Scientific Online Resource System

Conference Proceedings


Irina Cekova, Ralitsa Stoyanova, Evelina Marinova, Verislav Stanchev, Katya Vangelova


Night shift work and long working hours are associated with an increased risk of some chronic diseases like cardiovascular, endocrine, digestive diseases and others. The aim of the study was to follow the impact of night shift work and long working hours on health of Bulgarian physicians.
A cross-sectional anonymous survey, comprising 761 physicians of age 44.3±14.1 years, and including information on work place variables, working hours and shift system was carried. The health status questionnaire included a list of 13 groups of diseases diagnosed by a physician. Statistical analyses were carried out with SPSS.
63.7% of the physicians worked rotating shifts, mainly 12- hour shifts (49.7%) and 67.5% had a history of night work. Overtime and multiple work places were common, contributing to long working hours/week with 38.5% working 41–50 hours/week, 27.8% - 51–60 hours/week and 13.7% - >61 hours/week. Results showed that the highest rate of cardiovascular diseases was in ex night shift workers both for males (F=18.728, p<0.01) and for females (F=9.940, p<0.01). The rate of cardiovascular, endocrine, digestive diseases was the highest in physicians who worked 51-60 or >61 hours/week, except for the rate of cardiovascular diseases in female physicians, the highest in those working 20-40 hours/week. Work schedule was a predictor of cardiovascular diseases and mental disorders; history of night work was a predictor of digestive diseases.
Our data contribute to the evidence that night shift work and long working hours increase health risk.


physicians, night shift work, long working hours

Full Text


Morris CJ, Purvis TE, Hu K, Scheer FA. Circadian misalignment increases cardiovascular disease

risk factors in humans. Proc Natl Acad Sci U S A, 2016;113(10):E1402-11.

Vyas MV, Garg AX, Iansavichus AV, Costella J, Donner A, Langsand LE et al. Shift work and

vascular events: systematic review and meta-analysis. BMJ, 2012; 345:e4800.

Park S, Nam J, Lee JK, Oh SS, Kang HT, Koh SB. Association between night work and

cardiovascular diseases: analysis of the 3rd Korean working conditions survey. Ann Occup

Environ Med, 2015;27:15.

Vetter C, Devore EE, Wegrzyn LR, et al. Association Between Rotating Night Shift Work and Risk

of Coronary Heart Disease Among Women JAMA. 2016; 315(16):1726–1734.

Cekova I, Vangelova K. P-44 The association between night shift work and cardiovascular and

endocrine diseases in healthcare workers in Bulgaria. Occupational and Environmental Medicine

; 78: A65. DOI: 10.1136/OEM-2021-EPI.173

van Drongelen A, Boot CRL, Merkus SL, Smid T, van der Beek AJ. The effects of shift work on

body weight change - a systematic review of longitudinal studies. Scand J Work Environ Health.

; 37(4): 263–275.

Proper KI, van de Langenberg D, Rodenburg W, Vermeulen RCH, van der Beek AJ, van Steeg H et

al. The Relationship Between Shift Work and Metabolic Risk Factors: A Systematic Review of

Longitudinal Studies. Am J Prev Med. 2016; 50(5): e147–e157.

Anothaisintawee T, Reutrakul S,Van Cauter E,Thakkinstian A. Sleep disturbances compared to

traditional risk factors for diabetes development: Systematic review and meta-analysis. Sleep

Med Rev 2016; 30: 11–24.

Hansen A., Stayner L, Hansen J, Andersen JZ. Night shift work and incidence of diabetes in the

Danish Nurse Cohort. Occupational and Environmental Medicine 2016; 73(4):262-268.

Nagaya T., Yoshida H., Takahashi H., Kawai M. Markers of insulin resistance in day and shift

workers aged 30-59 years. Intern. Arch. Occup. Environ. Health 2002; 75: 562-568.

Knutsson A. Health disorders of shift workers. Occup. Med. 2003; 53:103-108.

Saberi HR, Moravveji AR. Gastrointestinal complaints in shift-working and day-working nurses

in Iran. J Circadian Rhythms. 2010; 8:9.

Kim EJ, Jung HS and Choi EH. Relationship of Shift Work to Gastrointestinal Disorders in

Hospital Nurses. Korean J Health Promot 2014; 14(4):172-179.

Knutsson A, Bøggild H. Gastrointestinal disorders among shift workers. Scand J Work Environ

Health 2010; 36(2): 85–95.

Moreno CRC, Marqueze EC, Sargent C, Wright KP, Ferguson SA and Tucker P. Working time

society consensus statements: evidence-based effects of shift work on physical and mental

health. Industrial Health 2019; 57:139-157.

Megdal SP, Kroenke CH, Laden F, Pukkala E, Schernhammer ES. Night work and breast cancer

risk: a systematic review and meta-analysis. Eur J Cancer. 2005; 41(13): 2023–2032.

Jia Y, Lu Y, Wu K, Lin Q, Shen W, Zhu M et al. Does night work increase the risk of breast cancer?

A systematic review and meta-analysis of epidemiological studies. Cancer Epidemiology 2013;

(3): 197–206.

