Shift work is an employment practice designed to keep a service or production line operational at all times . The practice typically sees the day divided into shifts, set periods of time during which different groups of workers perform their duties. The term "shift work" includes both long-term night shifts and work schedules in which employees change or rotate shifts.
90-471: [REDACTED] Look up swing shift in Wiktionary, the free dictionary. Swing Shift may refer to: The shift between the day and night shifts. Swing Shift (album) , a 1997 jazz album by Rik Emmett Swing Shift (film) , a 1984 film by Jonathan Demme Swing Shift , a stop motion short film by Mike Jittlov "Swing Shift (Soixante Neuf)",
180-655: A growth inhibitor on fungal pathogens including Alternaria , Botrytis , and Fusarium spp. Decreases the speed of infection. As a seed treatment , protects Lupinus albus from fungi. Dramatically slows Pseudomonas syringae tomato DC3000 infecting Arabidopsis thaliana and infecting Nicotiana benthamiana . Melatonin has been observed to reduce stress tolerance in Phytophthora infestans in plant-pathogen systems. Danish pharmaceutical company Novo Nordisk have used genetically modified yeast ( Saccharomyces cerevisiae ) to produce melatonin. Melatonin
270-415: A leaving group when attacked by a general base, producing N -acetylserotonin. The final step in the biosynthesis of melatonin involves the methylation of N -acetylserotonin at the hydroxyl position by SAM, resulting in the production of S -adenosyl homocysteine (SAH) and melatonin. In vertebrates, the secretion of melatonin is regulated through the activation of the beta-1 adrenergic receptor by
360-625: A biological signal for the organization of daylength-dependent ( photoperiodic ) seasonal functions such as reproduction, behavior, coat growth, and camouflage coloring in seasonal animals. In seasonal breeders that do not have long gestation periods and that mate during longer daylight hours, the melatonin signal controls the seasonal variation in their sexual physiology, and similar physiological effects can be induced by exogenous melatonin in animals including mynah birds and hamsters. Melatonin can suppress libido by inhibiting secretion of luteinizing hormone and follicle-stimulating hormone from
450-488: A growth regulator, as well as environmental stress protector. It is synthesized in plants when they are exposed to both biological stresses, for example, fungal infection, and nonbiological stresses such as extremes of temperature, toxins, increased soil salinity , drought, etc. Herbicide -induced oxidative stress has been experimentally mitigated in vivo in a high-melatonin transgenic rice . Studies conducted on lettuce grown in saline soil conditions have shown that
540-537: A large part of shift worker. Several companies run twenty-four-hour shifts. Most of the work is done during the day. When the work dries up, it usually is the second and third shift workers who pay the price. They are told to punch out early or use paid time off if they have any to make up the difference in their paychecks. That practice costs the average worker $ 92.00 a month. Melatonin may increase sleep length during both daytime and nighttime sleep in people who work night shifts. Zopiclone has also been investigated as
630-465: A link between fatigue and workplace injuries and accidents. Workers with sleep deprivation are far more likely to be injured or involved in an accident. Breaks reduce accident risks. One study suggests that, for those working a night shift (such as 23:00 to 07:00), it may be advantageous to sleep in the evening (14:00 to 22:00) rather than the morning (08:00 to 16:00). The study's evening sleep subjects had 37% fewer episodes of attentional impairment than
720-495: A minimum of 10 hours between shifts is an effective strategy to encourage adequate sleep for workers. Allowing frequent breaks and scheduling 8- or 10-hour shifts instead of 12-hour shifts can also minimize fatigue and help to mitigate the negative health effects of shift work. Multiple factors need to be considered when developing optimal shift work schedules, including shift timing, length, frequency and length of breaks during shifts, shift succession, worker commute time, as well as
810-481: A potential treatment, but it is unclear if it is effective in increasing daytime sleep time in shift workers. There are, however, no reports of adverse effects. Modafinil and R-modafinil are useful to improve alertness and reduce sleepiness in shift workers. Modafinil has a low risk of abuse compared to other similar agents. However, 10% more participants reported adverse effects (nausea and headache) while taking modafinil. In post-marketing surveillance, modafinil
900-432: A shift system. Rotation of shifts can be fast, in which a worker changes shifts more than once a week, or slow, in which a worker changes shifts less than once a week. Rotation can also be forward, when a subsequent shift starts later, or backward, when a subsequent shift starts earlier. Evidence supports forward rotating shifts are more adaptable for shift workers' circadian physiology. One main concern of shift workers
