Advanced Solid State Lighting for Human Evaluation

Lighting intensity and color have a significant impact on human circadian rhythms.  Advanced solid state lighting was developed for the Advanced Exploration System (AES) Deep Space Habitat (DSH) concept demonstrator.  The latest generation of assemblies using the latest commercially available LED lights were designed for use in the Bigelow Aerospace Environmental Control and Life Support System (ECLSS) simulator and the University of Hawaii's Hawaii Space Exploration Analog and Simulation (Hi-SEAS) habitat.  Agreements with both these organizations will allow the government to receive feedback on the lights and lighting algorithms from long term human interaction.

Sleep has a significant impact on the human circadian rhythm.  Bright light and blue light suppress the amount of melatonin, a sleep hormone, in the human organism.  The latest generation of advanced solid state lighting combines characteristics of normal terrestrial diurnal illumination with that of a normal crew day as scheduled by the AES DSH program.  Lighting goes from a twilight/nightlight mode and brightens as the crew goes through it's morning awakening activities.  The light becomes gradually brighter and cooler as crew approaches the nominal work day, maximum brightness peaking at a color temperature of 5500K.  As the work day comes to a close, and crew moves into their post work/social/rest period the light slightly dims and significantly warms approaching a color temperature of 3000K.  (Cool light corresponds to a greater color temperature and warmer light to a lower color temperature.)  When the crew prepares for the sleep cycle part of the day, the light dims yet to a twilight/nightlight state.

The current lights are fully addressable and  reprogrammable through a USB interface, allowing medical personnel to adjust each individual light to the needs of each crew members sleep needs.  Lighting can be gradually adjusted to assist with shifting crew circadian rhythm.  In the event on one member of the crew experiencing a sleep disorder, lights can be adjusted to assist with overcoming this difficulty - a lighting prescription.  Each light also has several preselected modes enabled through direct interaction with the fixture.

Agreements with the University of Hawaii and Bigelow Aerospace will allow the government to receive feedback on the current algorithms with minimal investment.  Hi-SEAS feedback from initial prototype units has already resulted in adjustments to the remote interface design.  It is expected feedback from human interaction will result in additional refinements to both the interface, lighting algorithm, and overall assembly.