Book of Shift Patterns Vol:11

The rotations in working shifts disrupt natural sleep-wake cycle and eating patterns [ 1 ], which in turn cause serious health problems by affecting mental health and work effectiveness [ 2 ]. This disruption alters circadian rhythms [ 3 ] and neuronal functions to cause neuronal disorders [ 2 ].

Shiftwork for a long period increases the risk of fatigue, aggression, sleep disorders, metabolic disorders, mental abnormalities, and death [ 2 , 4 — 9 ].

Shiftwork directly affects alertness [ 10 , 11 ], causes depression, and promotes anxiety [ 12 ]. Working repeatedly during night shifts affects hormonal system and disrupts hormonal secretions and their control factors [ 13 — 16 ]. This altered hormonal profile increases the risk of breast cancer, prostate cancer, gastrointestinal abnormalities, cardiovascular diseases, and reproductive aberrations [ 17 — 19 ]. Alterations in physiological, behavioral, and psychological mechanisms [ 5 ] further develop abnormalities associated with peptic ulcer, diabetes type II, and rheumatoid arthritis [ 20 — 22 ].

The measurement of shiftwork is considered complex as it requires several parameters including sleep quality, fatigue level, types of sleep problems, use of stimulants, and sleepiness [ 2 , 23 ]. Shiftwork has gained huge importance which is inevitable in modern world.

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This situation alerts researchers to focus on shiftwork and related abnormalities. Without knowing the genetic mechanisms and identifying factors related to shiftwork-promoted health problems, development of prevention and curing strategies may not be achievable. Suitable model organism, monitoring systems, and mimicking the shiftwork in lab conditions are major challenges in studying shiftwork to investigate related disorders.

These challenges make the identification genes, majorly involved in shiftwork-related abnormalities, difficult. In this review, we have focused on major health problems that are linked with shiftwork directly or indirectly. Circadian rhythm mainly controls the daily wake and sleep cycle and regulates physiological processes including hormone secretion, body temperature, feeding behavior, cell cycle progression, and drug, glucose, and xenobiotic metabolism.

Its disruption through environmental and genetic means causes aberrations in physiological processes. Clock genes with the effects of oscillators and endocrine and neural signals regulate circadian rhythm [ 24 ] which may be disrupted apparently by shiftwork. Circadian clock, through appropriate physiological activities in relevance to time, controls the circadian rhythms [ 4 ]. Shiftwork chronic jet lag suppresses the expression levels of core clock genes, including Per1 and Per2 in suprachiasmatic nuclei SCN and MT1 melatonin and glucocorticoid receptors in the liver.

Besides clock genes, expression levels of some cell cycle-related genes including c-Myc and p53 are also altered [ 25 ]. Vasopressin V1a and V1b receptors expressed in SCN neurons promote shiftwork effect in combination with core clock genes. Circadian oscillator period is determined around 24 hours genetically and adjusted by synchronizers such as LD cycle. Circadian rhythms synchronized to day time work and night time sleep require phase adjustment in altered routines by central and peripheral oscillators.

This phase adjustment in certain cases disrupts the normal organization and sequence of the clock. Clock genes behave differently during phase shifts [ 1 , 27 ]. Shift workers undergo circadian dysrhythmia that adversely effects mental health. This further leads to circadian rhythm disorder causing aberrations in neurogenesis and spatial cognition [ 28 ]. Many aspects of circadian rhythmicity can be modulated by serotonergic agents that indicate that serotonin is involved in the regulation of circadian rhythm. Significant associations between shiftwork and S variant of the SLC6A4 promoter and 5-HT and 5-HIAA contents of platelet can help in investigating the circadian rhythm-related mechanisms imposed by shiftwork [ 29 ].

The effect of shiftwork on circadian rhythm and sleep may cause the metabolic dysregulation and depressions by affecting the genetic pathways. It is controlled genetically with the influence of environmental factors [ 31 , 32 ]. Adenosine, a sleep-promoting molecule [ 33 ], mediates wake-promoting effects of caffeine by acting on adenosine receptors antagonistically [ 34 ]. GABA gamma-aminobutyric acid promotes sleep whereas dopamine, acetylcholine, norepinephrine, and histamine promote wakefulness [ 35 ].

All these genes and regulators may get disrupted in shift workers which will lead to abnormal sleep and other serious health conditions. Furthermore, the shiftwork-induced deficits in sleep homeostasis and circadian rhythms may lead to different psychiatric disorders and affect SUR2 gene, which was found involved in energy metabolism and aetiology of cardiomyopathies [ 41 ]. Shiftwork may disrupt daily patterns of human physiology controlled by circadian rhythms and sleep, including regulation of energy patterns expenditure [ 42 , 43 ] and glucose metabolism [ 42 ]. The disrupted functions of the above genes through shiftwork may lead to related disorders.

Widening its effectiveness, shiftwork promotes acute coronary syndrome [ 52 ], menstrual disturbances, and abnormal insulin levels [ 53 ] and increases sleepiness and alcohol consumption [ 54 ]. It also lifts sleep deprivation that ultimately leads to loss in cognitive, physical, and metabolic consequences. These alterations can possibly end up with developing cardiovascular morbidity and mortality [ 29 ]. Social jet lag is a key player in developing metabolic syndrome by inducing changes in cholesterol levels and disrupting normal food processes.

It was observed in an experiment that social jet lag potentiated body weight gain by increasing overconsumption of cafeteria food. As a result, it promoted high insulin and dyslipidemia indicating the risk of metabolic syndrome [ 55 ]. It changes the expression profiles of metabolic genes in liver [ 56 ]. This alteration affects metabolic processes including carbohydrate and lipid utilization in liver. Carbohydrate regulators affected were insulin receptor substrate 2 Irs2 , glucose-responsive fork head box O1 Foxo1 , and glucose transporter 2 Slc2a2. These regulators control the functions of pyruvate carboxylase, the pyruvate transporter Slc16a7, pyruvate dehydrogenase kinase 4, the glycerol transporter aquaporin, fructose-2,6-biphosphatase 1, and liver pyruvate kinase.