990-588: A shift-bidding mechanism. Through this process, the shift hours are evened out by human-driven market mechanism rather than an algorithmic process. This openness can lead to work hours that are tailored to an individual's lifestyle and schedule while ensuring that shifts are optimally filled, in contrast to the generally poor human outcomes of fatigue, stress, estrangement with friends and family and health problems that have been reported with algorithm-based scheduling of work-shifts. Mental (cognitive) fatigue due to inadequate sleep an/or disturbances of circadian rhythms
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#17328010296701080-702: A shortened lifespan. Women who worked rotating night shifts for more than 15 years also experienced a 25 percent higher risk of death due to lung cancer. Shift work also increases the risk of developing cluster headaches , heart attacks , fatigue , stress , sexual dysfunction , depression, dementia , obesity , metabolic disorders , gastrointestinal disorders , musculoskeletal disorders , and reproductive disorders. Shift work also can worsen chronic diseases, including sleep disorders , digestive diseases , heart disease , hypertension , epilepsy , mental disorders , substance abuse , asthma , and any health conditions that are treated with medications affected by
1170-486: A slow transfer of one electron from THB to molecular oxygen (O 2 ), potentially producing a superoxide ( O − 2 ). This superoxide could then recombine with the THB radical to form 4a-peroxypterin. 4a-peroxypterin may either react with the active site iron (II) to create an iron-peroxypterin intermediate or directly transfer an oxygen atom to the iron, facilitating the hydroxylation of L -tryptophan. Alternatively,
1260-619: A song by Nash the Slash on his album Children of the Night Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Swing Shift . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Swing_Shift&oldid=766268718 " Category : Disambiguation pages Hidden categories: Short description
1350-622: A substance from the pineal gland of cows that could induce skin lightening in common frogs . This compound was later identified as a hormone secreted in the brain during the night, playing a crucial role in regulating the sleep-wake cycle , also known as the circadian rhythm, in vertebrates . In vertebrates, melatonin's functions extend to synchronizing sleep-wake cycles, encompassing sleep-wake timing and blood pressure regulation , as well as controlling seasonal rhythmicity ( circannual cycle ), which includes reproduction, fattening, molting, and hibernation. Its effects are mediated through
1440-557: A system in many of the as yet 'free' branches of industry in Great Britain, in the blast-furnaces, forges, rolling mills and other metallurgical establishments of England, Wales and Scotland. The Cromford Mill , starting from 1772, ran day and night with two twelve-hour shifts. Shift work increases the risk for the development of many disorders. Shift work sleep disorder is a circadian rhythm sleep disorder characterized by insomnia , excessive sleepiness , or both. Shift work
1530-435: A very slow rotation in the petroleum industry . Twenty-four-hour shifts are common in health care and emergency services. The shift plan or rota is the central component of a shift schedule . The schedule includes considerations of shift overlap, shift change times and alignment with the clock, vacation, training, shift differentials, holidays, etc., whereas the shift plan determines the sequence of work and free days within
1620-452: A working day. There are many industries requiring 24/7 coverage that employ workers on a shift basis, including: Comprehensive Employment and Training Act Melatonin Melatonin , an indoleamine , is a natural compound produced by various organisms , including bacteria and eukaryotes . Its discovery in 1958 by Aaron B. Lerner and colleagues stemmed from the isolation of
1710-400: Is a common contributor to accidents and untoward incidents. While this risk cannot be eliminated, it can be managed through personal and administrative controls. This type of management is conducted through a Fatigue Risk Management System (FRMS). One method used within an FRMS is objective fatigue modeling to predict periods of high risk within a 24-hour shift plan. Missing income is also
1800-461: Is a greater risk of circadian rhythms disruption. Nighttime workers sleep an average of one–four hours less than daytime workers. Different shift schedules will have different impacts on the health of a shift worker. The way the shift pattern is designed affects how shift workers sleep, eat and take holidays. Some shift patterns can exacerbate fatigue by limiting rest, increasing stress, overworking staff or disrupting their time off. Muscle health
1890-682: Is also compromised by shift work: altered sleep and eating times, changes to appetite-regulating hormones and total energy expenditure, increased snacking and binge drinking, and reduced protein intake can contribute to negative protein balance, increases in insulin resistance and increases in body fat, resulting in weight gain and more long-term health challenges. Compared with the day shift, injuries and accidents have been estimated to increase by 15% on evening shifts and 28% on night shifts. Longer shifts are also associated with more injuries and accidents: 10-hour shifts had 13% more and 12-hour shifts had 28% more than 8-hour shifts. Other studies have shown
