Overview
Assessing the Impact of Chronic Sleep Restriction on Sleep and Performance-Associated Regional Brain Activation Using Near-Infrared Spectroscopy (First Award Fellowship)
Principal Investigator:
Michael L. Lee, Ph.D.
Organization:
Harvard-Brigham and Women's Hospital
Technical Summary
Astronauts and supporting ground crew personnel need to maintain high levels of physical and cognitive performance to ensure successful completion of space missions and safety of the astronauts. Astronauts and ground crews are often exposed to work challenges that are not conducive for restful sleep. Sleep loss can arise from shifting and extended work schedules that are commonly associated with space exploration. As a result, many astronauts are at risk for fatigue-related accidents that can endanger the success of space missions and personal safety. A major challenge in combating fatigue is accurate diagnosis. Subjective reporting of sleepiness is frequently significantly less than that obtained from objective measurements, indicating that self-diagnosis is inaccurate, even without including motivational reasons for an individual to report higher level of alertness than (s)he truly feels.
Preliminary evidence suggests that sleep deprivation reduces activation in the prefrontal cortex, which is known to be important for executive function and cognitive performance. A recently-developed technology, substantially developed with NSBRI support, allows for the quantification of oxygenated and de-oxygenated blood within the brain using near-infrared spectroscopy (NIRS). NIRS detects regional brain activity alterations associated with hemodynamic changes. Previous methodology for assessing hemodynamic levels required large, expensive functional magnetic resonance imaging (MRI) or positron emission tomography (PET) techniques that are impractical for use in space or most work environments. In contrast, NIRS technology is a highly portable and relatively inexpensive, and simple device for assessing regional brain activity.
This project will use NIRS to measure regional brain activation in the prefrontal cortex during performance testing and during sleep in participants experiencing chronic sleep restriction. The project will test the effects of sleep restriction at different circadian phases on prefrontal cortex activation during a cognitive performance task and during deep sleep. Results from this study can lead to the potential use of NIRS technology to objectively monitor sleepiness and reducing fatigue-related accidents.