Цекова Ир, Вангелова К. Риск от хормон-зависими ракови заболявания при сменна работа.

Безопасност и здраве при работа 2016; 2 (1): 21-31 (ISSN 2367-7171). Налично в

електронен вид на:

Wang X, Ji A, Zhu Y, Liang Z, Wu J, Li S, Meng S, Zheng X, Xie L. A meta-analysis including

dose-response relationship between night shift work and the risk of colorectal cancer.

Oncotarget, 2015; 6(28):25046-60.

Rao D, Yu H, Bai Y, Zheng X, Xie L. Does night shift work increase the risk of prostate cancer?

A systematic review and meta-analysis. Onco Targets Ther, 2015; 8, 2817–26.

Kleppa E, Sanne B, Tell GS. Working overtime is associated with anxiety and depression: the

Hordaland health study. Journal of Occupational and Environmental Medicine,2008; 50:658–

Afonso P, Fonseca M, Pires JF. Impact of working hours on sleep and mental health. Occup Med

(Lond). 2017;1;67(5):377-382.

Virtanen M, Ferrie JE, Gimeno D, et al. Long working hours and sleep disturbances: the Whitehall

II prospective cohort study. Sleep, 2009;32(6):737–745.

Sagherian K, Clinton ME, Huijer HAS and Geiger-Brown J. Fatigue, work schedules, and

perceived performance in bedside care nurses. Workplace Health & Safety, 2016; 65(7), 304–

Virtanen M, Kivimäki M. Long Working Hours and Risk of Cardiovascular Disease. Curr Cardiol

Rep, 2018;20(11):123.;

Kivimäki M, Jokela M, Nyberg ST, Singh-Manoux A, Fransson EI, Alfredsson L, et al. Long

working hours and risk of coronary heart disease and stroke: a systematic review and metaanalysis

of published and unpublished data for 603 838 individuals www. 2015;


Kobayashi, T., Suzuki, E., Takao, S. et al. Long working hours and metabolic syndrome among

Japanese men: a cross-sectional study. BMC Public Health, 2012;(12)395.

Kivimäki M, Virtanen M, Kawachi I, Nyberg ST, Alfredsson L, Batty D, et al. Long working hours,

socioeconomic status, and the risk of incident type 2 diabetes: a meta-analysis of published and

unpublished data from 222 120 individuals. Articles 2015; 3(1): P27- 34).

Цекова И. Характеристика на сменните режими на работа и риска за здравето в болничната

помощ. Дисертация, Национален център по обществено здраве и анализи, София, 2022;

Автореферат наличен на:


Vangelova K, Cekova I, Dimitrova I. Sleep and fatigue in hospital physicians in relation to shift

work. Ukrainian Journal of Occupational Health 2018; 56 (3): 16-21.

Silva KKM, De Martino MMF, de Oliveira Viana MC, Bezerra CMB, Miranda FAN. Relationship

between work shifts and quality of sleep of nurses: a descriptive study. Online Brazilian Journal

of Nursing 2017; 16 (1):57-63.

Batak T, Gvozdenović L, Bokan D and Bokan D.The impact of nurses’ shift work on the fatigue

level SEEHSJ 2013; 3(2):120-127.

Härmä M.Workhours in relation to work stress, recovery and health. Scand J Work Environ

Health 2006; 32 (6): 502-514.

Tuomi, K., Ilmarinen, J., Jahkola, A., Katajarinne, L. and Tulkki, A. Work Ability Index. 2nd

Edition, Finnish Institute of Occupational Health, Helsinki. 1998.

Минчева Л., Вангелова К. Работоспособност: Оценка чрез определяне на индекса на

работоспособността, София, 2008

Frost P, Kolstad HA, Bonde JP. Shift work and the risk of ischemic heart disease – a systematic

review of the epidemiologic evidence. Scand J Work Environ Health 2009; 35: 163-179.

Wang N, Sun Y, Zhang H,Wang B, Chen C. Long-term night shift work is associated with the risk

of atrial fibrillation and coronary heart disease. European Heart Journal, 2021; 42 (40):4180–

Gan Y, Yang C, Tong X, Sun H, Cong Y, Yin X, et al. Shift work and diabetes mellitus: a metaanalysis

of observational studies. Occup Environ Med. 2015; 72(1): 72–78.

Silva-Costa A, Rotenberg L, Nobre AA, Schmidt MI, Chor D, Griep RH (2015) Gender-specific

association between night-work exposure and type-2 diabetes: results from longitudinal study

of adult health, ELSA-Brasil. Scand J Work Environ Health 41, 569–78.

Kim EJ, Jung HS and Choi EH. Relationship of Shift Work to Gastrointestinal Disorders in

Hospital Nurses. Korean J Health Promot 2014; 14(4):172-179.

Saberi HR, Moravveji AR. Gastrointestinal complaints in shift-working and day-working nurses

in Iran. J Circadian Rhythms. 2010; 8:9.

WHO/ILO joint estimates of the work-related burden of disease and injury, 2000-2016: global

monitoring report: WHO and ILO, 2021. License: CC BY-NC-SA 3.0 IGO.


Font Size