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#17328010296701980-468: Is also the norm in fields related to public protection and healthcare, such as law enforcement, emergency medical services , firefighting, security and hospitals. Shift work is a contributing factor in many cases of medical errors . Shift work has often been common in the armed forces . Military personnel, pilots, and others that regularly change time zones while performing shift work experience jet lag and consequently suffer sleep disorders. Those in
2070-627: Is considered essential for the diagnosis. The risk of diabetes mellitus type 2 is increased in shift workers, especially men. People working rotating shifts are more vulnerable than others. Women whose work involves night shifts have a 48% increased risk of developing breast cancer. This may be due to alterations in circadian rhythm: melatonin , a known tumor suppressor, is generally produced at night and late shifts may disrupt its production. The WHO's International Agency for Research on Cancer listed "shift work that involves circadian disruption" as probably carcinogenic. Shift work may also increase
2160-520: Is different from Wikidata All article disambiguation pages All disambiguation pages Shift work In medicine and epidemiology, shift work is considered a risk factor for some health problems in some individuals, as disruption to circadian rhythms may increase the probability of developing cardiovascular disease , cognitive impairment, diabetes , altered body composition and obesity , among other conditions. The shift work system in modern industrial manufacturing originated in
2250-524: Is knowing their schedule more than two weeks at a time. Shift work is stressful. When on a rotating or ever changing shift, workers have to worry about daycare, personal appointments, and running their households. Many already work more than an eight-hour shift. Some evidence suggests giving employees schedules more than a month in advance would give proper notice and allow planning, their stress level would be reduced. Though shift work itself remains necessary in many occupations, employers can alleviate some of
2340-467: Is often 25% to 40% lower on 2nd and 3rd shifts due to fixed costs which are "paid" by the first shift. The 42-hour work-week allows for the most even distribution of work time. A 3:1 ratio of work days to days off is most effective for eight-hour shifts, and a 2:2 ratio of work days to days off is most effective for twelve-hour shifts. Eight-hour shifts and twelve-hour shifts are common in manufacturing and health care. Twelve-hour shifts are also used with
2430-510: Is produced by α-proteobacteria and photosynthetic cyanobacteria. There is no report of its occurrence in archaea which indicates that melatonin originated in bacteria most likely to prevent the first cells from the damaging effects of oxygen in the primitive Earth's atmosphere. Novo Nordisk have used genetically modified Escherichia coli to produce melatonin. In 2022, the discovery of serotonin N-acetyltransferase (SNAT) —
2520-512: Is recommended. This includes blocking out noise and light during sleep, maintaining a regular, predictable sleep routine, avoiding heavy foods and alcohol before sleep, and sleeping in a comfortable, cool environment. Alcohol consumption, caffeine consumption and heavy meals in the few hours before sleep can worsen shift work sleep disorders. Exercise in the three hours before sleep can make it difficult to fall asleep. Free online training programs are available to educate workers and managers about
2610-417: Is the hydroxylation of L -tryptophan's indole ring by the enzyme tryptophan hydroxylase , resulting in the formation of 5-hydroxytryptophan (5-HTP). Subsequently, 5-HTP undergoes decarboxylation , facilitated by pyridoxal phosphate and the enzyme 5-hydroxytryptophan decarboxylase , yielding serotonin . Serotonin, an essential neurotransmitter , is further converted into N -acetylserotonin by
2700-472: Is used both as a prescription medication and an over-the-counter dietary supplement for the management of sleep disorders , including insomnia and various circadian rhythm sleep disorders such as delayed sleep phase disorder , jet lag disorder , and shift work sleep disorder . In addition to melatonin, a range of synthetic melatonin receptor agonists , namely ramelteon , tasimelteon , and agomelatine , are used in medicine. A study published by
2790-636: The Journal of the American Chemical Society , Lerner and his colleagues proposed the name melatonin, derived from the Greek words melas , meaning 'black' or 'dark', and tonos , meaning 'labour', 'colour' or 'suppress'. This naming convention follows that of serotonin , another agent affecting skin color, discovered in 1948 as a modulator of vascular tone , which influenced its name based on its serum vasoconstrictor effect. Melatonin
Swing Shift - Misplaced Pages Continue
2880-1054: The Chernobyl disaster . The Alaska Oil Spill Commission's final report on the Exxon Valdez oil spill disaster found that it was "conceivable" that excessive work hours contributed to crew fatigue, which in turn contributed to the vessel's running aground . The practices and policies put in place by managers of round-the-clock or 24/7 operations can significantly influence shift worker alertness (and hence safety) and performance. Air traffic controllers typically work an 8-hour day, 5 days per week. Research has shown that when controllers remain "in position" for more than two hours, even at low traffic levels, performance can deteriorate rapidly, so they are typically placed "in position" for 30-minute intervals (with 30 minutes between intervals). These practices and policies can include selecting an appropriate shift schedule or rota and using an employee scheduling software to maintain it, setting
