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Hand AJ, Stone JE, Shen L, Vetter C, Cain SW, Bei B, Phillips AJK. Measuring light regularity: sleep regularity is associated with regularity of light exposure in adolescents. Sleep 2023; 46:zsad001. [PMID: 36625482 PMCID: PMC10424172 DOI: 10.1093/sleep/zsad001] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/30/2022] [Indexed: 01/11/2023] Open
Abstract
STUDY OBJECTIVES Light is the main time cue for the human circadian system. Sleep and light are intrinsically linked; light exposure patterns can influence sleep patterns and sleep can influence light exposure patterns. However, metrics for quantifying light regularity are lacking, and the relationship between sleep and light regularity is underexplored. We developed new metrics for light regularity and demonstrated their utility in adolescents, across school term and vacation. METHODS Daily sleep/wake and light patterns were measured using wrist actigraphy in 75 adolescents (54% male, 17.17 ± 0.83 years) over 2 weeks of school term and a subsequent 2-week vacation. The Sleep Regularity Index (SRI) and social jetlag were computed for each 2-week block. Light regularity was assessed using (1) variation in mean daily light timing (MLiT); (2) variation in daily photoperiod; and (3) the Light Regularity Index (LRI). Associations between SRI and each light regularity metric were examined, and within-individual changes in metrics were examined between school and vacation. RESULTS Higher SRI was significantly associated with more regular LRI scores during both school and vacation. There were no significant associations of SRI with variation in MLiT or daily photoperiod. Compared to school term, all three light regularity metrics were less variable during the vacation. CONCLUSIONS Light regularity is a multidimensional construct, which until now has not been formally defined. Irregular sleep patterns are associated with lower LRI, indicating that irregular sleepers also have irregular light inputs to the circadian system, which likely contributes to circadian disruption.
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Affiliation(s)
- Anthony J Hand
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Julia E Stone
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Lin Shen
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Céline Vetter
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA
| | - Sean W Cain
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Bei Bei
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Andrew J K Phillips
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
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2
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Role of Sleep Restriction in Daily Rhythms of Expression of Hypothalamic Core Clock Genes in Mice. Curr Issues Mol Biol 2022; 44:609-625. [PMID: 35723328 PMCID: PMC8929085 DOI: 10.3390/cimb44020042] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 12/12/2022] Open
Abstract
Lack of sleep time is a menace to modern people, and it leads to chronic diseases and mental illnesses. Circadian processes control sleep, but little is known about how sleep affects the circadian system. Therefore, we performed a 28-day sleep restriction (SR) treatment in mice. Sleep restriction disrupted the clock genes’ circadian rhythm. The circadian rhythms of the Cry1 and Per1/2/3 genes disappeared. The acrophase of the clock genes (Bmal1, Clock, Rev-erbα, and Rorβ) that still had a circadian rhythm was advanced, while the acrophase of negative clock gene Cry2 was delayed. Clock genes’ upstream signals ERK and EIFs also had circadian rhythm disorders. Accompanied by changes in the central oscillator, the plasma output signal (melatonin, corticosterone, IL-6, and TNF-α) had an advanced acrophase. While the melatonin mesor was decreased, the corticosterone, IL-6, and TNF-α mesor was increased. Our results indicated that chronic sleep loss could disrupt the circadian rhythm of the central clock through ERK and EIFs and affect the output signal downstream of the core biological clock.
