagues at the Laboratory of Neurophysiology have fitted astronauts and cosmonauts with special "Nightcaps" to record their dreams while they live aboard the Russian space station Mir. The slumbernauts include Jerry Linenger, 41, a medical doctor, who boarded Mir on Jan. 11. "Mir" means "peace."
If all goes as planned, Linenger will be joined next week by Nightcap cosmonauts Vasilii Tsibliev, who will take over command of Mir, and flight engineer Aleksandr Lazutkin.
Robert Stickgold, assistant professor of psychiatry, recorded the REM sleep and dreams of all three in preflight sessions in Russia and Houston, Texas. These records of sleep, dreams, and head movements will be compared with those during and after months of space flight.
"No one has tracked the sleep and dreams of people in space for more than a few days," Stickgold points out. "Knowing how they change over prolonged periods is essential for extended missions aboard space stations, to Mars and, perhaps, to colonies on the Moon."
"We need to understand how REM sleep and the vestibular system that controls balance and body position work together to help the body to learn about and adjust to new spatial situations." Hobson adds. "For example, infants spend a great deal of time in REM sleep; that may be a way to get their motor system prepared for standing, walking, and running."
Many researchers believe the purpose of sleep is to promote memory and consolidation of what is learned during the day. Dreams may involve memories of vestibular learning; they are filled with continual movement -- running, flying, spinning, twitching, and turning.
Wearing a Nightcap
Another goal of the dreamy experiment is to give the Nightcap its most challenging test to date. Researchers at the Laboratory of Neurophysiology invented it as a simple, inexpensive substitute for the large, polygraph-like dream-recording machines, which cost $10,000 or more and require dreamers to be hooked up to a tangle of electrodes and wires in a sleep lab.
A band worn around the head holds sensors that detect eyelid and head movements. Head movements distinguish sleep from wakefulness. When people dream, their eyes move rapidly back and forth as though they are watching a movie in the little theater of the mind. A sensor placed on the left eyelid picks up such rapid eye movements.
The sensor connects to a recorder as small as a pocket-sized tape player. For actual dream content, researchers must rely on sleepers' memories. Ordinarily, that information is notoriously difficult to recall. However, Hobson and Stickgold find, from personal experience, that a few nights of training can save dreams from oblivion.
"When you start to pay attention to your dreams, you start to recall them," Stickgold comments. "When we tried it ourselves, recall wasn't too good at first. But by the fourth or fifth night, we were flooded with memories of our dreams. We hope the same happens in space."
Dream On, Astronaut
If Hobson is right, astronauts and cosmonauts will dream much more than they do on Earth simply because there's more motion for them to cope with. Weightlessness takes away up and down as references.
Take sleeping, for instance. Astronauts can't lie down to sleep. They can't put their head on a pillow unless they tie it to their cheek.
They often sleep in a bag tied inside a compartment the size of a telephone booth. On early flights, astronauts worried that lack of air movement would cause them to suffocate on the carbon dioxide in their own exhalations. (In the 1950s, medical experts feared that spacemen would choke on food they wouldn't be able to swallow.)
NASA put fans in the sleeping compartments, but they blew too much air up an astronaut's nose, preventing sleep. If the spacemen tried to sleep head down, the sleeping bags blew up like balloons.
Some astronauts now bungee themselves to a wall, or just float free in the cargo area. "Free floaters may gently bump against walls, but they push off just like an Earth sleeper turns over," Stickgold explains.
Spaceflight also takes away the 24-hour cycle of night and day. Mir orbits Earth every 90 minutes, creating a confusion of sunrises and sunsets every 45 minutes.
Such changes savage orientation, balance, sleep, and dreams. Sleep and dreams are controlled by nerves in the lower part of the brain, just above the spinal cord. These nerves are intimately connected with those involved in balance. The latter go to the eyes, which inform the brain of changes in head position.
When awake, the brain coordinates movements of the head and muscles to maintain a stable body position. During sleep, other nerve systems temporarily paralyze muscles to prevent what could be dangerous acting-out of dreams.
"When we dream, we are functionally quadraplegic," Stickgold notes. "We let the clutch out," Hobson adds. Our mental wheels spin but they do not connect to our motion engine.
Too much of a chemical called acetylcholine in the nervous system is thought to promote motion sickness. The same chemical brings on dreams. Drugs given to astronauts to block motion sickness, therefore, could retard dreaming. If Hobson is right, blocking dreaming might interfere with an astronaut's adjustment to the confusing, sickening movements they feel in space.
Then there's the problem of readaptation to gravity. A confused vestibular system, added to problems of bone-calcium loss, weakened muscles, and heart deconditioning, has NASA worried about the physical effects of long spaceflights. Astronaut John Blaha, in a gesture considered the antithesis of the "right stuff," agreed to be carried off his spacecraft after four months aboard Mir so doctors could accurately measure such deterioration.
Astronauts who float in space for a week or more need visual cues to find their way around after they first land. Stickgold tells about a spaceman, recently returned to gravity, who got into bed one night without turning off the light. He feared getting up to turn it out because he wasn't sure he could walk in the dark. Even crawling might not work; insecurity about knowing up from down could cause him to flop over on his side. He had to call someone from his bedside telephone to come over and turn off the light.
Stickgold, Hobson, and their colleagues will record the postflight sleep and dreams of returning slumbernauts to try to understand what role they play in readaptation to gravity and 24-hour days.
Meanwhile, the Harvard researchers have begun recording the preflight sleep and dreams of the next U.S. and Russian crew members who will fly on Mir. The effort should eventually produce sounder sleep, sweeter dreams, and better balance for all astronauts and cosmonauts.
Copyright 1998 President and Fellows of Harvard College