282 Effect of circadian misalignment on the sleep of police officers across a series of night shifts

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A113-A113
Author(s):  
Anastasi Kosmadopoulos ◽  
Laura Kervezee ◽  
Philippe Boudreau ◽  
Diane Boivin
Keyword(s):  
Police Officers ◽  
Work Conditions ◽  
Night Work ◽  
Circadian Misalignment ◽  
Daytime Sleep ◽  
Circadian Phase ◽  
Work Cycle ◽  
Before And After ◽  
A Cell ◽  
Night Shifts

Abstract Introduction Misalignment of behavior and circadian rhythms due to night work can impair sleep and waking function. While both simulated and field-based studies suggest that circadian adaptation to a nocturnal schedule is slow, the rates of adaptation in real-world shift-work conditions are still largely unknown. The aim of this study was to evaluate the extent of adaptation of 24-h rhythms in 6-sulfatoxymelatonin (aMT6s) and cortisol in police officers across night shifts and to compare their effect on sleep. Methods A total of 76 police officers (20 women; aged 32.3±5.5 years, mean±SD) from the province of Québec, Canada, participated in a field study comprising their 28- or 35-day work-cycle. Urine samples were collected for ~24-h before and after a series of 3–7 night shifts. Rhythms of urinary aMT6s were considered adapted if midpoints following night shifts occurred during participants’ average daytime sleep period. Cortisol was considered adapted if midpoints occurred within 2h of their average daytime sleep offset. Sleep was measured with actigraphy and sleep logs on a cell phone. Data were analyzed with circular and linear mixed-effects models. Results Analyses were based on a subset of 37 participants with rhythms of both hormones suitable for circadian phase assessment before and after their series of night shifts. After night shifts, the group acrophase of adapted rhythms (aMT6: n=11, cortisol: n=9) occurred significantly later than for non-adapted rhythms (aMT6s: 10.9 h vs. 3.4 h, p<.001; cortisol: 14.9 vs. 9.9 h, p<.001). Participants with adapted aMT6s rhythms obtained cumulatively more sleep per day throughout the series of shifts than those with non-adapted rhythms (average 6.4 h per day vs 5.8 h per day; p=.026). Conclusion Consistent with prior research, our results from both urinary aMT6s and cortisol midpoints indicate that a large proportion of police officers remained in a state of circadian misalignment following their night shifts. The minority of officers who adapted to night work were able to obtain more sleep across consecutive night shifts. Support (if any) Project funded by the Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail (IRSST). A.K. received a postdoctoral fellowship from the Fonds de Recherche en Santé du Québec (FRQS).

scholarly journals P048: Profiling the burdens of working nights. Traditional 8-hour nights vs staggered 6-hour casino shifts in an academic emergency department

CJEM ◽  
2017 ◽  
Vol 19 (S1) ◽  
pp. S94
Author(s):  
A.X. Dong ◽  
M. Columbus ◽  
R. Arntfield ◽  
D. Thompson ◽  
M. Peddle
Keyword(s):  
Quality Of Life ◽  
Emergency Department ◽  
Night Shift ◽  
Night Work ◽  
Late Night ◽  
Before And After ◽  
Shift Model ◽  
The Impact ◽  
Night Shifts

Introduction: Emergency physicians (EP) often work at undesirable hours. In response to deleterious effects on quality of life for EPs, traditional 2300-0700 night shifts have been replaced at some centres with staggered 6-hour casino shifts (22:00-04:00 and 04:00-10:00). Though purported to allow for better sleep and recovery patterns, no evidence exists to support the benefits on sleep or quality of life that is used to justify a casino shift model. Using a before and after survey model, this study examines the impact of overhauling night work from a traditional 8-hour shift to casino shifts on the quality of life and job satisfaction of EPs working in an academic emergency department (ED). Methods: In 2010, an initial online, 37-item survey, was sent to all EPs working in the ED, just prior to the transition to casino shifts. 6 years following the transition, a slightly modified 37-item survey was again distributed to all current EPs working at that same centre. Participants rated their level of agreement on a 7-point Likert scale regarding questions related to night work. Results from the two surveys were compared. Results: 43 2010- and 47 2016-surveys were completed. In 2016, recovery to baseline function after a single early shift (22:00-04:00) was most common after 1 day at 52.4%, and after multiple early shifts was ≥2 days at 66.7%. Recovery after a single late shift (04:00-10:00) was most common at 1 day at 54.8%, and after multiple late shifts was ≥2 days at 59.5%. This was in contrast to 2010, when 55.8% recovered from a single traditional night shift after 1 day, and 95.3% required ≥2 days to recover from multiple traditional night shifts. In relation to casino shifts, 40.5% of respondents stated that night shifts are the greatest drawback of their job, compared to 79.1% previously. A minority of respondents felt that teaching (36.5%), diagnostic test interpretation (23.2%), and quality of handover (33.5%) were inferior on early and late night shifts compared to other shifts (74.4%, 58.1%, and 60.5% for traditional night shifts respectively).95.0% of respondents preferred casino over traditional night shifts. Conclusion: There were self-reported improvements in all domains following the implementation of casino shifts.