These alterations in carbohydrate regulators further affect glycerol kinase and glycerol phosphate dehydrogenase 2, glutamic-pyruvate transaminase, and regulators of glycerol biosynthesis [ 4 ]. This dysregulation may induce critical alterations in genetic system to develop metabolic disorders. The presence of metabolic process controlling genes in rhythmic transcriptome indicates that alteration in circadian rhythm causes disruption in metabolic process [ 4 , 57 — 59 ].

Shiftwork brings about changes in appetitive hormones through circadian misalignment which causes reduction in leptin level that ultimately leads to weight gain. Shift workers are considered at higher risk of type II diabetes [ 42 , 62 ]. Quick return occurs due to rotations in between shifts, causing major accidents [ 22 ] that normally lead to death.

Shiftwork increases the risk of several disorders including mental disorders and sleep-related disorders, which may lead to death.

In an experiment related to jet lag effects on transgenic aged rats, it was found that mortality light scheduled rotations at 6 hours phase advance, each week. Although jet lag has no mortal effect on younger mice, it alters the behavior and circadian rhythms which further causes serious health issues by affecting brain and liver [ 7 ]. The role of SLC6A4 serotonin transporter gene in shift workers was confirmed to be related with time period. We also found a general trend of improved perceptions of satisfaction, less shift interference with personal schedules and decreased feelings of burnout.

On the other hand, the 48 hour on-shift requires firefighters to work a double shift, potentially necessitating 48 consecutive hours of work without sleep, as well as requiring firefighters to be away from families and personal responsibilities for 48 hours. Firefighters receive an inadequate amount of sleep during 24 hour shifts. The impact of work schedules on sleep quality or well-being has rarely been studied in this population. Secondary outcomes of interest included changes in professional and personal well-being, measured as feelings of burnout, time for personal schedules, job satisfaction and health habits.

The study was conducted in partnership with an American College of Surgeons verified Level I Trauma Center, and a large urban fire department that also provides Emergency Medical Services. After a brief assembly about the study in December , all personnel members of the fire department were subsequently sent surveys, sleep diaries, and consent forms in the mail.

Responses were submitted on paper and returned to the study coordinator through mail. Consent forms were provided with all surveys, although participants were also invited to complete the form anonymously without signing a consent form. Surveys and consent forms were returned to the Trauma Research Director via prepaid, return envelopes.

Data were maintained in a password-protected database. The printed form contained five questions and was estimated to take less than five minutes to complete per day. All sleep diary questions were developed by our research team. Participants were mailed a separate question self-reported survey before and after implementation of the new work schedule.

Secondary measures of interest included perceived interruptions in personal schedules five questions ; satisfaction five questions ; feelings of burnout six questions ; and health habits three questions. Age, gender, number of years in current job, whether or not respondent was a paramedic technician, and length of daily commute were also collected.

Dr Angela Moore

The survey was estimated to take 20 minutes to complete. Non-responders were sent one reminder post card, following the guidance of the Total Design Method. The ESS is a validated tool that was applied to assess general levels of daytime sleepiness by asking respondents how likely they are to doze off or fall asleep in eight different routine situations during the day.

Scores within a range of zero to ten on the ESS are considered normal; scores above ten are considered abnormal and reflect excessive daytime sleepiness. Each question was measured on a five-point scale, in which four indicated the highest degree of burnout. Questions gauging available time for personal schedules, satisfaction and health habits were designed by the research team and measured by a five-point likert scale, a seven-point likert scale and open-ended questions, respectively.

Secondary objectives included changes in professional and personal well-being, measured as changes in perceived interruptions in personal schedules due to work schedules, satisfaction, feelings of burnout, and health habits. Only matched responses to sleep diaries and self-reported surveys were incorporated in the study. Hours of sleep, number of interruptions, and the ESS scores were analyzed using paired sample t-tests to compare change in sleep quality before and after the shift implementation.

The results of nominal scales, including the refreshment scale and secondary variables of interest, were described pre and post schedule implementation.

The Lexical Typology of Semantic Shifts

There were few missing values; we did not substitute any missing values, thus, the total number of responses varies per question. There was no significant difference between respondents in the final analysis and all respondents included those with incomplete datasets ; demographic characteristics of participants and the total population are presented in table 1. There was a significant increase in mean hours of on-shift nightly sleep, from 5. The average number of hours slept per night during off-shift days was similar before and after the new shift was implemented 7.

There was a significant decrease in mean scores of daytime sleepiness, as measured by the ESS, from 8. Over half of participants 33 participants, We did not observe any significant changes in the average amount of time to fall asleep pre and post implementation. There was a general trend towards reduced burnout after implementation of the new schedule. After implementation, we observed a decrease in the proportion of participants that felt the shift interfered with responsibilities.

Additionally, there was not a large shift in responses regarding the frequency of thinking about quitting or the perceived difficulty working with patients. The majority of respondents The number of cigarettes smoked per week was unchanged; only one participant reported smoking cigarettes throughout the study. The consumption of alcoholic beverages per week remained unchanged 3.

The consumption of caffeinated beverages per day also remained constant 2. Fiscal Year Office Planner 20 Apr Academic Year Office Planner 9 Apr Fiscal Year Office Planner 9 Apr Calendar Year Office Planner 8 Apr Understanding Your Absence Rate 11 Jan Previous Page 1 2 Next Page.

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