2970-492: The G-protein coupled receptors (GPCRs) family, specifically the G i/o alpha subunit GPCRs, although melatonin receptor 1 also exhibits coupling with G q alpha subunit . Furthermore, melatonin functions as a high-capacity antioxidant , or free radical scavenger, within mitochondria , playing a dual role in combating cellular oxidative stress . First, it directly neutralizes free radicals , and second, it promotes
3060-662: The Journal of the American Medical Association (JAMA) in April 2023 found that only 12% of the 30 melatonin product preparations analyzed had melatonin quantities within ±10% of the amounts specified on their labels. Some supplements were found to contain up to 347% of the declared melatonin content. In Europe, melatonin is classified as an active pharmaceutical ingredient , highlighting the regulatory oversight of its use and distribution. Conversely, as of 2022 ,
3150-399: The anterior pituitary gland, especially in mammals that have a breeding season when daylight hours are long. The reproduction of long-day breeders is repressed by melatonin and the reproduction of short-day breeders is stimulated by melatonin. In sheep, melatonin administration has also shown antioxidant and immune-modulatory regime in prenatally stressed offspring helping them survive
3240-459: The gene expression of essential antioxidant enzymes, such as superoxide dismutase , glutathione peroxidase , glutathione reductase , and catalase . This increase in antioxidant enzyme expression is mediated through signal transduction pathways activated by the binding of melatonin to its receptors. Through these mechanisms, melatonin protects the cell against oxidative stress in two ways, and plays other roles in human health than only regulating
3330-606: The immune system is recognized, yet the specifics of these interactions remain inadequately defined. An anti-inflammatory effect appears to be the most significant. The efficacy of melatonin in disease treatment has been the subject of limited trials, with most available data deriving from small-scale, preliminary studies. It is posited that any beneficial immunological impact is attributable to melatonin's action on high-affinity receptors (MT1 and MT2), which are present on immunocompetent cells. Preclinical investigations suggest that melatonin may augment cytokine production and promote
3420-425: The mitochondrial matrix is significantly higher than that found in the blood plasma , emphasizing its role not only in direct free radical scavenging but also in modulating the expression of antioxidant enzymes and maintaining mitochondrial integrity. This multifaceted role shows the physiological significance of melatonin as a mitochondrial antioxidant, a notion supported by numerous scholars. Furthermore,
3510-411: The suprachiasmatic nuclei from retinal photosensitive ganglion cells of the eyes rather than the melatonin signal (as was once postulated). Known as "the hormone of darkness", the onset of melatonin at dusk promotes activity in nocturnal (night-active) animals and sleep in diurnal ones including humans. In humans, ~30 μg of melatonin is produced daily and 80% of the total amount is produced in
3600-473: The 11 hours of daily rest). The EU directive also limits night work involving "special hazards or heavy physical or mental strain" to an average of eight hours in any 24-hour period. The EU directive allows for limited derogations from the regulation, and special provisions allow longer working hours for transportation and offshore workers, fishing vessel workers, and doctors in training (see also medical resident work hours ). For fewer operational errors,
3690-493: The 20th century emitted relatively low levels of blue light. It has been found that light containing only wavelengths greater than 530 nm does not suppress melatonin under bright-light conditions. The use of glasses that block blue light in the hours preceding bedtime can mitigate melatonin suppression. Additionally, wearing blue-blocking goggles during the last hours before bedtime is recommended for individuals needing to adjust to an earlier bedtime since melatonin facilitates
Swing Shift - Misplaced Pages Continue
3780-627: The FAA goal calls for Flight Controllers to be on duty for 5 to 6 hours per shift, with the remaining shift time devoted to meals and breaks. For aircraft pilots, the actual time at the controls (flight time) is limited to 8 or 9 hours, depending on the time of day. Fatigue due to shift work has contributed to several industrial disasters, including the Three Mile Island accident , the Space Shuttle Challenger disaster and
3870-523: The Occupational Health Supplement , 27% of all U.S. workers in 2015 worked an alternative shift (not a regular day shift) and 7% frequently worked a night shift. Prevalence rates were higher for workers aged 18–29 compared to other ages. Those with an education level beyond high school had a lower prevalence rate of alternative shifts compared to workers with less education. Among all occupations, protective service occupations had
3960-468: The United States was considering the inclusion of melatonin in pharmacy compounding practices. A preceding study from 2022 concluded that consuming unregulated melatonin products can expose individuals, including children, to melatonin quantities ranging from 40 to 130 times higher than the recommended levels when products are used 'as directed'. Anecdotal reports and formal research studies over
