Drowsiness trend in night workers and adaptation to night shift in hospital staff


Background: Nowadays, 24-h performance is an inevitable part in many industries and public services. 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 7–18). Objective: The aim of this study is drowsiness trend in night workers and adaptation to night shift in hospital staff. Materials and Methods: We used panel method. The studied society belongs to one of the hospitals in Iran. Ninety staffs were selected as samples. To collect sleepiness, data from Stanford Sleepiness Scale demographic information and questionnaire were utilized. The data were analyzed by SPSS software version 22. Results: Results show two identical groups of samples have largest degrees over four nights at 5:00 then at 3:00 AM and 1:00 AM. The degree of correspondence of second night was more than the first night. Conclusion: These landings can have important applications in increasing the safety and productivity of the workplace and the workers.

Keywords: Adaptation, hospital staff, sleepiness, work shift

How to cite this article:
Poursadeghiyan M, Amjad RN, Baneshi MM, Farrokhi M, Poursadeghian A, Rohani M, Hami M, Khammar A. Drowsiness trend in night workers and adaptation to night shift in hospital staff. Ann Trop Med Public Health 2017;10:989-92
How to cite this URL:
Poursadeghiyan M, Amjad RN, Baneshi MM, Farrokhi M, Poursadeghian A, Rohani M, Hami M, Khammar A. Drowsiness trend in night workers and adaptation to night shift in hospital staff. Ann Trop Med Public Health [serial online] 2017 [cited 2020 Nov 24];10:989-92. Available from: https://www.atmph.org/text.asp?2017/10/4/989/215879

Nowadays, shift workers are engaged in key sectors such as health care, power stations, and military and law enforcement.[1],[2],[3],[4],[5],[6] Currently, some human resources about 15%-30%, work more than standard daytime hours in developed countries.[7],[8],[9] Among these, sleeping sicknesses occurs as a common problem because of shift working. Interrupted sleeping in the daytime, impaired function and high rate of car crash are some of the complications of working at night.[10],[11],[12],[13] The circadian suppression of the metabolism during the night and also circadian interference sleep during the day are responsible for these health issues.[14] In the most of the shift work jobs, especially in nuclear power stations or chemical products factories, safety is an essential issue for workforce and employers. Failure to adjustment could be related to several indicators.[15] Factors, such as a central pacemaker and a supra-schismatic nucleus, in the anterior hypothalamus are involved to coordinate circadian rhythms with the external environment.[16],[17],[18]

The results of a study investigating severe drowsiness demonstrated that the fixed night-shift workers are at a higher risk of complications such as drowsiness, social anxiety, and family conflict compared to the fixed day-shift workers. In addition, shift work could lead to sleep problems in individuals, which in turn could expose them to health issues and behavioral disorders. The sleep problems have been found among 10% of workers at night shift.[19]

Investigation of relationship between work-related injuries and sleep problems in a study demonstrated that some sleep problems at night including insomnia have a positive association with such work-related injuries.[20] Sleepiness is main issue in road safety.[21],[22]

To find an association between the sleep pattern and history of work complications, a cross-sectional study using a questionnaire proved that 26% of 4407 nurses were suffering from sleepiness over the past 12 months, indicating significantly statistical relationship between work complications and drowsiness.[23]


The present study aimed to investigate the drowsiness patterns in employees working at night-shift work in a certain period.

Materials and Methods

The sleepiness process during night was evaluated among shift workers within two groups in this study. This level could be reduced after one night adapting to shift work. Study population included the labors in steel manufacturing facilities in Iran in which 93 shift workers voluntarily participated in the study by signing informed consent form. The advantageous, hazards, and purposes of the study were explained to them who had right to discontinue the study at any timed. This study was conducted with approval of the Ethics Committee of University of Social Welfare and Rehabilitation. At the final analysis, three workers out of the total participants were excluded due to personal problems. The repetitive work schedule of participants included 8 h day shift from 22:00 to 6:00 for 2 days, 2 days break, 8 h morning shift from 6:00 to 14:00 for 2 days and 8 h evening shift from 14:00 to 22:00 for 2 days. Four 15-min rests during the night were allowed to the workers in which Stanford Sleepiness Scale (SSS) was used to evaluate the sleepiness level during the breaks.[24],[25] The subjective alertness was examined among 90 workers in one night. Then, investigation of demographics’ characteristics and mean rate of sleepiness worker divided into two same group’s: 2 consequence night worker in Group 1 tested then 2 consequence night worker in Group 2 tested.[26]

Data analysis

We used SPSS 11.5 under Windows XP for statistical analysis SPSS r version 21.0 (SPSS Inc., Chicago, IL). 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.


