To this end, we examined the circadian phase-shifting efficacy of exposure to short wavelength light throughout scheduled wake times on a protocol designed to simulate the schedule of crew members during the pre-launch quarantine period on a mission that requires an 8h phase advance of the sleep-wake schedule. Our goal was to demonstrate that exposure to ambient short wavelength fluorescent light would synchronize human circadian rhythms to a shifted sleep/wake schedule within 4-5 days, enhancing alertness and performance during the biological night.

During this proposed simulation sleep-wake schedules were advanced by 8h using 3 different schedule protocol designs: 1) a "slam" shift in which the sleep episode was abruptly advanced by 8h and then maintained for 4 days, 2) a gradual shift in which the sleep episode was advanced by 1.6h each day for 5 days until an 8h advance was achieved, and 3) a slam shift with naps in which the extended wake period prior to the 8h advance of the sleep period included 2 short nap opportunities. Given the prolonged extended wake period on the second day of the slam shift schedule, the new schedule involved the opportunity to obtain two short naps: one for 2h during the afternoon circadian dip, and the second for 4h at the circadian nadir during the night. A total of 43 participants were studied in the project. They were randomized to 1 of 5 protocol conditions which differed by light and by shift schedule. The 5 conditions were 1) white light slam shift, 2) green light slam shift, 3) combined white + green light slam shift with naps, 4) white light gradual shift, and 5) green light gradual shift.

Our specific aims were to test the hypotheses that: 1. Exposure to ambient polychromatic green light would be more effective than exposure to an equal illuminance of polychromatic white in shifting circadian rhythms, as measured by dim-light melatonin onset (DLMO), in response to both a gradual 8h advance and to an abrupt shift of their sleep-wake schedule. 2. Alertness and neurobehavioral performance in dim light on a constant routine (CR) during times at which crew members should be awake on the simulated mission would be significantly greater following 4-5 days of exposure to ambient polychromatic green light vs. ambient white light of equal illuminance, due to more effective circadian entrainment. 3. Alertness and neurobehavioral performance would be significantly better on the first night of exposure to ambient polychromatic short wavelength light vs. ambient white light of equal illuminance, prior to the induced circadian phase shifts, due to the immediate alerting effects of exposure to ambient polychromatic short wavelength light. 4. Sleep efficiency and total sleep time would be significantly increased and latency to persistent sleep and wake time after sleep onset would be significantly decreased during the sleep episode following 4-5 days of exposure to ambient polychromatic green light vs. ambient white light of equal illuminance, due to more effective circadian entrainment.

We predicted that exposure to polychromatic green light throughout the day would rapidly entrain the circadian melatonin rhythm to the shifted sleep-wake schedule. We also predicted that green light combined with brighter white to prevent the altered color-perception from the green light alone would enable implementation of this new technology to ensure circadian synchronization both during the pre-flight quarantine period and while aboard NASA flight vehicles. We predicted that our new schedule with naps would reduce the excessive daytime sleepiness and other adverse effects often experienced with the slam shift due to prolonged wakefulness. As per a supplemental grant (HPF00003), we implemented novel infra-red reflectance oculography technology into this protocol to detect fatigue, and collected data on eye movements in n=30 participants during periods of extended wake. New eye tracking technologies were implemented into the protocol, in order to examine causes of neurobehavioral deficits during periods of extended wake.

To this end, we propose to test the circadian phase-shifting efficacy of exposure to short wavelength light throughout scheduled wake times on a protocol designed to simulate the schedule of crew members during the pre-launch quarantine period on a mission that requires an 8h phase advance of the sleep-wake schedule. Our goal is to demonstrate that exposure to ambient short wavelength fluorescent light will synchronize human circadian rhythms to a shifted sleep/wake schedule within 4-5 days, enhancing alertness and performance during the biological night.

