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. 2022 Nov;73(4):e12826.
doi: 10.1111/jpi.12826. Epub 2022 Sep 5.

Effects of dynamic lighting on circadian phase, self-reported sleep and performance during a 45-day space analog mission with chronic variable sleep deficiency

Shadab A Rahman  1   2 , Brianne A Kent  1   2 , Leilah K Grant  1   2 , Toni Clark  3 , John P Hanifin  4 , Laura K Barger  1   2 , Charles A Czeisler  1   2 , George C Brainard  4 , Melissa A St Hilaire  1   2 , Steven W Lockley  1   2
Affiliations

Effects of dynamic lighting on circadian phase, self-reported sleep and performance during a 45-day space analog mission with chronic variable sleep deficiency

Shadab A Rahman et al. J Pineal Res. 2022 Nov.

Abstract

Spaceflight exposes crewmembers to circadian misalignment and sleep loss, which impair cognition and increase the risk of errors and accidents. We compared the effects of an experimental dynamic lighting schedule (DLS) with a standard static lighting schedule (SLS) on circadian phase, self-reported sleep and cognition during a 45-day simulated space mission. Sixteen participants (mean age [±SD] 37.4 ± 6.7 years; 5 F; n = 8/lighting condition) were studied in four-person teams at the NASA Human Exploration Research Analog. Participants were scheduled to sleep 8 h/night on two weekend nights, 5 h/night on five weekday nights, repeated for six 7-day cycles, with scheduled waketime fixed at 7:00 a.m. Compared to the SLS where illuminance and spectrum remained constant during wake (~4000K), DLS increased the illuminance and short-wavelength (blue) content of white light (~6000K) approximately threefold in the main workspace (Level 1), until 3 h before bedtime when illuminance was reduced by ~96% and the blue content also reduced throughout (~4000K × 2 h, ~3000K × 1 h) until bedtime. The average (±SE) urinary 6-sulphatoxymelatonin (aMT6s) acrophase time was significantly later in the SLS (6.22 ± 0.34 h) compared to the DLS (4.76 ± 0.53 h) and more variable in SLS compared to DLS (37.2 ± 3.6 min vs. 28.2 ± 2.4 min, respectively, p = .04). Compared to DLS, self-reported sleep was more frequently misaligned relative to circadian phase in SLS RR: 6.75, 95% CI 1.55-29.36, p = .01), but neither self-reported sleep duration nor latency to sleep was different between lighting conditions. Accuracy in the abstract matching and matrix reasoning tests were significantly better in DLS compared to SLS (false discovery rate-adjusted p ≤ .04). Overall, DLS alleviated the drift in circadian phase typically observed in space analog studies and reduced the prevalence of self-reported sleep episodes occurring at an adverse circadian phase. Our results support incorporating DLS in future missions, which may facilitate appropriate circadian alignment and reduce the risk of sleep disruption.

Keywords: circadian; dynamic lighting; light; melanopsin; melatonin; performance; sleep; spaceflight.

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Conflict of interest statement

Competing interests.