The relationship between chronotype and sleep behavior during rotating shift work: a field study

SLEEP ◽  
2021 ◽  
Author(s):  
Laura Kervezee ◽  
Fernando Gonzales-Aste ◽  
Phillipe Boudreau ◽  
Diane B Boivin
Keyword(s):  
Sleep Duration ◽  
Shift Work ◽  
Police Officers ◽  
Activity Cycle ◽  
Sleep Behavior ◽  
Shift Type ◽  
Work Cycle ◽  
Rotating Shift Work ◽  
The Relationship ◽  
Night Shifts

Abstract Shift work, an essential part of our 24/7 society, inevitably leads to displacement of the habitual sleep period and thereby to misalignment of the internal circadian timing system with the rest–activity cycle and the environment. How interindividual differences in circadian organization affect sleep duration and timing during rotating shift work is not fully understood. The objective of this study was to assess the effect of chronotype, shift type, and their interaction on actigraphy-based sleep behavior in 74 police officers (20 women and 54 men; age [mean ± SD]: 32.1 ± 5.4 years) involved in rotating shift work throughout a 28- to 35-day work cycle consisting of morning, evening, and night shifts. Using linear mixed modeling, we found that chronotype was associated with sleep duration depending on the shift type: increasing morningness was correlated with longer sleep duration during series of consecutive morning shifts, while increasing eveningness was correlated with longer sleep duration during series of evening shifts. During series of night shifts, increasing eveningness was associated with a longer duration of the main sleep episode, but this relationship was attenuated and no longer significant when naps were taken into account due to increased napping in morning chronotypes during series of night shifts. Providing a detailed within-subject characterization of sleep behavior across a complete work cycle consisting of morning, evening, and night shifts, this study advances the understanding of the relationship between chronotype and sleep in rotating shift workers and supports the implementation of work schedules that take into account chronobiological principles.

Daytime naps in darkness phase shift the human circadian rhythms of melatonin and thyrotropin secretion

2000 ◽  
Vol 278 (2) ◽  
pp. R373-R382 ◽  
Author(s):  
Orfeu M. Buxton ◽  
Mireille L'Hermite-Balériaux ◽  
Fred W. Turek ◽  
Eve van Cauter
Keyword(s):  
Circadian Rhythms ◽  
Phase Shift ◽  
Light Exposure ◽  
Caloric Intake ◽  
Stimulus Exposure ◽  
Blood Samples ◽  
Circadian Misalignment ◽  
Circadian Phase ◽  
Before And After ◽  
Dim Light

To systematically determine the effects of daytime exposure to sleep in darkness on human circadian phase, four groups of subjects participated in 4-day studies involving either no nap (control), a morning nap (0900–1500), an afternoon nap (1400–2000), or an evening nap (1900–0100) in darkness. Except during the scheduled sleep/dark periods, subjects remained awake under constant conditions, i.e., constant dim light exposure (36 lx), recumbence, and caloric intake. Blood samples were collected at 20-min intervals for 64 h to determine the onsets of nocturnal melatonin and thyrotropin secretion as markers of circadian phase before and after stimulus exposure. Sleep was polygraphically recorded. Exposure to sleep and darkness in the morning resulted in phase delays, whereas exposure in the evening resulted in phase advances relative to controls. Afternoon naps did not change circadian phase. These findings indicate that human circadian phase is dependent on the timing of darkness and/or sleep exposure and that strategies to treat circadian misalignment should consider not only the timing and intensity of light, but also the timing of darkness and/or sleep.