During this proposed simulation sleep-wake schedules will be advanced by 8h using 3 different protocol designs: 1) a "slam" shift in which the sleep episode is abruptly advanced by 8h and then maintained for 4 days, 2) a gradual shift in which the sleep episode is advanced by 1.6h each day for 5 days until an 8h advance is achieved, and 3) a "slam shift with naps in which the extended wake period prior to the 8h advance of the sleep period includes 2 short nap opportunities. Given the prolonged extended wake period on the second day of the slam shift schedule the new schedule involves the opportunity to obtain two short naps: one for 2h in the afternoon circadian dip, and the second for 4h at the circadian nadir during the night. A total of 44 subjects will be studied in the project. They will be randomized to 1 of 5 protocol conditions which differ by light and by shift. The 5 conditions are 1) white light slam shift, 2) green light slam shift, 3) combined white + green light slam shift with naps, 4) white light gradual shift, and 5) green light gradual shift.

Our specific aims are to test the hypotheses that:

1. exposure to ambient polychromatic green light from will be more effective than exposure to an equal illuminance of polychromatic white in shifting circadian rhythms, as measured by dim-light melatonin onset (DLMO), in response to both a gradual 8h advance and to an abrupt shift of their sleep-wake schedule.

2. alertness and neurobehavioral performance in dim light on a constant routine during times at which crew members should be awake on the simulated mission will be significantly greater following 4-5 days of exposure to ambient polychromatic green light vs. ambient white light of equal illuminance, due to more effective circadian entrainment.

3. alertness and neurobehavioral performance will be significantly better on the first night of exposure to ambient polychromatic short wavelength light vs. ambient white light of equal illuminance, prior to the induced circadian phase shifts, due to the immediate alerting effects of exposure to ambient polychromatic short wavelength light.

4. sleep efficiency and total sleep time will be significantly increased and latency to persistent sleep and wake time after sleep onset will be significantly decreased during the sleep episode following 4-5 days of exposure to ambient polychromatic green light vs. ambient white light of equal illuminance, due to more effective circadian entrainment.

We predict that exposure to polychromatic green light throughout the day will rapidly entrain the circadian melatonin rhythm to the shifted sleep-wake schedule. We also predict that green light combined with brighter white to prevent the altered color-perception from the green light alone will enable implementation of this new technology to ensure circadian synchronization both during the pre-flight quarantine period and while aboard NASA flight vehicles. We predict that our new schedule with naps will reduce the excessive daytime sleepiness and other adverse effects often experienced with the slam shift due to prolonged wakefulness.

To date, 37 subjects have completed the 8-day protocol. Four subjects completed the white light slam shift condition in order for us to determine the best level of illuminance (90 lux) to be used for both the white and polychromatic green light. To date, 10 subjects have completed the gradual shift protocol, in either white (n=5) or green light (n=5), 21 subjects have completed the slam shift protocol, in either white (n=10) or green light (n=11), and 6 subjects have completed the combined slam shift with naps protocol. We have completed the third year ahead of schedule for enrollment (11 subjects/year), and anticipate completing the study well in advance of the end of the project period. Melatonin samples, alertness and performance testing data, and sleep recording data were collected in these studies and are currently being analyzed to address our specific aims. As per a supplemental grant (HPF00003), we implemented novel infra-red technologies into this protocol, and collected data on eye movements in n=30 subjects during periods of extended wake. New eye tracking technologies have also been implemented into the protocol, in order to examine causes of neurobehavioral deficits during periods of extended wake.

To this end, we propose to test the circadian phase-shifting efficacy of exposure to short wavelength light throughout scheduled wake times on a protocol designed to simulate the schedule of crew members during the pre-launch quarantine period on a mission that requires an 8-hour phase advance of the sleep-wake schedule. Our goal is to demonstrate that exposure to ambient short wavelength fluorescent light will synchronize human circadian rhythms to a shifted sleep/wake schedule within 4-5 days, enhancing alertness and performance during the biological night.

