1
|
Jeong H, Chae CH, Lee JH, Chong HW. The relationship between shift work pattern and thyroid stimulating hormone in female workers. Ann Occup Environ Med 2023; 35:e14. [PMID: 37614333 PMCID: PMC10442579 DOI: 10.35371/aoem.2023.35.e14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/21/2023] [Accepted: 05/24/2023] [Indexed: 08/25/2023] Open
Abstract
Background Shift work is known to cause changes in the circadian rhythm of the human body and adversely affect not only physical health but also mental health. Some studies have demonstrated the correlation between shift work and thyroid stimulating hormone (TSH), a hormone that changes according to the diurnal rhythm, but few studies have reported the different TSH levels according to the shift work type. This study aimed to investigate changes in TSH according to the shift work type. Methods This study included 1,318 female workers who had a medical checkup at a university hospital in Changwon from 2015 to 2019. Shift work types were classified as non-shift work, regular 2 shifts, and irregular three shifts, and a TSH ≥ 4.2 mIU/L was defined as abnormal. A general linear model (GLM) was used to compare the TSH levels and the risk of subclinical hypothyroidism in each year, and a binary logistic analysis was performed using a generalized estimation equation (GEE) to compare the risk of subclinical hypothyroidism over the 5-year period. Results Of the 1,318 participants included in this study, 363, 711, and 244 were non-shift, two-shift, and irregular three-shift workers, respectively. In the GEE analysis, after adjusting for age, body mass index, smoking, and alcohol consumption, the odds ratios (ORs) were 1.81 (95% confidence interval [CI]: 1.15-2.86; p = 0.011) in 2 shifts and 2.02 (95% CI: 1.23-3.32; p = 0.006) in irregular three shifts, compared to non-shift. Conclusions Our results showed that shift work had a higher risk of subclinical hypothyroidism than non-shift work and that there was a significant difference in the risk of subclinical hypothyroidism according to the shift work type. These findings suggest that the shift work type can be considered in future thyroid function tests and evaluations.
Collapse
Affiliation(s)
- Hun Jeong
- Department of Occupational and Environmental Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
| | - Chang Ho Chae
- Department of Occupational and Environmental Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
| | - Jun Ho Lee
- Department of Occupational and Environmental Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
| | - Hyo Won Chong
- Department of Occupational and Environmental Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
| |
Collapse
|
2
|
Moon SH, Lee BJ, Kim SJ, Kim HC. Relationship between thyroid stimulating hormone and night shift work. Ann Occup Environ Med 2016; 28:53. [PMID: 27761265 PMCID: PMC5054581 DOI: 10.1186/s40557-016-0141-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/28/2016] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Night shift work has well-known adverse effects on health. However, few studies have investigated the relationship between thyroid diseases and night shift work. This study aimed to examine night shift workers and their changes in thyroid stimulating hormones (TSH) levels over time. METHODS Medical check-up data (2011-2015) were obtained from 967 female workers at a university hospital in Incheon, Korea. Data regarding TSH levels were extracted from the records, and 2015 was used as a reference point to determine night shift work status. The relationships between TSH levels and night shift work in each year were analyzed using the general linear model (GLM). The generalized estimating equation (GEE) was used to evaluate the repeated measurements over the 5-year period. RESULTS The GEE analysis revealed that from 2011 to 2015, night shift workers had TSH levels that were 0.303 mIU/L higher than the levels of non-night shift workers (95 % CI: 0.087-0.519 mIU/L, p = 0.006) after adjusting for age and department. When we used TSH levels of 4.5 ≥ mIU/L to identify subclinical hypothyroidism, night shift workers exhibited a 1.399 fold higher risk of subclinical hypothyroidism (95 % CI: 1.050-1.863, p = 0.022), compared to their non-night shift counterparts. CONCLUSIONS This result of this study suggests that night shift workers may have an increased risk of thyroid diseases, compared to non-night shift workers.
