Introduction
The autonomic nervous system coordinates bodily
functions to ensure homeostasis (cardiovascular and respiratory
control, thermal regulation, gastrointestinal motility, urinary and
bowel excretory functions, reproduction, and metabolic and
endocrine physiology) and adaptive responses to stress (1). Autonomic responses to psychological
stress induce activation of sympathetic nerves with inhibition of
the parasympathetic nervous system and adrenocortical hormone
release to the heart, leading to increased heart rate, cardiac
output and blood pressure (2).
Psychological factors contribute to physiological processes (such
as sweating, cardiovascular and gastrointestinal arousal) via the
autonomic nervous system (3). Stress
is a major contributor to psychosocial and physical pathological
conditions (4).
Nursing students experience academic demands, such
as tests, theoretical and practical coursework, research
activities, various aspects of professional practice, and contact
with health professionals and patients. Consequently, nursing
students face numerous types of stress (5). Thus, increased stress levels contribute
to physical and psychological distress in nursing students
(6–8).
There is a concern that the added demands of modern nursing
programs place the students under greater pressure due to competing
demands (9). Therefore, we
hypothesized that high-grade students faced greater stressors, and
consequently had abnormal functioning of the autonomic nervous
system.
The aim of the present study was to examine the
functioning of the autonomic nervous system in nursing students by
assessing active standing load using the autonomic reflex
orthostatic tolerance test that enables quantitative analysis of
dynamic autonomic nervous system function.
Materials and methods
Design and participants
There were 121 nursing students (22 first-, 35
second-, 23 third- and 41 fourth-year students) enrolled at the
Kyoto Prefectural University of Medicine (Kyoto, Japan). These data
are >70% of stable R-R intervals without noise. There were 3
(2.5%) males and 118 (97.5%) females, and the average age was
20.6±1.8 years (range, 18–33 years). The investigation was carried
out between October 1, 2014 and January 31, 2015.
Data collection and analysis
For measurements of the autonomic nervous system
functions, a heart rate variability analysis method was used
(10). Heart rate and autonomic
nervous activity were measured. Electrocardiogram measurements were
obtained in a sitting position for 2 min, in a standing position
for 2 min and in a resting position for 1 min for autonomic reflex
orthostatic tolerance test. Real-time analysis was performed using
heart rate variability analysis software by Crosswell Co., Inc.,
(Yokohama, Japan). The coefficient of variation of R-R intervals
(CVRR) obtained from electrocardiograms were divided into
high-frequency (HF) and low-frequency (LF) components by power
spectrum analysis to evaluate the autonomic nervous activity. The
HF component reflects parasympathetic nervous activity, while the
LF/HF reflects sympathetic nervous activity. Coefficient of
component variance for HF (CCVHF) reflects the parasympathetic
nervous index, and CVRR as the variability of overall autonomic
nervous system activity. ΔCVRR was used as the response of the
autonomic nervous system. ΔLF/HF was used as the sympathetic
nervous system function in the standing position. ΔCCVHF was used
as the parasympathetic nervous system function in the sitting
position. The differences between the groups of each parameter were
analyzed using the Wilcoxon/Kruskal-Wallis test. A two-tailed
P<0.05 was considered to indicate a statistically significant
difference.
Ethics consideration
The study received Ethics approval from the
Institutional Review Board of the Kyoto Prefectural University of
Medicine (notice no. of determination: ERB-E-76, 2014). The
students received an information sheet that explained the purpose
of the study and methods, and were provided with assurance that
participation was voluntary and that their personal information
would be kept confidential during and following the study.
Results
Resting and standing states
The results of every student year for resting state
are shown in Table I. The activity of
the autonomic nervous system (CVRR) of fourth-year students was
lower compared with first-year students (fourth-year students,
5.02±1.37; first-year students, 5.80±1.53; P=0.017). There was a
trend of the sympathetic nervous system activity (LF/HF) of
fourth-year students to be higher compared with other student years
(fourth-year students, 3.69±3.57; third-year students, 2.10±1.97;
P=0.08). The parasympathetic nervous system activity (CCVHF) of
fourth-year students was lower compared with third-year students
(fourth-year students, 2.23±0.85; third-year students, 2.73±0.89;
P=0.015). The results for every student years for the standing
state are shown in Table II. There
was a trend of ΔCVRR of fourth-year students to be higher compared
with other student years (fourth-year students, 3.35±2.09;
second-year students, 2.38±2.56; P=0.10). There was a trend of the
sympathetic nervous system response (ΔLF/HF) of fourth-year
students to be lower among the other student years.
 | Table I.Autonomic nervous system functions of
the resting state in different student nursing years. |
Table I.
Autonomic nervous system functions of
the resting state in different student nursing years.
| Variables | First year, n=22 | Second year,
n=35 | Third year, n=23 | Fourth year,
n=41 |
Wilcoxon/Kruskal-Wallis testing
result |
|---|
| CVRR |
5.80±1.53 |
5.50±1.55 |
5.68±1.75 |
5.02±1.37 | First vs. fourth;
P=0.017 |
| LF/HF |
2.97±2.34 |
2.80±2.44 |
2.10±1.97 |
3.69±3.57 | NS |
| CCVHF |
2.46±0.75 |
2.36±0.77 |
2.73±0.89 |
2.23±0.85 | Third vs. fourth;
P=0.015 |
| Heart rate |
73.72±9.50 |
70.82±8.90 |
72.70±11.42 |
73.18±8.98 | NS |
| Table II.Autonomic nervous system functions of
the standing state in different student nursing years. |
Table II.
