To investigate the impact of the space environment on various aspects of astronaut health, including behavioral health and human factors and performance, NASA’s Human Research Program (HRP) and the National Space Biomedical Research Institute (NSBRI) have selected 24 proposals to fund. The selected proposals are from 21 institutions in 11 states and will receive a total of about $12.9 million during a 1- to 3-year period. All of the selected projects will contribute towards NASA’s future mission to Mars.

One study newly funded by NSBRI is “Sleep Electroencephalography and Near-Infrared Spectroscopy Measurements for Spaceflight and Analogs.” The study will be conducted by Gary Strangman, PhD, an associate professor at Harvard Medical School and director, Neural Systems Group at Massachusetts General Hospital. The study aims to develop, design, and test a near infrared spectroscopy-electroencephalography system for sleep research in order to measure and evaluate specific aspects of sleep in space.

Sleep and Astronaut Health

Strangman has been working with the NSBRI and NASA for over a decade, and he has come to understand that sleep can affect numerous aspects of human physiology and performance in spaceflight. It is often assumed that the sleep-related health risks faced by astronauts are similar to those faced by individuals on earth, such as performance errors and cognitive deficits. However, Strangman says, “Even relatively small changes in these parameters during spaceflight can have consequences that are significantly more serious than on Earth. There may also be unknown or synergistic effects of sleep loss in the spaceflight environment.”

In addition, astronauts experience sleep loss from demanding work schedules, a high-pressure and high-stakes work environment, and the need to phase-shift work schedules, Strangman says. Astronauts may also experience “significant circadian desynchrony, being exposed to a sunrise and sunset every 90 minutes while in orbit. These factors, combined with microgravity and other unique features of the spaceflight environment, often conspire to restrict astronauts’ sleep, not uncommonly requiring the use of sleep aids,” he says.

Objective measurement of sleep has been uncommon in astronauts largely due to technical challenges. The near infrared spectroscopy-electroencephalography system to be developed will provide solutions. Strangman says, “NINscan-M was originally conceived and designed as a multi-purpose data acquisition system for spaceflight biomedical applications, with a primary capability of NIRS imaging but also customizable for other uses.

“Our multi-use NINscan-M technology is easily adapted to provide measurement capabilities for such situations.”

New Technology

The NINscan-M being developed by Strangman and other researchers is a small, lightweight brain imaging system based on near-infrared spectroscopy (NIRS), which is suitable for spaceflight analog research or spaceflight, and features a 64-channel NIRS imaging and the capability to record 12-plus auxiliary data channels. For sleep research, a variety of physiological measures are typically included, such as cardiac activity, eye movements, and respiratory variables. The device in development will also incorporate these basic elements for research.

Strangman says, “In this new project, we plan to build upon our easy-to-use, spaceflight-compatible NINscan-M NIRS imaging system by incorporating collection of the variables that are essential to sleep research, resulting in a new version of the device, NINscan-S (for sleep).”

The new device’s sensor can be placed against any body part to collect hemodynamic imaging data and enables the measuring of blood oxygenation and blood volume in the periphery or in deeper tissues depending on the sensor configuration. Additional NINscan-M sensors enable measurement of accelerometry, temperature, and ECG, Strangman says, and the researchers will also investigate incorporating additional sensors or onboard algorithms to provide polysomnography (PSG)-like capabilities suitable for spaceflight.

Future Sleep Research

For the execution of this current project, the study will upgrade current NINscan device to support key PSG measurements as well as validate these measures against gold-standard measurements. In addition, the study will provide a feasibility test of the device in the Human Exploration Research Analog facility at NASA’s Johnson Space Center. Strangman says, “These tests will determine if the hardware and procedures are sufficiently simple for research volunteers to apply themselves—as will be necessary in spaceflight—and that the collected data is of sufficiently high quality to be useful for rigorous sleep studies.”

Strangman emphasizes the importance of addressing sleep-related issues in future space travel research. “Sleep concerns have been designated as one of the major risks in spaceflight, as per NASA’s Human Research Roadmap. Under this risk topic, NASA has currently identified 8 associated knowledge gaps that remain to be addressed,” Strangman says. “Essentially all research studies addressing these gaps could benefit from a more objective physiological assessment of sleep status in an easy to use form factor. This is the goal for adapting our NINscan-M to develop NINscan-S.”

Cassandra Perez is associate editor of Sleep Review. CONTACT [email protected]