During this proposed 8-day ground-based simulation, participants' sleep-wake schedules will be advanced by 8 hours. This advance shift will be done in 2 different protocol designs: 1) a "slam" shift in which the sleep episode is abruptly advanced by 8 hours and then maintained at this advanced time for 4 days, and 2) a gradual shift in which the sleep episode is advanced by 1.6 hours each day for 5 days until an 8 hour advance is achieved. A total of 44 subjects will be randomized to 1 of 4 protocol conditions which differ by light (ordinary indoor white light (~90 lux) or 90 lux polychromatic green light) and by shift (slam or gradual) resulting in 11 subjects/group. The 4 conditions are 1) white light slam shift, 2) green light slam shift, 3) white light gradual shift, and 4) green light gradual shift.

Our specific aims are to test the hypothesis that:

1. Exposure to ambient polychromatic short wavelength light from fluorescent lamps will be more effective than exposure to an equal illuminance of ambient polychromatic white light from standard fluorescent lamps in shifting the circadian rhythms of test subjects, as measured by dim-light melatonin onset (DLMO), in response to both a gradual 8-hour advance and to an abrupt shift of their sleep-wake schedule.

2. Alertness and neurobehavioral performance in dim light on a constant routine during times at which crew members should be awake on the simulated mission will be significantly greater following 4-5 days of exposure to ambient polychromatic green light vs. ambient white light of equal illuminance, due to more effective circadian entrainment.

3. Alertness and neurobehavioral performance will be significantly better on the first night of exposure to ambient polychromatic short wavelength light vs. ambient white light of equal illuminance, prior to the induced circadian phase shifts, due to the immediate alerting effects of exposure to ambient polychromatic short wavelength light.

4. Sleep efficiency and total sleep time will be significantly increased and latency to persistent sleep and wake time after sleep onset will be significantly decreased during the sleep episode following 4-5 days of exposure to ambient polychromatic green light vs. ambient white light of equal illuminance, due to more effective circadian entrainment.

We predict that, in contrast to white light, simple exposure to polychromatic green light throughout the day will rapidly (within five days) entrain the circadian melatonin rhythm to the shifted sleep-wake schedule, without the need for bright light exposure-rendering obsolete the crew quarters' bright light facility and enabling implementation of this new technology to ensure circadian synchronization both during the pre-flight quarantine period and while aboard NASA flight vehicles.

To date, 22 subjects have completed the 8-day protocol. Four subjects completed the white light slam shift condition in order for us to determine the best level of illuminance to be used for both the white and polychromatic green light. Melatonin samples, alertness and performance testing data, and sleep recording data were collected in these studies and are currently being analyzed to address our specific aims. Based on the melatonin results from the first 4 subjects, we proceeded to use a 90 lux level of illuminance, which is equivalent to that of ordinary indoor room light. We began randomizing enrolled subjects after completing the initial 4 subjects, with a further 18 subjects completing the protocol: 10 subjects have completed the gradual shift protocol, in either polychromatic white (n=5) or shorter-wavelength light (n=5), and 8 subjects have completed the slam shift protocol, in either polychromatic white light (n=3) or shorter-wavelength light (n=5).

As per the supplemental grant (HPF00003), we implemented novel infra-red technologies into this protocol. Eye movement data has been collected (n=15) during periods of extended wake, which will allow us to examine causes of neurobehavioral deficits during periods of extended wake.

We have completed the second year on target for enrollment (11 subjects/year), and anticipate remaining on target by the end of year 3.

To this end, we propose to test the circadian phase-shifting efficacy of exposure to short wavelength light throughout scheduled wake times on a protocol designed to simulate the schedule of crew members during the pre-launch quarantine period on a mission that requires an 8-hour phase advance of the sleep-wake schedule. Our goal is to demonstrate that exposure to ambient short wavelength fluorescent light will synchronize human circadian rhythms to a shifted sleep/wake schedule within 4-5 days, enhancing alertness and performance during the biological night.

During this proposed 8-day ground-based simulation, participants' sleep-wake schedules will be advanced by 8 hours. This advance shift will be done in 2 different protocol designs: 1) a "slam" shift in which the sleep episode is abruptly advanced by 8 hours and then maintained at this advanced time for 4 days, and 2) a gradual shift in which the sleep episode is advanced by 1.6 hours each day for 5 days until an 8 hour advance is achieved. A total of 44 subjects will be studied in the project. They will be randomized to 1 of 4 protocol conditions which differ by light (ordinary indoor white light (~90 lux) or 90 lux polychromatic green light) and by shift (slam or gradual) so that there will be 11 subjects/group. The 4 conditions are 1) white light slam shift, 2) green light slam shift, 3) white light gradual shift, and 4) green light gradual shift.