Autonomic nervous system functions of
the standing state in different student nursing years.
| Variables | First year, n=22 | Second year,
n=35 | Third year, n=23 | Fourth year,
n=41 |
Wilcoxon/Kruskal-Wallis testing
result |
|---|
| ΔCVRR |
2.57±2.13 |
2.38±2.56 |
2.76±1.71 |
3.35±2.09 | NS |
| ΔLF/HF |
4.20±7.47 |
3.94±7.88 |
3.60±4.39 |
2.60±3.61 | NS |
| ΔCCVHF |
0.57±0.41 |
0.46±0.40 |
0.48±0.65 |
0.38±0.71 | NS |
| Heart rate |
7.55±4.27 |
7.47±4.43 |
7.48±3.45 |
8.03±4.53 | NS |
Autonomic nervous system
functions
The results of the autonomic nervous system
functions of the resting state comparing fourth-year students with
first- to third-year students is shown in Fig. 1. The activity of the autonomic nervous
system (CVRR) of fourth-year students was lower compared with
first- to third-year students (fourth-year students, 5.02±1.37;
first- to third-year students, 5.63±1.59; P=0.025). There was a
trend of the sympathetic nervous system activity (LF/HF) of
fourth-year students to be higher compared with first- to
third-year students (fourth-year students, 3.69±3.57; first- to
third-year students, 2.65±2.29; P=0.19). The parasympathetic
nervous system activity (CCVHF) of fourth-year students was lower
compared with first- to third-year students (fourth-year students,
2.23±0.85; first- to third-year students, 2.49±0.81; P=0.04). The
results of the autonomic nervous system function in the standing
state comparing fourth- to first- to third-year students is shown
in Fig. 2. There was a trend of the
ΔCVRR of the fourth-year students to be higher compared with first-
to third-year students (fourth-year students, 3.35±2.09; first- to
third-year students, 2.54±2.20; P=0.07). ΔLF/HF and ΔCCVHF were not
significant between fourth- and first- to third-year students.
Discussion
The present study showed that fourth-year student
autonomic nervous system activity in the resting state was low,
there was parasympathetic hypotension and there was a trend of the
sympathetic nervous system activity of fourth-year students to be
higher compared with first- to third-year students. In the standing
state, there was a trend of the autonomic nervous system activity
response of fourth-year students to be higher compared with first-
to third-year students. Autonomic responses to psychological stress
induced the activation of sympathetic nerves with inhibition of the
parasympathetic nervous system (2). In
the standing state, there were several cases in the fatigue state
with a higher autonomic nervous system activity response (data not
shown). The present results suggest that stress may influence
autonomic nervous activity in fourth-year nursing students.
Long sleep hours and a regular diet are considered
the backbone of a healthy student lifestyle. Sleep decreases
sympathetic nerve activity (2). From
our previous study (11) it was
revealed that fourth-year nursing students had longer studying
hours with less sleeping hours. Therefore, the clinical training
and study hours had an effect on the life rhythm of fourth-year
nursing students. Additionally, lifestyle is affected by stresses,
including clinical nursing practice and studying for a national
board examination.
The stress response is mediated by the stress
system, which is located in the central nervous system and
peripheral organs. The main stress system includes the hypothalamic
pituitary axis and the systemic sympathetic adrenomedullary systems
(4). Stress is a major contributor to
psychosocial and physical pathological conditions (4). Chronic stress can cause physical,
behavioral and/or neuropsychiatric manifestations, such as anxiety,
depression, executive and/or cognitive dysfunction, and sleep
disorders such as insomnia (4).
Increased levels of corticotrophin-releasing hormone and/or stress
system abnormalities have been reported in behavioral and
neuropsychiatric disorders, such as anxiety, depression and eating
disorders. Low corticotrophin-releasing hormone activity has also
been implicated in depression (4). All
these disorders are associated with dysfunction of the stress
system (4).
Studying stress among nursing students is important
as this condition is associated with academic performance, which
can influence the quality of care in their future professional
life. It is necessary to design effective prevention and
intervention strategies for mental health problems in nursing
students through stress management. Determining how stress occurs
among nursing students is an essential step in preventing and
reducing the progression of health problems to more severe states.
There is widespread agreement that preventing health problems is a
better strategy compared to treating them after they become
apparent (12,13). Interventions aimed at reducing the risk
of health problems by treating autonomic nervous system dysfunction
may produce better results, although guidance in effective stress
management may be essential.
The limitations of the present study were that it
included a relatively small number of participants and that the
context was confined to a particular geographic location. However,
the study offers certain valuable insights into the autonomic
nervous system dysfunction among nursing students.
In conclusion, the present study confirmed that the
activity of the autonomic nervous system in the resting state in
fourth-year nursing students was low, there was parasympathetic
hypotension and there was a trend of the sympathetic nervous system
activity of fourth-year students to be higher compared with first-
to third-year students. In the standing state, there was a trend of
the autonomic nervous system activity response of fourth-year
students to be higher compared with first- to third-year students.
By correcting stress in fourth-year nursing students, it may be
possible to prevent the development of health problems.
Acknowledgements
The authors express their sincere gratitude to the
participants in the study who generously provided their time and
trust. The authors would like to express their gratitude to Ms.
Chieko Fujii and Mr. Motoi Nagaya for their technical
assistance.
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