Efficacy of bright light and sleep/darkness scheduling in alleviating circadian maladaptation to night work

2001 ◽  
Vol 281 (2) ◽  
pp. E384-E391 ◽  
Author(s):  
Todd S. Horowitz ◽  
Brian E. Cade ◽  
Jeremy M. Wolfe ◽  
Charles A. Czeisler
Keyword(s):  
Shift Work ◽  
Night Shift ◽  
Bright Light ◽  
Night Work ◽  
Sleep Episode ◽  
Work Related ◽  
Before And After ◽  
Dim Light ◽  
Night Shifts ◽  
Better Than

We tested the hypothesis that circadian adaptation to night work is best achieved by combining bright light during the night shift and scheduled sleep in darkness. Fifty-four subjects participated in a shift work simulation of 4 day and 3 night shifts followed by a 38-h constant routine (CR). Subjects received 2,500 lux ( Bright Light) or 150 lux ( Room Light) during night shifts and were scheduled to sleep (at home in darkened bedrooms) from 0800 to 1600 ( Fixed Sleep) or ad libitum ( Free Sleep). Dim light melatonin onset (DLMO) was measured before and after the night shifts. Both Fixed Sleepand Bright Light conditions significantly phase delayed DLMO. Treatments combined additively, with light leading to larger phase shifts. Free Sleep subjects who spontaneously adopted consistent sleep schedules adapted better than those who did not. Neither properly timed bright light nor fixed sleep schedules were consistently sufficient to shift the melatonin rhythm completely into the sleep episode. Scheduling of sleep/darkness should play a major role in prescriptions for overcoming shift work-related phase misalignment.

Intermittent bright light and exercise to entrain human circadian rhythms to night work

1999 ◽  
Vol 277 (6) ◽  
pp. R1598-R1604 ◽  
Author(s):  
Erin K. Baehr ◽  
Louis F. Fogg ◽  
Charmane I. Eastman
Keyword(s):  
Circadian Rhythms ◽  
Intermittent Exercise ◽  
Bright Light ◽  
Phase Shifts ◽  
Night Work ◽  
Temperature Minimum ◽  
Daytime Sleep ◽  
Human Circadian Rhythms ◽  
Dim Light ◽  
Night Shifts

Bright light can phase shift human circadian rhythms, and recent studies have suggested that exercise can also produce phase shifts in humans. However, few studies have examined the phase-shifting effects of intermittent bright light, exercise, or the combination. This simulated night work field study included eight consecutive night shifts followed by daytime sleep/dark periods (delayed 9 h from baseline). There were 33 subjects in a 2 × 2 design that compared 1) intermittent bright light (6 pulses, 40-min long each, at 5,000 lx) versus dim light and 2) intermittent exercise (6 bouts, 15-min long each, at 50–60% of maximum heart rate) versus no exercise. Bright light and exercise occurred during the first 6 h of the first three night shifts. The circadian phase marker was the demasked rectal temperature minimum. Intermittent bright-light groups had significantly larger phase delays than dim-light groups, and 94% of subjects who received bright light had phase shifts large enough for the temperature minimum to reach daytime sleep. Exercise did not affect phase shifts; neither facilitating nor inhibiting phase shifts produced by bright light.

scholarly journals Beyond the limits of circadian entrainment: Non-24-hour sleep-wake disorder, shift work, and social jet lag

2021 ◽  
Author(s):  
Casey O Diekman ◽  
Amitabha Bose
Keyword(s):  
Shift Work ◽  
Bright Light ◽  
Light Therapy ◽  
Jet Lag ◽  
Mathematical Methods ◽  
Dark Cycle ◽  
Circadian Misalignment ◽  
Circadian Phase ◽  
Catch Up ◽  
Night Shifts

While the vast majority of humans are able to entrain their circadian rhythm to the 24-hour light-dark cycle, there are numerous individuals who are not able to do so due to disease or societal reasons. We use computational and mathematical methods to analyze a well-established model of human circadian rhythms to address cases where individuals do not entrain to the 24-hour light-dark cycle, leading to misalignment of their circadian phase. For each case, we provide a mathematically justified strategy for how to minimize circadian misalignment. In the case of non-24-hour sleep-wake disorder, we show why appropriately timed bright light therapy induces entrainment. With regard to shift work, we explain why reentrainment times following transitions between day and night shifts are asymmetric, and how higher light intensity enables unusually rapid reentrainment after certain transitions. Finally, with regard to teenagers who engage in compensatory catch-up sleep on weekends, we propose a rule of thumb for sleep and wake onset times that minimizes circadian misalignment due to this type of social jet lag. In all cases, the primary mathematical approach involves understanding the dynamics of entrainment maps that measure the phase of the entrained rhythm with respect to the daily onset of lights.

