Survey about Sleepiness and Adaptation to Night- Shift Workers in Metallurgy Industry

Transcription

1 International Research Journal of Applied and Basic Sciences 2015 Available online at ISSN X / Vol, 9 (8): Science Explorer Publications Survey about Sleepiness and Adaptation to Night- Shift Workers in Metallurgy Industry Arash Akbarzadeh 1, Saber Moradi 2, Zohreh Yazdi 3, Tayeb Ramim 4, Mahsa Hami 5, Mohsen Karchani 6* 1. Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 2. MSc. Occupational Health Department, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 3. Metabolic Disease Research Center, Qazvin University of Medical Sciences, Qazvin, Iran. 4. Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences. 5. Master of Economic Development and Planning, University of Firoozkooh Branch, Islamic Azad University, Firoozkooh, Iran. 6. *PhD, Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, International Campus (TUMS.IC), Tehran, Iran. Corresponding author m-karchani@razi.tums.ac.ir ABSTRACT: Nowadays 24-hour performance is an inevitable part in many industries. Night work is a necessity for employees of a main part of labor force. Shift work is considered as working out of usual working hours (about 7 to 18).We used panel method. The studied society belongs to one of metallurgy industries. Ninety people were selected as samples. To collect sleepiness data from SSS (Stanford sleepiness scale) demographic information and questionnaire were utilized. The data was analyzed by SPSS software version Results show two identical groups of samples have largest degrees over four nights at 5:00 then at 3:00AM and 1:00 AM. The degree of sleepiness of second night was less than the first night. These findings can have important applications in increasing the safety and productivity of the workplace and the workers. Keywords: Work shift, sleepiness, adaptation, metallurgy. INTRODUCTION Many important perspectives of modern life including medical care, power generation, the military and law enforcement are operated by shift workers [ Nurminen T And et al (1998), Folkard S And et al (2005), Costa G And et al (2003), Folkard S And et al (2003), Knutsson A And et al (2003), Barger LK And et al (2005)].In developed countries, 15 to 30 percent of workforce operates beyond the standard daytime hours [ Beers 'I'M And et al (2000), Shields M And et al (2002), Rosekind MR And et al (2005) ].Shift work in its turn brings about many disadvantages specially sleep disorders. Night work leads to health problems like sleepiness and reduced performance and increases the number of road accidents [Akerstedt T And et al (1990), Kecklund G And et al (1993), Smith L And et al (1995), Dinges D.F And et al (1995) ]. These disadvantages are caused by circadian interference sleep during day and circadian suppression of the metabolism at night [Jewett E And et al (1991)]. Safety is a primary concern of both workers and their employers in most shift-working situations, particularly in nuclear power plants or chemical industries. Many factors can be involved in the term of lack of adjustment [Eastman C.I And et al (1994)]. Circadian rhythms are generated by a central pacemaker, the supra-schismatic nucleus (SCN) in the anterior hypothalamus, and are synchronized to the external environment [Moore RY And et al (1997), Moore RY (1997), Stephan FK And et al (1972)]. In a research on the excessive sleepiness amongst shift workers, permanent day and permanent night worker, it was concluded that shift work people were more involved to catastrophes caused by sleepiness, depression social and family problems than day workers. Also, people suffering from sleep disorders caused by shift working are more at risk of health and behavior problems. It was recommended that 10 percent of shift and

