Discussion
Human physiology is arranged to sleep at night and to be awake in the daytime. This can be evidenced by hormones released in the circadian rhythm. Among these hormones, melatonin is released during nighttime sleep, but not during daytime sleep. Sudden changes in melatonin release can produce a jet-lag-like condition, resulting in a disruption in human mental health and sleep rhythm. Similarly, the shift system that requires staying awake at night can affect sleep physiology and many other hormonal mechanisms. Studies have reported that the night-shift can be associated with a wide range of negative conditions, from decreased visual acuity, lack of attention and sleep disorders to psychiatric comorbidities.
There are many studies on psychiatric disorders associated with nighttime insomnia. These studies addressed problems such as impaired sleep physiology, decreased quality of life, depression and anxiety disorders. However, there is no study literature investigating the concentration and maintenance of attention in healthcare professionals in intensive care units and the risks that might otherwise arise for patients.
The necessity of providing uninterrupted health care services worldwide requires many healthcare professionals to work in the night-shift system. It would not be wrong to say that health problems associated with night-shifts can also be seen in healthcare workers.
As per their duties, healthcare professionals are responsible for carefully monitoring the vital signs of patients and correcting potential disorders. These disorders may be respiratory or cardiac problems that require immediate action. The timely recognition and correction of these situations is directly related to the ability of healthcare professionals to collect and maintain their attention.
Indeed, in a study on shift-working nurses, Zion et al.13 reported poorer results of cognitive function tests at 3am than at 7am, suggesting that the night-shift caused a disruption in cognitive functions during night hours. Our study also reported significantly poor results of the SCWI test in the night-shift compared to the day-shift. This study has shown that a more regular circadian rhythm, attention-enhancing activities (visit, patient relatives visit, patient care, etc.) and a higher concentration of people in the day-shift than at night-shift, may result in faster collection of the attention and increased ability to focus due to the greater number of stimuli. Lack of stimuli and deterioration of sleep rhythm may result in distraction and loss of vital data that may require immediate attention. This highlights the patient-related causes of high mortality in the night-shift, as well as factors associated with healthcare professionals. As a result, deaths due to health personnel are among the preventable causes of death.
Studies that prove a decrease in attention level in night-shift workers also draw attention to the cases of self-injury due to carelessness in healthcare workers. Niu et al.5 applied the D2 test to nurses working in 3 shifts (day-, evening-, and night-shift), and reported an increase in selective error rate and a decrease in attention level in the night-shift. In this study, there was a day-shift group including nurses working from 08.00 to 16.00 and a night-shift group including nurses working from 16.00 until 08.00 on the next day. Given the longer duration of the night-shift (16 hours), the longer duration of the night-shift (16 hours), it is suggested that the decrease in the attention level of workers in the night-shift may be due to longer periods of work and sleeplessness. The longer duration of the night-shift in this study shows the potential higher rate of poor results when compared to the working hours in the studies by Niu et al.5. SCWI test showed a significant deterioration in duration, error and correction scores in the night-shift group, which seems to be consistent with the data of the literature studies.
Apart from the reduction in the attention level, it is also scientifically possible to predict an increase in the level of fatigue among night-shift workers. The study by Thompson et al.14 can be considered as proof of this prediction. It was reported in this study that performance-based fatigue increased in those working in the night-shift compared to those in the day-shift. It should not be ignored that serious risks may arise for both the patient and the healthcare professionals in case of a decrease in the level of attention in addition to the increase in fatigue. It should be remembered that there may be errors in the regulation of treatments, as well as an increased risk of self-injury in healthcare workers. It can be argued that the risk of injury to patients or healthcare workers will be higher for the night-shift group in our study, given the longer duration of the night-shift in our study (16 hours) compared to the duration of the night-shift (12 hours) in the study by Thompson et al.14
The imbalance of melatonin levels are known to be involved in the etiology of depression15,16. A study of hormonal changes reported a decrease in melatonin levels and an increase in inflammatory markers in night-shift workers17,18. Depending on the imbalance of melatonin levels, a depressive mood becomes inevitable in the night-shift employees. In our study, a significant difference in the scores of Hamilton depression scale between the employees working in the night-shift and day-shift was found to be compatible with the literature. Although Gumenyuk et al.19reported a disturbance in sleep quality as well as distraction in night-time healthcare workers, there was no difference between the groups in our study in terms of the results of PUKI, a test that assesses sleep quality. The difference between the sleep quality scores of our study and the study by Gumenyuk et al.19can be attributed to differences in sample size. Gumenyuk et al. used a total of 28 subjects in two groups.
This study was planned based on the hypothesis that a decrease in attention levels may have a significant effect on patient mortality. Literature studies have reported higher mortality rates in nighttime and weekend shifts in patients hospitalized in intensive care units. Although the researchers have tried to attribute high mortality rates to factors such as diagnostic and interventional disruptions, there is an overlook of the high rate of factors that make it difficult to collect attention during the weekend and night-shifts. Attention levels can be negatively affected by factors such as lower concentration of people and longer shift times during weekend and night-shifts, which is believed to contribute to an increase in mortality rates. In addition, the lower number of employees in night and weekend shifts should not be overlooked. The excessive number of chief nurses, support staff, clinicians and intensive care physicians during the day-shift causes the distribution of the burden of patient care. However, we believe that the absence of support staff in the night-shift, the decrease in the frequency of intensive care visits by the physician working in multiple units, and the excess of the number of patients per nurse also contributes to the reduction of attention by increasing the workload.
This study revealed a significant decrease in the level of attention in the night-shift compared to the day-shift. We believe that it will be beneficial to shorten the shift times, to keep the number of patients per staff at international standards, to set active rest periods and to plan personnel and hours to reduce the lack of attention observed in the night shift.