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3
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Day-to-day reciprocal associations between depressive symptoms, cognitive performance, and sleep and the single-subject design. Int Psychogeriatr 2022; 34:7-9. [PMID: 34392871 DOI: 10.1017/s1041610221001149] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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4
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Fischer D, Hilditch CJ. Light in ecological settings: Entrainment, circadian disruption, and interventions. PROGRESS IN BRAIN RESEARCH 2022; 273:303-330. [DOI: 10.1016/bs.pbr.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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5
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Trivedi R, Man H, Madut A, Mather M, Elder E, Dhillon HM, Brand A, Howle J, Mann G, DeFazio A, Amis T, Cain SW, Phillips AJK, Kairaitis K. Irregular Sleep/Wake Patterns Are Associated With Reduced Quality of Life in Post-treatment Cancer Patients: A Study Across Three Cancer Cohorts. Front Neurosci 2021; 15:700923. [PMID: 34630009 PMCID: PMC8494030 DOI: 10.3389/fnins.2021.700923] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/31/2021] [Indexed: 01/20/2023] Open
Abstract
Background: Cancer patients often describe poor sleep quality and sleep disruption as contributors to poor quality of life (QoL). In a cross-sectional study of post-treatment breast, endometrial, and melanoma cancer patients, we used actigraphy to quantify sleep regularity using the sleep regularity index (SRI), and examined relationships with reported sleep symptoms and QoL. Methods: Participants were recruited post-primary treatment (35 diagnosed with breast cancer, 24 endometrial cancer, and 29 melanoma) and wore an actigraphy device for up to 2 weeks and SRI was calculated. Self-report questionnaires for cancer-related QoL [European Organization for Research and Treatment of Cancer EORTC (QLQ-C30)] were completed. Data were compared using analysis of variance (ANOVA) or Chi-Square tests. Multivariate linear regression analysis was used to determine independent variable predictors for questionnaire-derived data. Results: Age distribution was similar between cohorts. Endometrial and breast cancer cohorts were predominantly female, as expected, and body mass index (BMI) was higher in the endometrial cancer cohort, followed by breast and melanoma. There were no differences between tumor groups in: total sleep time, sleep onset latency, bedtime, and SRI (breast 80.9 ± 8.0, endometrial 80.3 ± 12.2, and melanoma 81.4 ± 7.0) (all p > 0.05). A higher SRI was associated with both better functional and symptom scores, including increased global QoL, better physical functioning, less sleepiness and fatigue, better sleep quality, and associated with less nausea/vomiting, dyspnea, and diarrhea (all p < 0.05). Conclusion: In cancer patients post-treatment, greater sleep regularity is associated with increased global QoL, as well as better physical functioning and fewer cancer related symptoms. Improving sleep regularity may improve QoL for cancer patients.
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Affiliation(s)
- Ritu Trivedi
- Ludwig Engel Centre for Respiratory Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - Hong Man
- Ludwig Engel Centre for Respiratory Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - Ayey Madut
- Ludwig Engel Centre for Respiratory Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - Marius Mather
- Sydney Informatics Hub, The University of Sydney, Camperdown, NSW, Australia
| | - Elisabeth Elder
- Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Westmead Breast Cancer Institute, Westmead Hospital, Westmead, NSW, Australia
| | - Haryana M Dhillon
- Centre for Medical Psychology and Evidence-Based Decision-Making, School of Psychology, Faculty of Science, The University of Sydney, Camperdown, NSW, Australia.,Psycho-Oncology Cooperative Research Group, School of Psychology, Faculty of Science, The University of Sydney, Camperdown, NSW, Australia
| | - Alison Brand
- Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Department of Gynecological Oncology, Westmead Hospital, Westmead, NSW, Australia
| | - Julie Howle
- Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Crown Princess Mary Cancer Centre, Westmead and Blacktown Hospitals, Sydney, NSW, Australia.,Melanoma Institute Australia, The University of Sydney, Sydney, NSW, Australia
| | - Graham Mann
- Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Melanoma Institute Australia, The University of Sydney, Sydney, NSW, Australia.,Centre for Cancer Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - Anna DeFazio
- Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Department of Gynecological Oncology, Westmead Hospital, Westmead, NSW, Australia.,Centre for Cancer Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia.,Sydney West Translational Cancer Research Centre, Westmead, NSW, Australia
| | - Terence Amis
- Ludwig Engel Centre for Respiratory Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia.,Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Sydney West Translational Cancer Research Centre, Westmead, NSW, Australia.,Department of Respiratory and Sleep Medicine, Westmead Hospital, Westmead, NSW, Australia
| | - Sean W Cain
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Andrew J K Phillips
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Kristina Kairaitis
- Ludwig Engel Centre for Respiratory Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia.,Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Sydney West Translational Cancer Research Centre, Westmead, NSW, Australia.,Department of Respiratory and Sleep Medicine, Westmead Hospital, Westmead, NSW, Australia
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6
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Murray JM, Magee M, Sletten TL, Gordon C, Lovato N, Ambani K, Bartlett DJ, Kennaway DJ, Lack LC, Grunstein RR, Lockley SW, Rajaratnam SMW, Phillips AJK. Light-based methods for predicting circadian phase in delayed sleep-wake phase disorder. Sci Rep 2021; 11:10878. [PMID: 34035333 PMCID: PMC8149449 DOI: 10.1038/s41598-021-89924-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/13/2021] [Indexed: 02/04/2023] Open
Abstract
Methods for predicting circadian phase have been developed for healthy individuals. It is unknown whether these methods generalize to clinical populations, such as delayed sleep-wake phase disorder (DSWPD), where circadian timing is associated with functional outcomes. This study evaluated two methods for predicting dim light melatonin onset (DLMO) in 154 DSWPD patients using ~ 7 days of sleep-wake and light data: a dynamic model and a statistical model. The dynamic model has been validated in healthy individuals under both laboratory and field conditions. The statistical model was developed for this dataset and used a multiple linear regression of light exposure during phase delay/advance portions of the phase response curve, as well as sleep timing and demographic variables. Both models performed comparably well in predicting DLMO. The dynamic model predicted DLMO with root mean square error of 68 min, with predictions accurate to within ± 1 h in 58% of participants and ± 2 h in 95%. The statistical model predicted DLMO with root mean square error of 57 min, with predictions accurate to within ± 1 h in 75% of participants and ± 2 h in 96%. We conclude that circadian phase prediction from light data is a viable technique for improving screening, diagnosis, and treatment of DSWPD.