4050-445: The action of serotonin N -acetyltransferase , utilizing acetyl-CoA . The final step in the pathway involves the methylation of N -acetylserotonin 's hydroxyl group by hydroxyindole O -methyltransferase , with S -adenosyl methionine as the methyl donor, to produce melatonin. In bacteria , protists , fungi , and plants, the synthesis of melatonin also involves tryptophan as an intermediate but originates indirectly from
4140-407: The activation of melatonin receptors and its role as an antioxidant . In plants and bacteria, melatonin primarily serves as a defense mechanism against oxidative stress , indicating its evolutionary significance. The mitochondria , key organelles within cells, are the main producers of antioxidant melatonin, underscoring the molecule's "ancient origins" and its fundamental role in protecting
4230-442: The amine derived from tryptophan restores the aromaticity of the pyridine ring , leading to the production of 5-hydroxytryptamine and PLP. Serotonin N -acetyltransferase, with histidine residue His122, is hypothesized to deprotonate the primary amine of 5-hydroxytryptamine. This deprotonation allows the lone pair on the amine to attack acetyl-CoA, forming a tetrahedral intermediate . The thiol from coenzyme A then acts as
4320-513: The application of melatonin significantly mitigates the harmful effects of salinity. Foliar application increases the number of leaves, their surface area, increases fresh weight and the content of chlorophyll a and chlorophyll b, and the content of carotenoids compared to plants not treated with melatonin. Fungal disease resistance is another role. Added melatonin increases resistance in Malus prunifolia against Diplocarpon mali . Also acts as
4410-491: The blood level of melatonin above daytime baseline values. Although a role for melatonin as a plant hormone has not been clearly established, its involvement in processes such as growth and photosynthesis is well established. Only limited evidence of endogenous circadian rhythms in melatonin levels has been demonstrated in some plant species and no membrane-bound receptors analogous to those known in animals have been described. Rather, melatonin performs important roles in plants as
4500-413: The circadian cycle. Artificial lighting may additionally contribute to disturbed homeostasis . Shift work may also increase a person's risk of smoking. The health consequences of shift work may depend on chronotype , that is, being a day person or a night person , and what shift a worker is assigned to. When individual chronotype is opposite of shift timing (day person working night shift), there
4590-426: The crucial first days of their lives. During the night, melatonin regulates leptin , lowering its levels. Cetaceans have lost all the genes for melatonin synthesis as well as those for melatonin receptors. This is thought to be related to their unihemispheric sleep pattern (one brain hemisphere at a time). Similar trends have been found in sirenians . Until its identification in plants in 1987, melatonin
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#17328010296704680-597: The day shift, whereas 6-day shift provided better sleep quality compared to the 21-day shift. Shift work has been shown to negatively affect workers, and has been classified as a specific disorder (shift work sleep disorder). Circadian disruption by working at night causes symptoms like excessive sleepiness at work and sleep disturbances. Shift work sleep disorder also creates a greater risk for human error at work. Shift work disrupts cognitive ability and flexibility and impairs attention, motivation, decision making , speech , vigilance , and overall performance. To mitigate
4770-588: The earliest cells from reactive oxygen species . In addition to its endogenous functions as a hormone and antioxidant, melatonin is also administered exogenously as a dietary supplement and medication . It is utilized in the treatment of sleep disorders , including insomnia and various circadian rhythm sleep disorders . In humans, melatonin primarily acts as a potent full agonist of two types of melatonin receptors : melatonin receptor 1 , with picomolar binding affinity , and melatonin receptor 2 , with nanomolar binding affinity. Both receptors are part of
4860-474: The expansion of T cells , thereby potentially mitigating acquired immunodeficiencies . Melatonin's potential to regulate weight gain is posited to involve its inhibitory effect on leptin , a hormone that serves as a long-term indicator of the body's energy status. Leptin is important for regulating energy balance and body weight by signaling satiety and reducing food intake. Melatonin, by modulating leptin's actions outside of waking hours, may contribute to
4950-605: The field of meteorology , such as the National Weather Service and private forecasting companies, also use shift work, as constant monitoring of the weather is necessary. Much of the Internet services and telecommunication industry relies on shift work to maintain worldwide operations and uptime . Service industries now increasingly operate on some shift system; for example a restaurant or convenience store will normally be open on most days for much longer than