Our specific aims are to:

1. Test the hypothesis that exposure to ambient polychromatic short wavelength light from fluorescent lamps will be more effective than exposure to an equal illuminance of ambient polychromatic white light from standard fluorescent lamps in shifting the circadian rhythms of test subjects, as measured by dim-light melatonin onset (DLMO), in response to both a gradual 8-hour advance and to an abrupt shift of their sleep-wake schedule.

2. Test the hypothesis that alertness and neurobehavioral performance in dim light on a constant routine during times at which crew members should be awake on the simulated mission will be significantly greater following 4-5 days of exposure to ambient polychromatic green light vs. ambient white light of equal illuminance, due to more effective circadian entrainment.

3. Test the hypothesis that alertness and neurobehavioral performance will be significantly better on the first night of exposure to ambient polychromatic short wavelength light vs. ambient white light of equal illuminance, prior to the induced circadian phase shifts, due to the immediate alerting effects of exposure to ambient polychromatic short wavelength light.

4. Test the hypothesis that sleep efficiency and total sleep time will be significantly increased and latency to persistent sleep and wake time after sleep onset will be significantly decreased during the sleep episode following 4-5 days of exposure to ambient polychromatic green light vs. ambient white light of equal illuminance, due to more effective circadian entrainment.

We predict that, in contrast to white light, simple exposure to polychromatic green light throughout the day will rapidly (within five days) entrain the circadian melatonin rhythm to the shifted sleep-wake schedule, without the need for bright light exposure-rendering obsolete the crew quarters' bright light facility and enabling implementation of this new technology to ensure circadian synchronization both during the pre-flight quarantine period and while aboard NASA flight vehicles.

To date, 5 subjects have completed the 8-day protocol. Four subjects completed the white light slam shift condition in order for us to determine the best level of illuminance to be used for both the white and polychromatic green light. Melatonin samples, alertness and performance testing data, and sleep recording data were collected in these studies and are being analyzed to address our specific aims. Based on the melatonin results from these first 4 subjects, we have decided to use a 90 lux level of illuminance, which is equivalent to that of ordinary indoor room light. The polychromatic fluorescent lamps have been installed in our laboratory and calibrated so as to achieve 90 lux. We began randomizing enrolled subjects after completing the initial 4 subjects and 1 additional subject has completed the white light gradual shift condition, with 3 additional subjects scheduled to complete the study in April 2009.

We are continuing to enroll subjects and expect to be on target with enrollment (11 subjects/year) by the end of the first year of the project. In the coming year we anticipate being on or ahead of pace with at least 22 subjects completed by the end of year 2.

Recent advances over the past six years have revealed that the human circadian pacemaker is most sensitive to shorter wavelength (blue) light for both phase shifting and direct enhancement of alertness and performance. While the monochromatic blue (~460 nm) light used for research is not a practical spaceflight countermeasure because of its adverse effects on color vision, we have shown blue-enriched white light to facilitate circadian phase shifts.

This project will test the efficacy of exposure to blue-enriched light at a standard intensity for pre-launch and inflight phase shifting. During this ground-based simulation of the pre-launch quarantine period, participants sleep-wake schedules will be shifted (advanced) by eight hours. Groups (n=16 subjects/light condition) will be randomized to four-day exposures to either: ordinary indoor white light (~50 lux) or 50 lux polychromatic blue-enriched light.

We predict that, in contrast to white light, simple exposure to blue-enriched light throughout the day will rapidly (within four days) entrain the circadian melatonin rhythm to the shifted sleep-wake schedule without the need for bright light exposure rendering obsolete the crew quarters bright-light facility and enabling implementation of this new technology to ensure circadian synchronization both during the preflight quarantine period and while aboard NASA flight vehicles.