2 night workers have sleep disorders [Drake CL (2004)]. Another research about the association of sleep disorders and work injuries, were considerably at risk of work injuries caused by sleeping, night insomnia. It was resulted that night sleep disorders are associated with work injuries [Nakata A (2005)]. In a cross-sectional study survey on 4407 nurses, a questionnaire was responded to check the sleep patterns and previous job injuries. Outbreak of sleepiness was 26 percent amongst the nurses and there was a significant statistical association between sleepiness and work injury over previous 12 months [Suzuki K (2005)]. In this research we checked the pattern of sleepiness in work time amongst night workers and accordance with shift in a period of time. MATERIALS AND METHODS The present study tested the trend of sleepiness in night in 2 groups of shift workers and rate of adaptation to shift work after one night shift work would decrease sleepiness during the night shift. The participants worked as operators in a metal production plants in Iran. 93 shift workers volunteered. Subjects were asked to sign the consent form, confirming that they understood the goals, risks, and potential benefits of the study and their right to withdraw from the study at any time. University of Tehran Committee for Ethics approved the study. 3 workers had to be excluded in the final analysis because of personal reasons. The subjects work schedule was 2 days on morning shift (06.00 h to h), 2 days on evening shift (14.00 h to h), 2 days on night shift (22.00 h to 6.00 h), 2 days off work, and then the schedule was repeated [Karchani M(2011)]. The workers permitted four short breaks at night, average fifteen minutes, in four short breaks sleepiness was assessed using Stanford Sleepiness Scale. In one night 90 worker tested subjective alertness and then investigation of demographics characteristics and mean rate of sleepiness. For case and control methods worker divided in two same group's 2 consequence night group 1 tested then 2 consequence night group2. Data analysis All statistical analyses were performed using SPSS version 16.0 (SPSS Inc., Chicago, IL, USA). When the Kolmogorov-Smirnov test confirmed normality, parametric tests were carried out. Using the paired t-test, we compared sleepiness between two nights in two groups. RESULTS 90 participants out of 93 volunteered completed the study. The average breaks had a means length of 15+/-1 minute. The timing of breaks or their frequency did not significantly differ between 2groups. All of the participants were male aged between years. General Information Related to the People Tested in the Research is given in Tables (1) and (2). Table 1. Descriptives of demographic characteristics The first group Mean± S.D The second group Mean± S.D P-value Age 30.24± ± BMI 24.30± ± Years of shift work 4.75± ± Smoking rates 1.85± ± According to table (1) shows, there is no significant difference between the age averages, BMI, years of working and the level of smoking amongst both groups of workers attended in the research(p-value>0.05). Thus, with 99 percent of confidence interval there is similarity amongst the studied community. More individual information of both groups is shown in the table below: 1438

3 Table 2. Relative Abundance of Attended People in the Study Variable Group Subtype Count The relative abundance Single Marital status Married Single 9 20 Married Illiterate Lower than diploma Diploma Educational status Higher than diploma Lower than diploma Diploma Higher than diploma Non-smokers Smokers Smoking Non-smokers Smokers Thus, with 99 percent of confidence interval there is similarity amongst the studied community. Results of the Average of Sleepiness The results of the mean of sleepiness of people in 4 different times (23:00, 1:00, 3:00 and 5:00) are measured separately in two groups in the base night are shown in table 3: Table 3.The mean of sleepiness in 2 groups in base night (time) 11PM 1AM 3AM 5AM Group Group In table (3), a significant difference was detected between 2 groups. Chart 1.Shows the basic night (BASE-TIME) According to diagram 1, both of the groups have equal level of sleepiness and there is no significant statistical difference. In diagram (1), display that sleepiness score for 2 groups are same. In this sense we assume that: Time1= Night one of test of group one Time2= Night two of test of group one 1439

4 Time3=Night one of test of group two Time4= Night two of test of group two Diagrams of 2 and 3 comparing sleepiness score between two groups in 2 nights of shift work Test of first group Test of second group Chart 2.Sleepiness scores in first group Chart 3.Sleepiness scores in second group Diagrams of 2 and 3 display and compare the sleepiness score in 2 groups and 2 nights of shift work. Table 4. Comparison of rate of sleepiness Time 1- time 2 <0.001 Group 1 Group 2 Time 3-time 4 <0.001 In table (4), Sleepiness score at second night in 2 groups were significantly less than sleepiness score at first night (p<0.05). 1440