Collapse
Affiliation(s)
- So-Hyun Moon
- Department of Occupational and Environmental Medicine, Inha University Hospital, Incheon, Republic of Korea ; Department of Social and Preventive Medicine, School of Medicine, Inha University, Incheon, Republic of Korea
| | - Bum-Joon Lee
- Department of Occupational and Environmental Medicine, Inha University Hospital, Incheon, Republic of Korea
| | - Seong-Jin Kim
- Department of Occupational and Environmental Medicine, Inha University Hospital, Incheon, Republic of Korea ; Department of Social and Preventive Medicine, School of Medicine, Inha University, Incheon, Republic of Korea
| | - Hwan-Cheol Kim
- Department of Occupational and Environmental Medicine, Inha University Hospital, Incheon, Republic of Korea ; Department of Occupational and Environmental Medicine, School of Medicine, Inha University, Incheon, Republic of Korea
| |
Collapse
|
3
|
Bukowska A, Sobala W, Peplonska B. Rotating night shift work, sleep quality, selected lifestyle factors and prolactin concentration in nurses and midwives. Chronobiol Int 2014; 32:318-26. [PMID: 25364814 DOI: 10.3109/07420528.2014.975353] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The pattern of secretion of many hormones, including prolactin, is dependent on the circadian rhythm. Night shift work involves exposure to artificial light at night and sleep deficiency, which in turn can affect prolactin synthesis. The aim of this study was to evaluate a possible association between night shift work characteristics, sleep quality, lifestyle factors and prolactin concentration, using data from a cross-sectional study of nurses and midwives. A cross-sectional study was conducted among 327 nurses and midwives currently working on rotating night shifts, and 330 nurses and midwives working during the day (aged 40-60 years) (388 premenopausal and 269 postmenopausal). Information about night shift work characteristics, lifestyle, reproductive factors, sleep pattern and other covariates was collected through a face-to-face interview, and from a one-week work and sleep diary completed by the subjects. Weight and height were measured. Prolactin concentration was measured in the morning blood sample using the electrochemiluminesence immunoassay method. Associations were analyzed using linear regression models adjusted for important confounders. Analyses were carried out separately in pre- and postmenopausal women. None of the night shift work or sleep characteristics was significantly associated with prolactin concentration. Prolactin concentration was significantly (p < 0.05) inversely associated with smoking and time of blood sample collection. These results were consistent among both pre- and postmenopausal women. Nulliparity was significantly positively associated with prolactin among premenopausal women, but inversely among postmenopausal. Age was related to prolactin among postmenopausal women only. Our study indicates that rotating night shift work is not associated with prolactin concentration. Smoking, parity, time of blood collection and age among postmenopausal women were significant determinants of prolactin.
Collapse
Affiliation(s)
- Agnieszka Bukowska
- Department of Environmental Epidemiology, Nofer Institute of Occupational Medicine , Lodz , Poland
| | | | | |
Collapse
|
4
|
Morris CJ, Aeschbach D, Scheer FAJL. Circadian system, sleep and endocrinology. Mol Cell Endocrinol 2012; 349:91-104. [PMID: 21939733 PMCID: PMC3242827 DOI: 10.1016/j.mce.2011.09.003] [Citation(s) in RCA: 243] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 08/19/2011] [Accepted: 09/01/2011] [Indexed: 11/23/2022]
Abstract
Levels of numerous hormones vary across the day and night. Such fluctuations are not only attributable to changes in sleep/wakefulness and other behaviors but also to a circadian timing system governed by the suprachiasmatic nucleus of the hypothalamus. Sleep has a strong effect on levels of some hormones such as growth hormone but little effect on others which are more strongly regulated by the circadian timing system (e.g., melatonin). Whereas the exact mechanisms through which sleep affects circulating hormonal levels are poorly understood, more is known about how the circadian timing system influences the secretion of hormones. The suprachiasmatic nucleus exerts its influence on hormones via neuronal and humoral signals but it is now also apparent that peripheral tissues contain circadian clock proteins, similar to those in the suprachiasmatic nucleus, that are also involved in hormone regulation. Under normal circumstances, behaviors and the circadian timing system are synchronized with an optimal phase relationship and consequently hormonal systems are exquisitely regulated. However, many individuals (e.g., shift-workers) frequently and/or chronically undergo circadian misalignment by desynchronizing their sleep/wake and fasting/feeding cycle from the circadian timing system. Recent experiments indicate that circadian misalignment has an adverse effect on metabolic and hormonal factors such as circulating glucose and insulin. Further research is needed to determine the underlying mechanisms that cause the negative effects induced by circadian misalignment. Such research could aid the development of novel countermeasures for circadian misalignment.
Collapse
Affiliation(s)
- Christopher J Morris
- Division of Sleep Medicine, Brigham and Women's Hospital, Boston, MA, United States.
| | | | | |
Collapse
|
5
|
Circadian disruption leads to loss of homeostasis and disease. SLEEP DISORDERS 2012; 2011:964510. [PMID: 23471148 PMCID: PMC3581131 DOI: 10.1155/2011/964510] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 09/22/2011] [Accepted: 11/24/2011] [Indexed: 11/28/2022]
Abstract
The relevance of a synchronized temporal order for adaptation and homeostasis is discussed in this review. We present evidence suggesting that an altered temporal order between the biological clock and external temporal signals leads to disease. Evidence mainly based on a rodent model of “night work” using forced activity during the sleep phase suggests that altered activity and feeding schedules, out of phase from the light/dark cycle, may be the main cause for the loss of circadian synchrony and disease. It is proposed that by avoiding food intake during sleep hours the circadian misalignment and adverse consequences can be prevented. This review does not attempt to present a thorough revision of the literature, but instead it aims to highlight the association between circadian disruption and disease with special emphasis on the contribution of feeding schedules in circadian synchrony.