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Affiliation(s)
- Jade M. Murray
- grid.1002.30000 0004 1936 7857Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, 18 Innovation Walk, Clayton, VIC 3800 Australia ,Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, NSW Australia
| | - Michelle Magee
- grid.1002.30000 0004 1936 7857Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, 18 Innovation Walk, Clayton, VIC 3800 Australia ,Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, NSW Australia ,grid.1008.90000 0001 2179 088XCentre for Neuroscience of Speech, Department of Audiology and Speech Pathology, University of Melbourne, Melbourne, VIC Australia
| | - Tracey L. Sletten
- grid.1002.30000 0004 1936 7857Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, 18 Innovation Walk, Clayton, VIC 3800 Australia ,Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, NSW Australia
| | - Christopher Gordon
- Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, NSW Australia ,grid.417229.b0000 0000 8945 8472Woolcock Institute of Medical Research and Sydney Local Health District, Sydney, NSW Australia ,grid.1013.30000 0004 1936 834XUniversity of Sydney Susan Wakil School of Nursing, Camperdown, NSW Australia
| | - Nicole Lovato
- Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,grid.1014.40000 0004 0367 2697Adelaide Institute for Sleep Health, College of Medicine and Public Health, Flinders University, Adelaide, SA Australia
| | - Krutika Ambani
- grid.1002.30000 0004 1936 7857Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, 18 Innovation Walk, Clayton, VIC 3800 Australia
| | - Delwyn J. Bartlett
- Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, NSW Australia ,grid.417229.b0000 0000 8945 8472Woolcock Institute of Medical Research and Sydney Local Health District, Sydney, NSW Australia
| | - David J. Kennaway
- grid.1010.00000 0004 1936 7304Robinson Research Institute and School of Medicine, University of Adelaide, Adelaide, SA Australia
| | - Leon C. Lack
- Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,grid.1014.40000 0004 0367 2697Adelaide Institute for Sleep Health, College of Medicine and Public Health, Flinders University, Adelaide, SA Australia
| | - Ronald R. Grunstein
- Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, NSW Australia ,grid.417229.b0000 0000 8945 8472Woolcock Institute of Medical Research and Sydney Local Health District, Sydney, NSW Australia
| | - Steven W. Lockley
- grid.1002.30000 0004 1936 7857Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, 18 Innovation Walk, Clayton, VIC 3800 Australia ,Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, NSW Australia ,grid.62560.370000 0004 0378 8294Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA USA ,grid.38142.3c000000041936754XDivision of Sleep Medicine, Harvard Medical School, Boston, MA USA
| | - Shantha M. W. Rajaratnam
- grid.1002.30000 0004 1936 7857Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, 18 Innovation Walk, Clayton, VIC 3800 Australia ,Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia ,NHMRC Centre for Sleep and Circadian Neurobiology, Sydney, NSW Australia ,grid.62560.370000 0004 0378 8294Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA USA ,grid.38142.3c000000041936754XDivision of Sleep Medicine, Harvard Medical School, Boston, MA USA
| | - Andrew J. K. Phillips
- grid.1002.30000 0004 1936 7857Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, 18 Innovation Walk, Clayton, VIC 3800 Australia ,Cooperative Research Centre for Alertness, Safety and Productivity, Clayton, VIC Australia
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Fischer D, Klerman EB, Phillips AJK. Measuring sleep regularity: Theoretical properties and practical usage of existing metrics. Sleep 2021; 44:6232042. [PMID: 33864369 PMCID: PMC8503839 DOI: 10.1093/sleep/zsab103] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/18/2021] [Indexed: 01/06/2023] Open
Abstract
