Astronauts and sleep deprivation

A recent study found that astronauts suffer from chronic sleep deprivation and many compensate with sleeping pills.

The researchers at the Brigham and Women's Hospital (BWH) Division of Sleep and Circadian Disorders, Harvard Medical School and colleagues found that astronauts get around six hours of sleep during training and space flights. Also, several astronauts use sleeping pills, which could affect their performance during an emergency situation.

The study was conducted over a ten-year period and included data from 64 astronauts on 80 Shuttle missions and 21 astronauts on International Space Station (ISS) missions. This is the largest study of its kind, researchers say.

Sleeping in the shuttle or ISS is difficult because the Sun rises every 90 minutes. The several sunrises and sunsets coupled with excitement of being in space and living in closed quarters can severely affect sleep schedules.

"Sleep deficiency is pervasive among crew members," stated Laura K. Barger, PhD, associate physiologist in the BWH Division of Sleep and Circadian Disorders and lead author of the study, according to a news release. "It's clear that more effective measures are needed to promote adequate sleep in crew members, both during training and space flight, as sleep deficiency has been associated with performance decrements in numerous laboratory and field-based studies."

The researchers found that despite NASA's recommendation that astronauts get at least 8.5 hours of sleep per night, crew members in training slept for less than six hours, while those in flight slept for about 6.09 hours on an average.

Another major find of the study was that astronauts were using sleeping pills such as zolpidem and zaleplon. Around 78 percent of shuttle-mission crew members used medication on 52 percent of flights.

Sleep-medication usage during space flights is problematic because research has shown that these drugs affect problem-solving abilities.

"The ability for a crew member to optimally perform if awakened from sleep by an emergency alarm may be jeopardized by the use of sleep-promoting pharmaceuticals," said Barger in a news release.

The researchers said that this study shows that it is important to promote healthy sleeping habits in astronauts. Future missions to Mars or beyond would require people who can cope with living in space for extended periods of time. Some measures such as exposure to specific wavelength of light could help regulate sleep pattern in space.

The study is published in the journal The Lancet Neurology. 

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Simulated mission shows sleep needs of astronauts

An interesting article discussing the sleep needs of astronauts during space missions.

In the first study of its kind, a team of researchers led by faculty at the Perelman School of Medicine at the University of Pennsylvania and the Baylor College of Medicine, has analyzed data on the impact of prolonged operational confinement on sleep, performance, and mood in astronauts from a groundbreaking international effort to simulate a 520-day space mission to Mars.

The findings, published online-first in the Proceedings of the National Academy of Sciences, revealed alterations of life-sustaining sleep patterns and neurobehavioral consequences for crew members that must be addressed for successful adaption to prolonged space missions.

"The success of human interplanetary spaceflight, which is anticipated to be in this century, will depend on the ability of astronauts to remain confined and isolated from Earth much longer than previous missions or simulations," said David F. Dinges, PhD, professor and chief, Division of Sleep and Chronobiology in the Department of Psychiatry at the Perelman School of Medicine, and co-lead author of the new study. "This is the first investigation to pinpoint the crucial role that sleep-wake cycles will play in extended space missions."

The 520-day simulation, which was developed by the Institute for Biomedical Problems (IBMP) of the Russian Academy of Sciences, and sponsored in part by the European Space Agency (ESA), was initiated on June 3, 2010 when the hatches were closed on a 550-cubic-meter IBMP spacecraft-like confinement facility in Russia. The simulated mission, involving an international, six-man team of volunteers, involved more than 90 experiments and realistic scenarios to gather valuable psychological and medical data on the effects of a long-term deep space flight. The 520-day mission was broken into three phases: 250 days for the trip to Mars, 30 days on the surface, and 240 days for the return to Earth.

As the only U.S. research team involved with the Mars 520-day simulation, the study authors monitored the crew's rest-activity patterns, and performance and psychological responses to determine the extent to which sleep loss, fatigue, stress, mood changes and conflicts occurred during the mission.

Measurements included continuous recordings of body movements using wrist actigraphy (a noninvasive means of estimating sleep and movement intensity), and light exposure and weekly computer-based neurobehavioral assessments to identify changes in the crew's activity levels, sleep quantity and quality, sleep-wake intervals, alertness performance, and workload throughout the 17 months of mission confinement.

Data from the actigraph devices revealed that crew sedentariness increased across the mission, as illustrated by decreased waking movement and increased sleep and rest times. The majority of crewmembers also experienced one or more disturbances of sleep quality, alertness deficits, or altered sleep-wake intervals and timing, suggesting inadequate circadian synchronization.

"Taken together, these measurements point to the need to identify markers of differential vulnerability to abnormal decrease in muscular movement and sleep- wake changes in crew members during the prolonged isolation of exploration spaceflight and the need to ensure maintenance of the Earth's natural circadian rhythm, sleep quantity and quality, and optimal activity levels during exploration missions," said Mathias Basner, MD, PhD, MSc, assistant professor of Sleep and Chronobiology in Psychiatry at Penn and co-lead author.