“The Greatest Thrill I Get is When I Hear a Criminal Say, ‘Yes, I Did it’”: Race and the Third Degree in New Orleans, 1920–1945

2016 ◽  
Vol 34 (1) ◽  
pp. 1-44
Author(s):  
Jeffrey S. Adler
Keyword(s):  
African American ◽  
Medical Care ◽  
New Orleans ◽  
Police Officer ◽  
Police Officers ◽  
Constitutional Protection ◽  
The Third ◽  
The Face ◽  
A Cell ◽  
Short Time

On May 11, 1938, two New Orleans policemen entered the Astoria Restaurant, marched to the kitchen, and approached Loyd D. T. Washington, a 41-year-old African American cook. They informed Washington that they would be taking him to the First Precinct station for questioning, although they assured the cook that he need not change his clothes and “should be right back” to the “Negro restaurant,” where he had worked for 3 years. Immediately after arriving at the station house, police officers “surrounded” Washington, showed him a photograph of a man, and announced that he had killed a white man in Yazoo City, Mississippi, 20 years earlier. When Washington insisted that he did not know the man in the photograph, that he had never been to (or even heard of) Yazoo City, and that he had been in the army at the time of the murder, the law enforcers confined him in a cell, although they had no warrant for his arrest and did not charge him with any crime. The following day, a detective brought him to the “show-up room” in the precinct house, where he continued the interrogation and, according to Washington, “tried to make me sign papers stating that I had killed a white man” in Mississippi. As every African American New Orleanian knew, the show-up (or line-up) room was the setting where detectives tortured suspects and extracted confessions. “You know you killed him, Nigger,” the detective roared. Washington, however, refused to confess, and the detective began punching him in the face, knocking out five of his teeth. After Washington crumbled to the floor, the detective repeatedly kicked him and broke one of his ribs. The beating continued for an hour, until other policemen restrained the detective, saying “give him a chance to confess and if he doesn't you may start again.” But Washington did not confess, and the violent interrogation began anew. A short time later, another police officer interrupted the detective, telling him “do not kill this man in here, after all he is wanted in Yazoo City.” Bloodied and writhing in pain, Washington asked to contact his family, but the request was ignored. Because he had not been formally charged with a crime, New Orleans law enforcers believed that Washington had no constitutional protection again self-incrimination or coercive interrogation and no right to an arraignment or bail, and they had no obligation to contact his relatives or to provide medical care for him.

Fatigue Monitoring and Management across Different Industries

2016 ◽  
Vol 60 (1) ◽  
pp. 993-996 ◽  
Author(s):  
Ranjana K. Mehta ◽  
S. Camille Peres ◽  
Linsey M. Steege ◽  
Jim R. Potvin ◽  
Mike Wahl ◽  
...  
Keyword(s):  
Risk Factor ◽  
Management Practices ◽  
Oil And Gas ◽  
Physiological State ◽  
Work Conditions ◽  
Severe Injuries ◽  
Circadian Phase ◽  
Current State ◽  
Fatigue Monitoring ◽  
Performance Capability

Fatigue, often defined as a physiological state of reduced mental or physical performance capability resulting from sleep loss, circadian phase, or workload (physical or cognitive), has been implicated as a critical risk factor resulting in severe injuries and accidents. A great deal of research has been done into the identification, measurement, and management of fatigue, however it is still poorly understood. This may be due to the characteristics and variability of work conditions across different industries; for example, fatigue in manufacturing is largely related to physical demands, and in aviation fatigue is related to sleep and shift-work. This panel will comprise of academics and practitioners across manufacturing, healthcare, transportation, aviation, and oil and gas industries. Topics covered within each industry will include fatigue causes and consequences, existing fatigue monitoring/management practices, barriers to fatigue monitoring and management, and recommendations/discussions around improving the current state.

Tracings of Behavior of Myoblasts Cultured Under Couette Type of Shear Flow Between Parallel Disks

2021 ◽  
Author(s):  
Shigehiro Hashimoto ◽  
Hiroki Yonezawa
Keyword(s):  
Shear Stress ◽  
Shear Flow ◽  
Rotating Disk ◽  
Time Lapse ◽  
Mechanical Stimuli ◽  
Parallel Disks ◽  
Before And After ◽  
A Cell

Abstract A cell deforms and migrates on the scaffold under mechanical stimuli in vivo. In this study, a cell with division during shear stress stimulation has been observed in vitro. Before and after division, both migration and deformation of each cell were analyzed. To make a Couette-type shear flow, the medium was sandwiched between parallel disks (the lower stationary culture-disc and the upper rotating disk) with a constant gap. The wall shear stress (1.5 Pa < τ < 2 Pa) on the surface of the lower culture plate was controlled by the rotational speed of the upper disc. Myoblasts (C2C12: mouse myoblast cell line) were used in the test. After cultivation without flow for 24 hours for adhesion of the cells to the lower disk, constant τ was applied to the cells in the incubator for 7 days. The behavior of each cell during shear was tracked by time-lapse images observed by an inverted phase contrast microscope placed in the incubator. Experimental results show that each cell tends to divide after higher activities: deformation and migration. The tendency is remarkable at the shear stress of 1.5 Pa.

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