Understanding the process for developing sleep disorders among Japanese workers: a qualitative study

Abstract

Background: Sleep disorders have an enormous impact on occupational health and are counterproductive from an economic perspective. However, the processes of causing sleep disorders from psychosocial aspects have not yet been known. The purpose of this study was to describe how sleep disorders develop among workers with respect to different psychosocial conditions.
Methods: A conventional qualitative content analysis was conducted with a semi-structured interview among twenty-seven workers (14 males and 13 females) who were diagnosed with sleep disorders or had a self-reported history of sleep difficulties. Study participants were recruited from a specialized clinic and communities using snowball sampling. This paper adhered to the Standards for Reporting Qualitative Research (SRQR) checklist.
Results: The results showed that there were four steps involved in the sleep disorders development process. Firstly, participants with sleep disorders developed ‘early warning signs’ with 11 categories of triggers; secondly, ‘aggravating factors’ on top of these early warning signs; thirdly, workers tried to ‘cope with’ their sleep disorders in the ways they thought would be effective. Finally, when coping failed to improve the quality of sleep, it led to the onset of sleep disorders.
Conclusion: The development of sleep disorders and triggers of psychosocial factors were revealed. An occupational health nurse can bring these findings in practice for preventing worker’s sleep disorders.

Full text

Toyoshima et al, Health Promotion Perspectives, 2020, 11(1), x-x
doi: 10.34172/hpp.2021.xx
https://hpp.tbzmed.ac.ir
Understanding the process for developing sleep disorders among
Japanese workers: a qualitative study
Ayako Toyoshima
ID
, Michiko Moriyama
ID
, Hidehisa Yamashita, Md Moshiur Rahman*
ID
, KATM Ehsanul Huq
ID
, Yasmin
Jahan
ID
, Kana Kazawa
Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
© 2021 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (http://
creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original
work is properly cited.
Abstract
Background: Sleep disorders have an enormous impact on occupational health and are
counterproductive from an economic perspective. However, the processes of causing sleep
disorders from psychosocial aspects have not yet been known. The purpose of this study was
to describe how sleep disorders develop among workers with respect to different psychosocial
conditions.
Methods: A conventional qualitative content analysis was conducted with a semi-structured
interview among twenty-seven workers (14 males and 13 females) who were diagnosed with
sleep disorders or had a self-reported history of sleep difficulties. Study participants were
recruited from a specialized clinic and communities using snowball sampling. This paper
adhered to the Standards for Reporting Qualitative Research (SRQR) checklist.
Results: The results showed that there were four steps involved in the sleep disorders
development process. Firstly, participants with sleep disorders developed ‘early warning signs’
with 11 categories of triggers; secondly, ‘aggravating factors’ on top of these early warning
signs; thirdly, workers tried to ‘cope with’ their sleep disorders in the ways they thought would
be effective. Finally, when coping failed to improve the quality of sleep, it led to the onset of
sleep disorders.
Conclusion: The development of sleep disorders and triggers of psychosocial factors were
revealed. An occupational health nurse can bring these findings in practice for preventing
worker’s sleep disorders.
Article History:
Received: 14 xx. 2019
Accepted: 8 xx. 2019
ePublished: 28 xx. 2020
Keywords:
Sleep disorders, Workers,
Psychosocial factors,
Occupational health
*Corresponding Author:
Md Moshiur Rahman,
Email: moshiur@hiroshima-u.
ac.jp
ARTICLE INFO
Original Article
Introduction
The global prevalence of sleep disorders was recorded
from countries ranging from 1.6% to 56.0%.1 Sleep
disorders have been associated with reduced working
performance,2 negative physical and mental health
outcomes and increased incidence of adverse safety
outcomes.3 Among the Organization for Economic Co-
operation and Development (OECD) countries, economic
loss due to sleep disorders is estimated to be between 1.4
to 2.3% of the gross domestic product (GDP).4 For these
reasons, sleep disorders are considered as an important
issue in occupational health.
Several occupational factors are known to interfere
with sleep. Studies reported the main factors such as
shift work, rest-duration, loneliness, workplace violence,
psychosocial stress,5 poor discretionary power over their
own work hours,6 and harassment7 were altering the
quantity and quality of sleep and the consequences, and
suggested health promotion measures.5-7
In Japan, particularly long working hours,8 high
consumption of alcohol, and the shortest sleep time
among 10 countries have been reported the increase in
higher health risk of workers including sleep disorders.9
A cohort study among Japanese employees from various
occupations notified that there was an association
between workaholism and poor sleep quality in terms of
sleep latency and daytime dysfunction.10
Even though health professionals in occupational health
settings have highlighted the importance of providing
information about sleep,11,12 specific guidelines on how to
prevent sleep disorders among workers are yet to be fully
developed. A combination of various practices and habits
of sleep hygiene is essential to ensure the quality of a good
night’s sleep and full daytime attentiveness.13 Workp l ace -
based employees’ health interventions also suggested
yoga, physical activities and cognitive-behavioral therapy
for insomnia interventions.14 However, until now, sleep
hygiene is the major intervention at a workplace for the
management of sleep disorders.15
Moreover, we can easily understand that there are
several factors other than occupational environment
affecting sleep disorders such as personal issues of
TUOMS
PRESS
Table-g