Collapse
|
6
|
Salgado-Delgado R, Tapia Osorio A, Saderi N, Escobar C. Disruption of circadian rhythms: a crucial factor in the etiology of depression. DEPRESSION RESEARCH AND TREATMENT 2011; 2011:839743. [PMID: 21845223 PMCID: PMC3154570 DOI: 10.1155/2011/839743] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 05/04/2011] [Accepted: 06/06/2011] [Indexed: 01/16/2023]
Abstract
Circadian factors might play a crucial role in the etiology of depression. It has been demonstrated that the disruption of circadian rhythms by lighting conditions and lifestyle predisposes individuals to a wide range of mood disorders, including impulsivity, mania and depression. Also, associated with depression, there is the impairment of circadian rhythmicity of behavioral, endocrine, and metabolic functions. Inspite of this close relationship between both processes, the complex relationship between the biological clock and the incidence of depressive symptoms is far from being understood. The efficiency and the timing of treatments based on chronotherapy (e.g., light treatment, sleep deprivation, and scheduled medication) indicate that the circadian system is an essential target in the therapy of depression. The aim of the present review is to analyze the biological and clinical data that link depression with the disruption of circadian rhythms, emphasizing the contribution of circadian desynchrony. Therefore, we examine the conditions that may lead to circadian disruption of physiology and behavior as described in depressive states, and, according to this approach, we discuss therapeutic strategies aimed at treating the circadian system and depression.
Collapse
Affiliation(s)
- Roberto Salgado-Delgado
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04306 México, DF, Mexico
| | - Araceli Tapia Osorio
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, 04306 México, DF, Mexico
| | - Nadia Saderi
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04306 México, DF, Mexico
| | - Carolina Escobar
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, 04306 México, DF, Mexico
| |
Collapse
|
7
|
Salgado-Delgado R, Angeles-Castellanos M, Buijs MR, Escobar C. Internal desynchronization in a model of night-work by forced activity in rats. Neuroscience 2008; 154:922-31. [PMID: 18472343 DOI: 10.1016/j.neuroscience.2008.03.066] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 02/19/2008] [Accepted: 03/25/2008] [Indexed: 11/28/2022]
Abstract
Individuals engaged in shift- or night-work show disturbed diurnal rhythms, out of phase with temporal signals associated to the light/dark (LD) cycle, resulting in internal desynchronization. The mechanisms underlying internal desynchrony have been mainly investigated in experimental animals with protocols that induce phase shifts of the LD cycle and thus modify the activity of the suprachiasmatic nucleus (SCN). In this study we developed an animal model of night-work in which the light-day cycle remained stable and rats were required to be active in a rotating wheel for 8 h daily during their sleeping phase (W-SP). This group was compared with rats that were working in the wheel during their activity phase (W-AP) and with undisturbed rats (C). We provide evidence that forced activity during the sleeping phase (W-SP group) alters not only activity, but also the temporal pattern of food intake. In consequence W-SP rats showed a loss of glucose rhythmicity and a reversed rhythm of triacylglycerols. In contrast W-AP rats did not show such changes and exhibited metabolic rhythms similar to those of the controls. The three groups exhibited the nocturnal corticosterone increase, in addition the W-SP and W-AP groups showed increase of plasma corticosterone associated with the start of the working session. Forced activity during the sleep phase did not modify SCN activity characterized by the temporal patterns of PER1 and PER2 proteins, which remained in phase with the LD cycle. These observations indicate that a working regimen during the sleeping period elicits internal desynchronization in which activity combined with feeding uncouples metabolic functions from the biological clock which remains fixed to the LD cycle. The present data suggest that in the night worker the combination of work and eating during working hours may be the cause of internal desynchronization.
Collapse
Affiliation(s)
- R Salgado-Delgado
- Departamento de Anatomía, Facultad de Medicina, Edificio "B" 4 Piso, Universidad Nacional Autónoma de México, México DF 04510, Mexico
| | | | | | | |
Collapse
|
8
|
Boivin DB, James FO. Light treatment and circadian adaptation to shift work. INDUSTRIAL HEALTH 2005; 43:34-48. [PMID: 15732302 DOI: 10.2486/indhealth.43.34] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Work at unconventional hours can have both long and short term consequences. Shift workers are often required to perform their duties at times that are not favoured by the body's endogenous clock, or circadian pacemaker. A typical night shift worker, for example, may report reductions in alertness and performance during shifts, or significant difficulty attaining sleep of recuperative value in the day, all the while being more likely to develop health complications. The study of circadian physiology has significantly contributed to our current ability to aid the shift worker deal with atypical schedules. We discuss the usefulness of light treatment as a countermeasure for maladaptation to atypical work schedules.