5040-527: The highest prevalence of working an alternative shift (54%). One of the ways in which working alternative shifts can impair health is through decreasing sleep opportunities. Among all workers, those who usually worked the night shift had a much higher prevalence of short sleep duration (44.0%, representing approximately 2.2 million night shift workers) than those who worked the day shift (28.8%, representing approximately 28.3 million day shift workers). An especially high prevalence of short sleep duration
5130-403: The hormone norepinephrine . Norepinephrine increases the concentration of intracellular cAMP via beta-adrenergic receptors , which in turn activates the cAMP-dependent protein kinase A (PKA). PKA then phosphorylates arylalkylamine N -acetyltransferase (AANAT), the penultimate enzyme in the melatonin synthesis pathway. When exposed to daylight, noradrenergic stimulation ceases, leading to
5220-489: The human costs are taken into account in a way which is hard for an algorithm to do as it would involve knowing the constraints and considerations of each individual shift worker and assigning a cost metric to each of those factors. Shift based hiring which is a recruitment concept that hires people for individual shifts, rather than hiring employees before scheduling them into shifts enables shift workers to indicate their preferences and availability for unfilled shifts through
5310-469: The hydrogen and the loss of one of the two hydrogen atoms on C5 would restore aromaticity , producing 5-hydroxy- L -tryptophan. The decarboxylation of 5-hydroxy- L -tryptophan to produce 5-hydroxytryptamine is then facilitated by a decarboxylase enzyme with pyridoxal phosphate (PLP) as a cofactor. PLP forms an imine with the amino acid derivative, facilitating the breaking of the carbon–carbon bond and release of carbon dioxide. The protonation of
5400-657: The immediate degradation of the protein by proteasomal proteolysis . The production of melatonin recommences in the evening, a phase known as the dim-light melatonin onset . Blue light, especially within the 460–480 nm range, inhibits the biosynthesis of melatonin, with the degree of suppression being directly proportional to the intensity and duration of light exposure. Historically, humans in temperate climates experienced limited exposure to blue daylight during winter months, primarily receiving light from sources that emitted predominantly yellow light, such as fires. The incandescent light bulbs used extensively throughout
5490-446: The interaction of melatonin with reactive oxygen and nitrogen species results in the formation of metabolites capable of reducing free radicals. These metabolites, including cyclic 3-hydroxymelatonin , N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), and N1-acetyl-5-methoxykynuramine (AMK), contribute to the broader antioxidative effects of melatonin through further redox reactions with free radicals. Melatonin's interaction with
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#17328010296705580-509: The labour-powers used up by day and those used up by night ... It is well known that this shift-system, this alternation of two sets of workers, predominated in the full-blooded springtime of the English cotton industry, and that at the present time it still flourishes, among other places, in the cotton-spinning factories of the Moscow gubernia . This 24-hour process of production exists today as
5670-526: The late 18th century. In 1867 Karl Marx wrote on the shift work system in Capital, Volume 1 : Capitalist production therefore drives, by its inherent nature, towards the appropriation of labour throughout the whole of the 24 hours in the day. But since it is physically impossible to exploit the same individual labour-power constantly, during the night as well as the day, capital has to overcome this physical obstacle. An alternation becomes necessary, between
5760-404: The length of shifts, managing overtime, increasing lighting levels, providing shift worker lifestyle training, retirement compensation based on salary in the last few years of employment (which can encourage excessive overtime among older workers who may be less able to obtain adequate sleep), or screening and hiring of new shift workers that assesses adaptability to a shift work schedule. Mandating
5850-426: The mental and physical stress of the job. Even though studies support 12-hour shifts are associated with increased occupational injuries and accident (higher rates with subsequent, successive shifts), a synthesis of evidence cites the importance of all factors when considering the safety of a shift. Shift work was once characteristic primarily of the manufacturing industry , where it has a clear effect of increasing
5940-479: The mid-1970s by Lynch and others demonstrated that melatonin production follows a circadian rhythm in human pineal glands. The first patent for the therapeutic use of melatonin as a low-dose sleep aid was awarded to Richard Wurtman at the Massachusetts Institute of Technology in 1995. The etymology of melatonin stems from its skin-lightening properties. As detailed in their publication in
6030-461: The molecule's ancient origins and its multifaceted roles across different domains of life . The mechanism of melatonin biosynthesis initiates with the hydroxylation of L -tryptophan, a process that requires the cofactor tetrahydrobiopterin (THB) to react with oxygen and the active site iron of tryptophan hydroxylase. Although the complete mechanism is not entirely understood, two main mechanisms have been proposed: The first mechanism involves
