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Human Research Program

Blue Light for Enhancing Alertness in Space Missions

Completed Technology Project

Project Introduction

This is the final year of a directed research project that had reduced aims due to an unexpected funding reduction. The goal is to study the efficacy of blue or blue-enriched white solid-state light for enhancing alertness in men and women as a basis for developing an in-flight lighting countermeasure for enhancing alertness in astronauts and NASA ground crew. For this project, we have four 122 sq cm solid-state light sources: two with narrow-bandwidth (peak 469 nm) LEDs and two with broad-bandwidth blue-enriched LEDS that emit white-appearing light with a Correlated Color Temperature (CCT) of 6,500 K. These units provide a large, uniform light-emitting surface with intensity modulation. An independent safety analysis of both LED light sources based on national (American Conference of Industrial Hygienists (ACGIH)) and international (The International Commission on Non-Ionizing Radiation Protection (ICNIRP)) criteria has been completed. James Maida of Johnson Space Center (JSC) and Charles Bowen, Ph.D., of Lockheed Martin (retired) have confirmed that the blue LED units meet NASA's safety standards (West et al., 2008).

 

A melatonin suppression study was conducted with the narrow bandwidth blue LED units to characterize their biological potency and to guide the selection of the light intensity for the multiday alertness study. Healthy subjects (N=8) completed a total of 84 nighttime melatonin suppression experiments. Data analysis was completed showing that the blue LED light evokes a dose-response melatonin suppression, and permitting the calculation of a target intensity for the alertness study. The data also indicate that blue LED light is stronger than 4,000 K white fluorescent light for suppressing melatonin. A peer-review manuscript has been published on these results (West et al., 2011).

 

Over 300 individuals volunteered to be screened for a 3-day alertness study with the blue LED light units. From that pool of volunteers, 26 subjects completed all medical, psychological, and ophthalmological examinations as well as screens for stability of sleep-wake cycles and drugs of abuse. Of the 24 subjects that entered the study, 22 completed the three-day inpatient alertness protocol. Analysis of plasma melatonin, subjective alertness, objective alertness, and neurobehavioral data was finalized this year. Due to reduced funding, only a partial analysis of polysomnography data was completed. Two presentations have been made at international meetings describing the protocol and a partial analysis of the resultant data set (Hanifin et al., 2010a, 2010b). Preliminary testing of visual performance and color discrimination has been done with selected intensities of the narrow bandwidth blue LEDs with 8 healthy subjects. A pilot study on the consequences of reducing the size of the light-emitting surface to a more flight-worthy size was designed and approved by the Jefferson IRB. Two exposure systems with broad-bandwidth blue-enriched LEDS (6,500 K) were used for this study. Eight healthy male and female subjects completed all 24 nighttime experiments for this study.

 

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This is a historic project that was completed before the creation of TechPort on October 1, 2012. Available data has been included. This record may contain less data than currently active projects.

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