STUDY OBJECTIVES Sleep regularity predicts many health-related outcomes. Currently, however, there is no systematic approach to measuring sleep regularity. Traditionally, metrics have assessed deviations in sleep patterns from an individual's average. Traditional metrics include intra-individual standard deviation (StDev), Interdaily Stability (IS), and Social Jet Lag (SJL). Two metrics were recently proposed that instead measure variability between consecutive days: Composite Phase Deviation (CPD) and Sleep Regularity Index (SRI). Using large-scale simulations, we investigated the theoretical properties of these five metrics. METHODS Multiple sleep-wake patterns were systematically simulated, including variability in daily sleep timing and/or duration. Average estimates and 95% confidence intervals were calculated for six scenarios that affect measurement of sleep regularity: 'scrambling' the order of days; daily vs. weekly variation; naps; awakenings; 'all-nighters'; and length of study. RESULTS SJL measured weekly but not daily changes. Scrambling did not affect StDev or IS, but did affect CPD and SRI; these metrics, therefore, measure sleep regularity on multi-day and day-to-day timescales, respectively. StDev and CPD did not capture sleep fragmentation. IS and SRI behaved similarly in response to naps and awakenings but differed markedly for all-nighters. StDev and IS required over a week of sleep-wake data for unbiased estimates, whereas CPD and SRI required larger sample sizes to detect group differences. CONCLUSIONS Deciding which sleep regularity metric is most appropriate for a given study depends on a combination of the type of data gathered, the study length and sample size, and which aspects of sleep regularity are most pertinent to the research question.
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Affiliation(s)
- Dorothee Fischer
- Sleep and Human Factors Research, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.,Division of Sleep and Circadian Disorders, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Elizabeth B Klerman
- Division of Sleep and Circadian Disorders, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA.,Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
| | - Andrew J K Phillips
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Melbourne, VIC, Australia
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8
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McHill AW, Sano A, Hilditch CJ, Barger LK, Czeisler CA, Picard R, Klerman EB. Robust stability of melatonin circadian phase, sleep metrics, and chronotype across months in young adults living in real-world settings. J Pineal Res 2021; 70:e12720. [PMID: 33523499 PMCID: PMC9135480 DOI: 10.1111/jpi.12720] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 01/24/2021] [Indexed: 01/26/2023]
Abstract
Appropriate synchronization of the timing of behaviors with the circadian clock and adequate sleep are both important for almost every physiological process. The timing of the circadian clock relative to social (ie, local) clock time and the timing of sleep can vary greatly among individuals. Whether the timing of these processes is stable within an individual is not well-understood. We examined the stability of circadian-controlled melatonin timing, sleep timing, and their interaction across ~ 100 days in 15 students at a single university. At three time points ~ 35-days apart, circadian timing was determined from the dim-light melatonin onset (DLMO). Sleep behaviors (timing and duration) and chronotype (ie, mid-sleep time on free days corrected for sleep loss on school/work days) were determined via actigraphy and analyzed in ~ 1-month bins. Melatonin timing was stable, with an almost perfect relationship strength as determined via intraclass correlation coefficients ([ICC]=0.85); average DLMO timing across all participants only changed from the first month by 21 minutes in month 2 and 5 minutes in month 3. Sleep behaviors also demonstrated high stability, with ICC relationship strengths ranging from substantial to almost perfect (ICCs = 0.65-0.85). Average DLMO was significantly associated with average chronotype (r2 = 0.53, P <.01), with chronotype displaying substantial stability across months (ICC = 0.61). These findings of a robust stability in melatonin timing and sleep behaviors in young adults living in real-world settings holds promise for a better understanding of the reliability of previous cross-sectional reports and for the future individualized strategies to combat circadian-associated disease and impaired safety (ie, "chronomedicine").