6120-635: The morning sleepers. There are four major determinants of cognitive performance and alertness in healthy shift-workers: circadian phase, sleep inertia , acute sleep deprivation and chronic sleep deficit . A cross-sectional study investigated the relationship between several sleep assessment criteria and different shift work schedules (3-day, 6-day, 9-day and 21-day shift) and a control group of day shift work in Korean firefighters. The results found that all shift work groups exhibited significant decreased total sleep time (TST) and decreased sleep efficiency in
6210-412: The negative effects of shift work on safety and health, many countries have enacted regulations on shift work. The European Union, in its directive 2003 /88/EC, has established a 48-hour limit on working time (including overtime ) per week; a minimum rest period of 11 consecutive hours per 24-hour period; and a minimum uninterrupted rest period of 24 hours of mandated rest per week (which is in addition to
6300-563: The negative health consequences of shift work. The United States National Institute for Occupational Safety and Health recommends employers avoid quick shift changes and any rotating shift schedules should rotate forward. Employers should also attempt to minimize the number of consecutive night shifts, long work shifts and overtime work. A poor work environment can exacerbate the strain of shift work. Adequate lighting, clean air, proper heat and air conditioning, and reduced noise can all make shift work more bearable for workers. Good sleep hygiene
6390-423: The night shift but efficiency increased in the rest day. Between-group analysis of the different shift work groups revealed that day shift sleep efficiency was significantly higher in the 6-day shift while night shift sleep efficiency was significantly lower in the 21-day shift in comparison to other shift groups ( p < 0.05). Overall, night shift sleep quality was worse in shift workers than those who just worked
6480-467: The night. The plasma maximum concentration of melatonin at night are 80–120 pg/mL and the concentrations during the day are between 10–20 pg/mL. Many animals and humans use the variation in duration of melatonin production each day as a seasonal clock. In animals including humans, the profile of melatonin synthesis and secretion is affected by the variable duration of night in summer as compared to winter. The change in duration of secretion thus serves as
6570-535: The onset of sleep. Melatonin is metabolized with an elimination half-life ranging from 20 to 50 minutes. The primary metabolic pathway transforms melatonin into 6-hydroxymelatonin , which is then conjugated with sulfate and excreted in urine as a waste product. It is primarily metabolized by the liver enzyme CYP1A2 and to a lesser extent by CYP1A1 , CYP2C19 , and CYP1B1 . For both research and clinical purposes, melatonin levels in humans can be determined through saliva or blood plasma analysis. Melatonin
6660-443: The overall effectiveness of each antioxidant. This compound has been found to be twice as efficacious as vitamin E , a known potent lipophilic antioxidant, in combating oxidative stress. The promotion of antioxidant enzyme expression, such as superoxide dismutase, glutathione peroxidase, glutathione reductase, and catalase, is mediated through melatonin receptor-triggered signal transduction pathways. Melatonin's concentration in
6750-406: The past few decades have established a link between melatonin supplementation and more vivid dreams . Melatonin's discovery is linked to the study of skin color changes in some amphibians and reptiles, a phenomenon initially observed through the administration of pineal gland extracts. In 1917, Carey Pratt McCord and Floyd P. Allen found that feeding extracts from the pineal glands of cows caused
6840-555: The penultimate, rate-limiting enzyme in the melatonin biosynthetic pathway — in the archaeon Thermoplasma volcanium firmly places melatonin biosynthesis in all three major domains of life, dating back to ~4 Gya. Naturally-occurring melatonin has been reported in foods including tart cherries to about 0.17–13.46 ng/g, bananas , plums , grapes , rice, cereals , herbs , olive oil , wine, and beer. The consumption of milk and sour cherries may improve sleep quality. When birds ingest melatonin-rich plant feed, such as rice,
6930-407: The restoration of leptin sensitivity during daytime, thereby counteracting leptin resistance . The biosynthesis of melatonin in animals involves a sequence of enzymatic reactions starting with L -tryptophan , which can be synthesized through the shikimate pathway from chorismate , found in plants, or obtained from protein catabolism . The initial step in the melatonin biosynthesis pathway
7020-516: The risk of other types of cancer. Working rotating shift work regularly during a two-year interval has been associated with a 9% increased the risk of early menopause compared to women who work no rotating shift work. The increased risk among rotating night shift workers was 25% among women predisposed to earlier menopause. Early menopause can lead to a host of other problems later in life. A recent study, found that women who worked rotating night shifts for more than six years, eleven percent experienced