SAR holds patents for (1) Prevention of circadian rhythm disruption by using optical filters and (2) Improving sleep performance in subject exposed to light at night; SAR owns equity in Melcort Inc.; has provided paid consulting services to Sultan & Knight Limited, Bambu Vault LLC, Lucidity Lighting Inc.; and has received honoraria as an invited speaker and travel funds from Starry Skies Lake Superior, University of Minnesota Medical School, PennWell Corp., and Seoul Semiconductor Co. Ltd. These interests were reviewed and managed by Brigham and Women’s Hospital and Partners HealthCare in accordance with their conflict of interest policies. BAK, LKG, TC, report no conflicts. JPH reports being a paid consultant by Lutron, Inc. and McCullough Hill LLC. LKB reports personal fees from Boston Children’s Hospital, University of Helsinki and the AAA Foundation. CAC reports grants and contracts to BWH from Dayzz Live Well, Delta Airlines, Jazz Pharma, Puget Sound Pilots, Regeneron Pharmaceuticals/Sanofi; is/was paid consultant/speaker for Inselspital Bern, Institute of Digital Media and Child Development, Klarman Family Foundation, M. Davis and Co, National Council for Mental Wellbeing, National Sleep Foundation, Physician’s Seal, SRS Foundation, State of Washington Board of Pilotage Commissioners, Tencent, Teva Pharma Australia, With Deep, and Vanda Pharmaceuticals, in which CAC holds an equity interest; received travel support from Aspen Brain Institute, Bloomage International Investment Group, Inc., Dr. Stanley Ho Medical Development Foundation, German National Academy of Sciences, Ludwig-Maximilians-Universität München, National Highway Transportation Safety Administration, National Safety Council, National Sleep Foundation, Salk Institute for Biological Studies/Fondation Ipsen, Society for Research on Biological Rhythms, Stanford Medical School Alumni Association, Tencent Holdings, Ltd, and Vanda Pharmaceuticals; receives research/education gifts through BWH from Arbor Pharmaceuticals, Avadel Pharmaceuticals, Bryte, Alexandra Drane, Cephalon, DR Capital Ltd, Eisai, Harmony Biosciences, Jazz Pharmaceuticals, Johnson & Johnson, Mary Ann & Stanley Snider via Combined Jewish Philanthropies, NeuroCare, Inc., Optum, Philips Respironics, Regeneron, Regional Home Care, ResMed, Resnick Foundation (The Wonderful Company), San Francisco Bar Pilots, Sanofi SA, Schneider, Simmons, Sleep Cycle AB. Sleep Number, Sysco, Teva Pharmaceuticals, Vanda Pharmaceuticals; is/was an expert witness in legal cases, including those involving Advanced Power Technologies, Aegis Chemical Solutions, Amtrak; Casper Sleep Inc, C&J Energy Services, Catapult Energy Services Group, Covenant Testing Technologies, Dallas Police Association, Enterprise Rent-A-Car, Espinal Trucking/Eagle Transport Group/Steel Warehouse Inc, FedEx, Greyhound, Pomerado Hospital/Palomar Health District, PAR Electrical Contractors, Product & Logistics Services LLC/Schlumberger Technology, Puckett EMS, Puget Sound Pilots, Union Pacific Railroad, UPS, and Vanda Pharmaceuticals; serves as the incumbent of an endowed professorship given to Harvard by Cephalon; and receives royalties from McGraw Hill and Philips Respironics for the Actiwatch-2 and Actiwatch Spectrum devices. CAC’s interests were reviewed and are managed by the Brigham and Women’s Hospital and Mass General Brigham in accordance with their conflict-of-interest policies. GCB has no conflicts of interest relative to the scientific content of this manuscript. In the spirit of open disclosure, however, he reports having issued patents (USPTO 7678140 B2; 10603507; 10213619 B2 and 8366755 B2) and pending patents (USPTO 16/831737 and 16/657927) related to the photoreceptor system for melatonin regulation. That intellectual property has been licensed by Litebook Company Ltd. He has been a paid consultant by Lutron, Inc. and McCullough Hill LLC. He currently serves on a Scientific Advisory Board for PhotoPharmics. In addition, The Thomas Jefferson University’s Light Research Program (LRP) has received equipment donations from industry partners including Toshiba Materials, BIOS, Robern, and PhotoPharmics Company. The Philadelphia section of the IES, BIOS, Robern and Toshiba have made gifts to the LRP for programmatic, research and educational uses. MASH has provided limited consulting to The MathWorks, Inc. SWL (2018–2021) has received consulting fees from the BHP Billiton, EyeJust Inc., Lighting Science Group corporation/HealthE, Noble Insights, Rec Room, Six Senses, Stantec and Team C Racing; and has current consulting contracts with Akili Interactive, Apex 2100 Ltd., Consumer Sleep Solutions, Headwaters Inc., Hintsa Performance AG, KBR Wyle Services, Light Cognitive, Mental Workout/Timeshifter, and View Inc. He has received honoraria and travel or accommodation expenses from Bloxhub, Emory University, Estée Lauder, Ineos, MIT, Roxbury Latin School, and University of Toronto, and travel or accommodation expenses (no honoraria) from IES, Mental Workout, Solemma, and Wiley; and royalties from Oxford University Press. He holds equity in iSleep pty. He has received an unrestricted equipment gift from F. Lux Software LLC, a fellowship gift from Stockgrand Ltd and holds an investigator-initiated grant from F. Lux Software LLC and a Clinical Research Support Agreement and Clinical Trial Agreement with Vanda Pharmaceuticals Inc. He is an unpaid Board Member of the Midwest Lighting Institute (non-profit). He was a Program Leader for the CRC for Alertness, Safety and Productivity, Australia, through an adjunct professor position at Monash University (2015–2019). He is part-time adjunct professor at the University of Surrey, UK. He holds a pending patent for a ‘Method and system for generating and providing notifications for a circadian shift protocol’ (US20190366032A1). He has served as a paid expert in legal proceedings related to light, sleep and health.

Figures

Figure 1.
Figure 1.
Representative study protocol plotted in raster format. (A) participant 9332 from Mission 1 under the standard lighting schedule and (B) participant 8351 from Mission 5 under the dynamic lighting schedule. The black bars represent the scheduled sleep episode. The white bars represent wake under standard lighting. The blue, yellow and orange bars represent when the lighting was reduced in illuminance and short-wavelength content (6500K, 4100K and 2700K, respectively). The estimated aMT6s acrophase on scheduled sampling days are indicated by the red triangles and the interpolated daily acrophase of aMT6s is indicated by the red line. The timing of the cognitive battery is indicated by black circle marked with an x.
Figure 2.
Figure 2.
Effect of lighting schedule on circadian phase. Group average urinary 6-sulphatoxymelatonin (aMT6s) acrophase by lighting condition pre-, mid-, and end of mission (A) and across mission days (B). Data are expressed as the mean ± SEM. Urinary aMT6s acrophase times for each individual, separated by lighting condition (SLS or DLS) and mission (M) (C). Vertical dotted line (B, C) represents scheduled wake time. Vertical dashed lines (B, C) represent the interval within which the occurrence of aMT6s peak time was considered optimal (±1.0 SD from the mean in entrained individuals [33]). Collection started 15 days prior to the start of the mission (MD-15). Mission 2 was terminated on Mission Day = 22 due to Hurricane Harvey.
Figure 3.
Figure 3.
Self-reported sleep duration and sleep onset latency across the ~6-week mission. Data are shown as mean ± SE. Number of sleep records analyzed per condition – Weekday: SLS = 168, DLS: 232; Weekend: SLS = 78, DLS: 110. SLS: Standard Lighting Schedule, DLS: Dynamic Lighting Schedule.
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