Ninety participants out of 93 volunteered completed the study. The average breaks had a means length of 15 ± 1 min. The timing of breaks or their frequency did not significantly differ between 2 groups.

All of the participants were male aged between 30 and 36 years.

General information related to the people tested in the research is given in [Table 1] and [Table 2].

Table 1: Descriptive of demographic characteristics

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Table 2: Relative abundance of attended people in the study

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According to [Table 1], there is no significant difference between the age averages, body mass index, years of working, and the level of smoking among both groups of workers attended in the research (P = 0.05). Thus, with 99% confidence interval, there is similarity among the studied community. More individual information of both groups is shown in [Table 2].

Thus, with 99% confidence interval, there is similarity among the studied community.

Results of the Average of Sleepiness

The results of the mean of sleepiness of people in four different times (23:00, 1:00, 3:00, and 5:00) are measured separately in two groups in the base night as shown in [Table 3]:

Table 3: The mean of sleepiness in two Groups in base night (time)

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In [Table 3], a significant difference was detected between two groups.

According to [Figure 1], both of the groups have equal level of sleepiness and there is no significant statistical difference.

Figure 1: Shows the basic night (BASE-TIME)

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[Figure 1] displays that sleepiness score for two groups is same.

In this sense, we assume that:

  • Time 1 = Night one of test of group one
  • Time 2 = Night two of test of group one
  • Time 3 = Night one of test of group two
  • Time 4 = Night two of test of group two

[Figure 2] and [Figure 3] are comparing sleepiness score between two groups in two nights of shift work.

Figure 2: Sleepiness scores in the first group

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Figure 3: Sleepiness scores in the second group

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[Figure 2] and [Figure 3] display and compare the sleepiness score in two groups and two nights of shift work.

In [Table 4], sleepiness score at second night in two groups was significantly less than sleepiness score at first night (P < 0.05).

Table 4: Comparison of rate of sleepiness

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During the 5 days of study, the steady increase in the sleepiness level was seen at 5:00 h followed by 3:00 h based on the SSS performed at 23:00, 1:00, 3:00, and 5:00 am h. The two groups in this study were matched in terms of demographic features [Table 1] and [Table 2]. The same choice of groups in the sense of sleepiness is seen in [Figure 1].

The processes of increased sleepiness levels during the beginning until the work time are given in [Figure 1],[Figure 2],[Figure 3]. Furthermore, the results of max average of sleepiness level within the four nights of study at 5:00 then 3:00 am (the average of sleepiness: 11:00 ≤ 1:00 ≤ 3:00 ≤ 5:00) shown in [Table 3] are in line with the results of other researches, indicating the highest sleepiness level at the hours 2:00, 4:00, and 6:00 at the night shift.[24],[25],[27],[28]

Regarding the present results, the sleepiness level has been reduced at the second night of the study compared to the first night. A similar study using KSS questionnaire conducted in Sweden reported that the sleepiness level could be significantly reduced by inducing the 20 min of bright light at night and it was adapted by a dim or bright light at the second night [24],[25],[27] and the bright light exposure resulting adaptation to shift work could considered as baseline.

A study on reducing sleepiness showed that experiencing bright light for five consecutive nights could increase the adaption to night shift, confirming our results.[27]


This study shows that the sleepiness level has been reduced at the second night of the study compared to the first night. The performance and safety of workplaces and employees could be improved by utilizing these findings.


The authors gratefully acknowledge the cooperation of the study participants and their managers. We thank the subject volunteers and subject involved in data collection.

Financial support and sponsorship

This study was supported by grant No 9352 in University of Social Welfare & Rehabilitation Sciences.

Conflicts of interest

There are no conflicts of interest.

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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ATMPH.ATMPH_307_17


[Figure 1], [Figure 2], [Figure 3]


[Table 1], [Table 2], [Table 3], [Table 4]

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