The research team concludes that successful adaptation to such missions will require crews to transit in spacecraft and live in surface habitats that artificially mimic aspects of Earth's sleep-wake activity cycles, such as appropriately timed light exposure, food intake, and exercise. This dynamic will be necessary to maintain neurocognition and human behavior throughout the flight.

The findings also have implications for the increasing prevalence of sleep and circadian rhythm disorders in mainstream society. The research team notes that many people in industrialized societies exist with sedentary lifestyles, prolonged artificial light exposure, and disruptions in healthy sleep patterns due to education and work schedules, leading to other comorbid health conditions such as obesity.

"A takeaway message from this line of research is the life-sustaining importance that healthy sleep duration and timing plays for everyone," Dinges said. "As a global society, we need to reevaluate how we view sleep as it relates to our overall health and ability to lead productive lives. Whether it is an astronaut being challenged to reach another planet or a newborn baby just learning to walk, the human body's need for sleep is as essential as our need for food and water and integral to our ability to thrive."

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Space Travel May Harm Brain: Cosmic Radiation Exposure May Quicken Alzheimer's Progression

This interesting article discusses how space travel may be harmful for the brain and how the prolonged exposure to cosmic radiation could make Alzheimer's appear more quickly.

As if space travel was not already filled with enough dangers, a new study out today in the journal PLOS ONE shows that cosmic radiation -- which would bombard astronauts on deep space missions to places like Mars -- could accelerate the onset of Alzheimer's disease.

"Galactic cosmic radiation poses a significant threat to future astronauts," said M. Kerry O'Banion, M.D., Ph.D., a professor in the University of Rochester Medical Center (URMC) Department of Neurobiology and Anatomy and the senior author of the study. "The possibility that radiation exposure in space may give rise to health problems such as cancer has long been recognized. However, this study shows for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer's disease."

While space is full of radiation, the earth's magnetic field generally protects the planet and people in low earth orbit from these particles. However, once astronauts leave orbit, they are exposed to constant shower of various radioactive particles. With appropriate warning, astronauts can be shielded from dangerous radiation associated with solar flares. But there are also other forms of cosmic radiation that, for all intents and purposes, cannot be effectively blocked.

Because this radiation exists in low levels, the longer an astronaut is in deep space, the greater the exposure. This is a concern for NASA as the agency is planning manned missions to a distant asteroid in 2021 and to Mars in 2035. The round trip to the red planet, in particular, could take as long as three years.

For over 25 years, NASA has been funding research to determine the potential health risks of space travel in an effort to both develop countermeasures and determine whether or not the risks warranted sending men and women on extended missions in deep space.

Since that time, several studies have demonstrated the potential cancer, cardiovascular, and musculoskeletal impact of galactic cosmic radiation. The study out today for the first time examines the potential impact of space radiation on neurodegeneration, in particular, the biological processes in the brain that contribute to the development of Alzheimer's disease. O'Banion -- whose research focuses on how radiation affects the central nervous system -- and his team have been working with NASA for over eight years.

The researchers studied the impact of a particular form of radiation called high-mass, high-charged (HZE) particles. These particles -- which are propelled through space at very high speeds by the force of exploding stars -- come in many different forms. For this study the researcher chose iron particles. Unlikely hydrogen protons, which are produced by solar flares, the mass of HZE particles like iron, combined with their speed, enable them to penetrate solid objects such as the wall and protective shielding of a spacecraft.

"Because iron particles pack a bigger wallop it is extremely difficult from an engineering perspective to effectively shield against them," said O'Banion. "One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete."

A portion of the research was conducted at the NASA Space Radiation Laboratory at Brookhaven National Laboratory on Long Island. NASA located its research operation at Brookhaven to take advantage of the Lab's particle accelerators which -- by colliding matter together at very high speeds -- can reproduce the radioactive particles found in space.

The researchers specifically wanted to examine whether or not radiation exposure had the potential to accelerate the biological and cognitive indicators of Alzheimer's disease, particularly in individuals who may be predisposed to developing the disease. To accomplish this they chose study the impact on animal models of Alzheimer's disease. These particular models have been extensively studied and scientists understand the precise timeframe in which the disease progresses over time.

At Brookhaven, the animals were exposed to various doses of radiation, including levels comparable to what astronauts would be experience during a mission to Mars. Back in Rochester, a team of researchers -- including URMC graduate student Jonathan Cherry, who was first author on the paper -- evaluated the cognitive and biological impact of the exposure. The mice underwent a series of experiments during which they had to recall objects or specific locations. The researchers observed that mice exposed to radiation were far more likely to fail these tasks -- suggesting neurological impairment -- earlier than these symptoms would typically appear.

The brains of the mice also showed signs of vascular alterations and a greater than normal accumulation of beta amyloid, the protein "plaque" that accumulates in the brain and is one of the hallmarks of the disease.

"These findings clearly suggest that exposure to radiation in space has the potential to accelerate the development of Alzheimer's disease," said O'Banion. "This is yet another factor that NASA, which is clearly concerned about the health risks to its astronauts, will need to take into account as it plans future missions."

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