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Affiliation(s)
- Andrew W. McHill
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA, USA
- Division of Sleep Medicine, Department of Medicine, Harvard Medical School, Boston, MA, USA
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
| | - Akane Sano
- Affective Computing Group, Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical and Computer Engineering, Rice University, Houston, TX, USA
| | - Cassie J. Hilditch
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA, USA
- Division of Sleep Medicine, Department of Medicine, Harvard Medical School, Boston, MA, USA
- Fatigue Countermeasures Laboratory, Department of Psychology, San José State University, San Jose, CA, USA
| | - Laura K. Barger
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA, USA
- Division of Sleep Medicine, Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Charles A. Czeisler
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA, USA
- Division of Sleep Medicine, Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Rosalind Picard
- Affective Computing Group, Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Elizabeth B. Klerman
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA, USA
- Division of Sleep Medicine, Department of Medicine, Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
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9
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Cain SW, McGlashan EM, Vidafar P, Mustafovska J, Curran SPN, Wang X, Mohamed A, Kalavally V, Phillips AJK. Evening home lighting adversely impacts the circadian system and sleep. Sci Rep 2020; 10:19110. [PMID: 33154450 PMCID: PMC7644684 DOI: 10.1038/s41598-020-75622-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 10/14/2020] [Indexed: 01/08/2023] Open
Abstract
The regular rise and fall of the sun resulted in the development of 24-h rhythms in virtually all organisms. In an evolutionary heartbeat, humans have taken control of their light environment with electric light. Humans are highly sensitive to light, yet most people now use light until bedtime. We evaluated the impact of modern home lighting environments in relation to sleep and individual-level light sensitivity using a new wearable spectrophotometer. We found that nearly half of homes had bright enough light to suppress melatonin by 50%, but with a wide range of individual responses (0–87% suppression for the average home). Greater evening light relative to an individual’s average was associated with increased wakefulness after bedtime. Homes with energy-efficient lights had nearly double the melanopic illuminance of homes with incandescent lighting. These findings demonstrate that home lighting significantly affects sleep and the circadian system, but the impact of lighting for a specific individual in their home is highly unpredictable.
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Affiliation(s)
- Sean W Cain
- School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia.
| | - Elise M McGlashan
- School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Parisa Vidafar
- School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Jona Mustafovska
- School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Simon P N Curran
- School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Xirun Wang
- School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Anas Mohamed
- Department of Electrical and Computer Systems Engineering, School of Engineering, Monash University Malaysia, Bandar Sunway, 47500, Subang Jaya, Malaysia
| | - Vineetha Kalavally
- Department of Electrical and Computer Systems Engineering, School of Engineering, Monash University Malaysia, Bandar Sunway, 47500, Subang Jaya, Malaysia
| | - Andrew J K Phillips
- School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia.
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10
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Stone JE, McGlashan EM, Quin N, Skinner K, Stephenson JJ, Cain SW, Phillips AJK. The Role of Light Sensitivity and Intrinsic Circadian Period in Predicting Individual Circadian Timing. J Biol Rhythms 2020; 35:628-640. [PMID: 33063595 DOI: 10.1177/0748730420962598] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
There is large interindividual variability in circadian timing, which is underestimated by mathematical models of the circadian clock. Interindividual differences in timing have traditionally been modeled by changing the intrinsic circadian period, but recent findings reveal an additional potential source of variability: large interindividual differences in light sensitivity. Using an established model of the human circadian clock with real-world light recordings, we investigated whether changes in light sensitivity parameters or intrinsic circadian period could capture variability in circadian timing between and within individuals. Healthy participants (n = 12, aged 18-26 years) underwent continuous light monitoring for 3 weeks (Actiwatch Spectrum). Salivary dim-light melatonin onset (DLMO) was measured each week. Using the recorded light patterns, a sensitivity analysis for predicted DLMO times was performed, varying 3 model parameters within physiological ranges: (1) a parameter determining the steepness of the dose-response curve to light (p), (2) a parameter determining the shape of the phase-response curve to light (K), and (3) the intrinsic circadian period (tau). These parameters were then fitted to obtain optimal predictions of the three DLMO times for each individual. The sensitivity analysis showed that the range of variation in the average predicted DLMO times across participants was 0.65 h for p, 4.28 h for K, and 3.26 h for tau. The default model predicted the DLMO times with a mean absolute error of 1.02 h, whereas fitting all 3 parameters reduced the mean absolute error to 0.28 h. Fitting the parameters independently, we found mean absolute errors of 0.83 h for p, 0.53 h for K, and 0.42 h for tau. Fitting p and K together reduced the mean absolute error to 0.44 h. Light sensitivity parameters captured similar variability in phase compared with intrinsic circadian period, indicating they are viable targets for individualizing circadian phase predictions. Future prospective work is needed that uses measures of light sensitivity to validate this approach.
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Affiliation(s)
- Julia E Stone
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Australia
| | - Elise M McGlashan
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Australia
| | - Nina Quin
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Australia
| | - Kayan Skinner
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Australia
| | - Jessica J Stephenson
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Australia
| | - Sean W Cain
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Australia
| | - Andrew J K Phillips
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Australia
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