Collapse
Affiliation(s)
- Diane B Boivin
- Center for Study and Treatment of Circadian Rhythms, Douglas Hospital Research Center, affiliated to the Department of Psychiatry, McGill University, 6875 LaSalle Boulevard, room F-1127, Montreal, Quebec, H4H 1R3, Canada
| | | |
Collapse
|
9
|
Axelsson J, Akerstedt T, Kecklund G, Lindqvist A, Attefors R. Hormonal changes in satisfied and dissatisfied shift workers across a shift cycle. J Appl Physiol (1985) 2003; 95:2099-105. [PMID: 12882998 DOI: 10.1152/japplphysiol.00231.2003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although the literature claims that shift work is harmful, it overlooks the fact that that many shift workers are satisfied and stay healthy. There is little knowledge of the biological mechanisms mediating the differences in susceptibility. The present study compared satisfied and dissatisfied shift workers with respect to major anabolic and catabolic hormones. Forty-two male shift workers, with an extremely rapidly rotating shift schedule, were divided into two groups according to their ratings of satisfaction with their work hours. Morning blood samples were taken during the first and last morning shift in the shift cycle. Serum was analyzed with respect to testosterone, cortisol, and prolactin. Dissatisfied shift workers had lower morning testosterone than satisfied ones, but they did not significantly differ with respect to cortisol or prolactin. Low testosterone levels were, in addition, associated with a greater sleep need, disturbed sleep/wakefulness, and an increased need for recovery after the work period, the latter being the best predictor of testosterone levels. The only change across the shift cycle concerned a significant decrease of morning cortisol at the end of the shift cycle. High morning cortisol was related to having a morning personality and fewer sleep problems before the morning shift. Dissatisfaction with the shift system seems related to lower testosterone levels, which in turn are related to disturbed sleep/wakefulness and increased need for sleep and recovery. Furthermore, morning cortisol was reduced across a shift cycle. It is suggested that reduced testosterone levels may be part of a mechanism of shift work maladjustment.
Collapse
Affiliation(s)
- John Axelsson
- National Institute for Psychosocial Factors and Health, Stockholm, Sweden.
| | | | | | | | | |
Collapse
|
10
|
Cauter E, Turek FW. Roles of Sleep‐Wake and Dark‐Light Cycles in the Control of Endocrine, Metabolic, Cardiovascular, and Cognitive Function. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
11
|
|
12
|
Weibel L, Brandenberger G. Disturbances in hormonal profiles of night workers during their usual sleep and work times. J Biol Rhythms 1998; 13:202-8. [PMID: 9615284 DOI: 10.1177/074873098129000048] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In a previous study, the authors reported that the 24-h rhythms of pituitary and adrenal hormones--that is, thyrotropin (TSH), prolactin (PRL), growth hormone, and cortisol--adapted only partially in a group of permanent night workers. However, the real impact of circadian rhythm alterations on the health and well-being of subjects is still unclear. In this study, the authors focus on an ergonomic field and address questions of adaptation of these hormones during the usual day sleep time (0700-1500 h) and during the usual night work time (2200-0600 h) in permanent night workers. Eleven night workers, working a night schedule for at least 2 years, submitted to a high-frequency blood sampling procedure (10 min) and to electroencephalographic recordings during sleep. The endocrine profiles of night workers were compared to those of day-active subjects studied during their usual sleep-wake schedule. During usual day sleep, despite an adapted sleep structure, cortisol levels among night workers were abnormally enhanced, whereas the TSH decreased in comparison to the plateau observed among day-active subjects. During usual work time, some hormonal disturbances persisted, in particular concerning cortisol and PRL (two hormones known to reflect the level of activation). Among night workers, the work time was associated with the quiescent period of cortisol secretion normally occurring during the first hours of sleep, and with a transient PRL increase. These results revealed altered hormonal profiles during the sleep time of night workers that do not result in an altered sleep pattern. The nocturnal work time, which requires a high level physical and mental performance, is associated with some endocrine alterations reflecting an eventual phase of hypovigilance.
Collapse
Affiliation(s)
- L Weibel
- Laboratoire des Regulations Physiologiques et des Rythmes Biologiques chez l'Homme, Institut de Physiologie-Faculté de Médecine, Strasbourg
| | | |
Collapse
|