7110-425: The risks associated with shift work and strategies they can use to prevent these. Algorithmic scheduling of shift work can lead to what has been colloquially termed as "clopening" where the shift-worker has to work the closing shift of one day and the opening shift of the next day back-to-back resulting in short rest periods between shifts and fatigue. Co-opting employees to fill the shift roster helps to ensure that
7200-474: The same species depending on the agronomic growing conditions, varying from picograms to several micrograms per gram. Notably high melatonin concentrations have been measured in popular beverages such as coffee, tea , wine , and beer , and crops including corn , rice , wheat , barley , and oats . In some common foods and beverages, including coffee and walnuts , the concentration of melatonin has been estimated or measured to be sufficiently high to raise
7290-478: The second mechanism proposes that oxygen interacts with the active site iron (II) first, forming iron (III) superoxide. This molecule could then react with THB to form an iron-peroxypterin intermediate. Following the formation of iron (IV) oxide from the iron-peroxypterin intermediate, this oxide selectively attacks a double bond to yield a carbocation at the C5 position of the indole ring. A subsequent 1,2-shift of
7380-586: The shikimate pathway. The pathway commences with D -erythrose 4-phosphate and phosphoenolpyruvate , and in photosynthetic cells, additionally involves carbon dioxide . While the subsequent biosynthetic reactions share similarities with those in animals, there are slight variations in the enzymes involved in the final stages. The hypothesis that melatonin synthesis occurs within mitochondria and chloroplasts suggests an evolutionary and functional significance of melatonin in cellular energy metabolism and defense mechanisms against oxidative stress, reflecting
7470-430: The skin of tadpoles to lighten by contracting the dark epidermal melanophores . The hormone melatonin was isolated in 1958 by Aaron B. Lerner , a dermatology professor, and his team at Yale University . Motivated by the possibility that a substance from the pineal gland could be beneficial in treating skin diseases , they extracted and identified melatonin from bovine pineal gland extracts. Subsequent research in
7560-404: The sleep-wake cycle. In mammals, melatonin is critical for the regulation of sleep–wake cycles, or circadian rhythms. The establishment of regular melatonin levels in human infants occurs around the third month after birth, with peak concentrations observed between midnight and 8:00 am. It has been documented that melatonin production diminishes as a person ages. Additionally, a shift in
7650-551: The timing of melatonin secretion is observed during adolescence, resulting in delayed sleep and wake times, increasing their risk for delayed sleep phase disorder during this period. The antioxidant properties of melatonin were first recognized in 1993. In vitro studies reveal that melatonin directly neutralizes various reactive oxygen species , including hydroxyl (OH•), superoxide (O2−•), and reactive nitrogen species such as nitric oxide (NO•). In plants, melatonin works synergistically with other antioxidants, enhancing
7740-406: The use that can be made of capital equipment and allows for up to three times the production compared to just a day shift. It contrasts with the use of overtime to increase production at the margin. Both approaches incur higher wage costs. Although 2nd-shift worker efficiency levels are typically 3–5% below 1st shift, and 3rd shift 4–6% below 2nd shift, the productivity level, i.e. cost per employee,
7830-582: Was associated with Stevens–Johnson syndrome . The European Medicines Agency withdrew the license for modafinil for shift workers for the European market because it judged that the benefits did not outweigh the adverse effects. Using caffeine and naps before night shifts can decrease sleepiness. Caffeine has also been shown to reduce errors made by shift workers. According to data from the National Health Interview Survey and
7920-499: Was for decades thought to be primarily an animal neurohormone. When melatonin was identified in coffee extracts in the 1970s, it was believed to be a byproduct of the extraction process. Subsequently, however, melatonin has been found in all plants that have been investigated. It is present in all the different parts of plants, including leaves, stems, roots, fruits, and seeds, in varying proportions. Melatonin concentrations differ not only among plant species, but also between varieties of
8010-431: Was reported by night shift workers in the transportation and warehousing (69.7%) and health-care and social assistance (52.3%) industries. It is estimated that 15–20% of workers in industrialized countries are employed in shift work. Shift work is common in the transportation sector as well. Some of the earliest instances appeared with the railroads, where freight trains have clear tracks to run on at night. Shift work
8100-400: Was thus aptly named to reflect its role in preventing the darkening of the skin, highlighting the intersection of biochemistry and linguistics in scientific discovery. In vertebrates, melatonin is produced in darkness, thus usually at night, by the pineal gland , a small endocrine gland located in the center of the brain but outside the blood–brain barrier . Light/dark information reaches
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