5 DISCUSSION AND CONCLUSION According to SSS completed at 23:00, 1:00, 3:00 and 5:00 AM hours, the increase in the amount of sleepiness peaks at 5:00 hours, followed by 3:00 hours. This increase in sleepiness was consistent over the 5 days of study. In this research, as tables 1 and 2 show, both these groups have no demographic differences and are identical. Diagram 1 also shows the identical selection of groups in the sense of sleepiness. Diagrams 1 to 5 show an increasing trend in the level of sleepiness since early hours to the end of work. Table 3 illustrates the maximum mean of the level of sleepiness over four nights of study in 5:00 and then 3:00 (The mean of sleepiness: 11:00 1:00 3:00 5:00) and this result is compatible with other studies and shows that the highest level of sleepiness during the night shift is at 2:00, 4:00 and 6:00 [Lowden A and et al (2004)]. This research shows that the level of sleepiness during the second night of study has a decrease in comparison with both the first night and this is consistent with the results of a similar research in Sweden in which it was resulted that by two 20-minute periods of bright light exposure during the night the level of sleepiness decreased significantly (measured by using KSS questionnaire) and second night whit bright light or dim light adaptation was happen [Lowden A and et al (2004)] and the baseline which can be considered as a result of adaptation to shift work due to exposure to bright light (BL). This decrease in sleepiness during consecutive nights is consistent with the results from other similar studies that have shown an increase in adaptation to night shift due to exposure to bright light during 5 consecutive nights of night shift work, which disappeared at the weekend [Lowden A and et al (2004)]. These landings can have important applications for increasing the safety and productivity of the workplace and workers. ACKNOWLEDGEMENTS The authors gratefully acknowledge the cooperation of the study participants and their managers. We thank the subject volunteers and subject involved in data collection REFERENCES Akerstedt T, Gillberg M Subjective and objective sleepiness in the active individual. Int j.neurosci, 1990, 52: Barger LK, Cade BE, Ayas NT Extended work shifts and the risk of motor vehicle crashes among interns. N Engl J Med.2005, 325: Beers 'I'M Flexible schedules and shift work: replacing the '9-to-5' workday?.mon Labor Rev.2000, Costa G Shift work and occupational medicine: an overview. Occup Med. 2003, 53: Dinges DF An overview of sleepiness and accidents. J Sleep Res. 1995, 4: Costa G. The impact of shift and night work on health. Appl. Ergonomics. 1995, 27: Drake CL.2004.Shift work sleep disorders : prevalence and consequences beyond that of symptomatic day workers.2004;27(8):9-11. Eastman CI, Stewart KT, Mahoney MP Dark goggles and bright light improve circadian rhythm adaptation to night- shift. Sleep 1994, 17: Folkard S, Lombardi DA, Tucker PT Shift work: safety, sleepiness and sleep. Ind Health 2005, 43: Folkard S. Tudker PT. Shift work, safety and productivity. Occup Med. 2003, 53: Jewett E, Kronauer RE, Czeiler CA Light - induced suppression of endogenous circadian amplitude in humans. Nature. 1991, 6: KARCHANI M, KAKOOEI H, YAZDI Z, ZARE M. Do bright light shock exposures during breaks reduce subjective sleepiness in night workers? Sleep Biol Rhythms 2011;9(2): Kecklund G, Akerstedt T Sleepiness in long distance truck driving: an ambulatory EEG study of night driving. Ergonomics. 1993, 36: Knutsson A Health disorders of shift workers. Occup Med. 2003, 53: Lowden A, Akerstedt T, Wibom R Suppression of sleepiness and melatonin by. Bright light exposure during breaks in night work. J Sleep Res.2004; 13: Moore RY, Eichler VB Loss of j circadian adrenal corticosterone rhythm following suprachiasmatic lesions in the rat Brain Res 1972; 42: Moore RY Circadian rhythms: basic neurobiology and clinical applications. Annu Rev Med 1997; 48: Nakata A Sleep related risk of occupational injuries in Japanese small and medium scale enterprises.2005;43(1): Nurminen T Shift work and reproductive health. Scan J Work Environment Health. 1998, 24: Rosekind MR Managing work schedules: an alertness and safety perspective. Principle and Practice of Sleep Medicine. 4 th ed P Shields M Shift.work and health. Health Rep. 2002, 13: Smith L, Folkard S, Poole C Light treatment for NASA shift workers. Chronabiol. Int. 1995, 12: Stephan FK, Zucker I Circadian rhythms in drinking behavior and loco motor activity of rats arc eliminated by hypothalamic lesions. Proc Natl Acad Sci USA 1972, 69: Suzuki K.2005.Daytime sleepiness, sleep habits and occupational accidents among hospital nurses.j Adv Nurse. 2005; 52(40):