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Health Promot Perspect, 2021, Volume 11, Issue 1
2
family and human relationships. Balancing childbearing,
housework, and caregiving along with work are known as
stressful situations worldwide.16 Japan is ranked as one of
the lowest countries in terms of home-task sharing.17
Occupational health nursing is responsible for the
prevention of diseases related to the work environment
and to promote employees’ health.18 It also can help
employees solve the problems affecting their sleep
disorders, when the distinctive physical, psychosocial,
and environmental situations are specified. In fact,
there has been no qualitative discussion on how sleep
disorders develop among workers. If different situations
under which workers suffering from sleep disorders were
described, it might help to establish strategic ways for
preventing these sleep disorders from developing in the
occupational health field. The processes of developing
sleep disorders from psycho-social aspects have not yet
been known. Therefore, it is necessary to figure out those
factors and timings of prevention. The purpose of this
study was to explore the process of developing the sleep
disorders among the Japanese workers and to identify
various factors behind these disorders.
Materials and Methods
Study design and study setting
Between September and December 2015, we carried out
a conventional qualitative content analysis with a semi-
structured interview to investigate sleep disorders among
the Japanese workers in Hiroshima city, Japan. This
study adhered to the Standards for Reporting Qualitative
Research (SRQR, Appendix 1).19 The present qualitative
study was designed to identify the important and
appropriate research questions focused on revealing the
who (Japanese workers), what (sleep disorders), why, and
how they developed sleep disorders, and receiving insights
from informants regarding an unclear phenomenon.
Participants and procedures
Participants were full-and part-time workers, self-
employed or employed by private/public organizations,
aged ≥20 years. The inclusion criteria for participants
were having a diagnosis and receiving treatment for sleep
disorders, or a self-reported history of sleep difficulties.
Students and the unemployed were excluded from this
st u dy.
Participants were recruited from a specialized hospital
outpatient clinic and communities. In the hospital, the
psychiatrist in charge of sleep disorders introduced the
participants to the first author [the principal researcher
(PR)] who was a nursing graduate student specialized
in occupational health. In the communities, a snowball
sampling method was used20 in which the PR found two
informants who met the inclusion criteria and asked them
to introduce other workers through their networks. The
PR conducted individual face-to-face in-depth and semi-
structured interviews lasting approximately 60 minutes,
and these were conducted either once or twice when
further information was needed. To maintain privacy, the
interviews were conducted in a clinic or in an independent
PR’s office. Researchers stopped recruiting participants
when all the different patterns of sleep disorders
among patients [reference related to the international
classification of sleep disorders-3 (ICSD-3)] and all causes
of their sleep difficulties were saturated.
A total of 27 participants (14 males and 13 females; age
between 20 to 60 years) were recruited from the hospital
and the communities. The pattern of sleep disorders
among the participants was explained in Table 1.
Data collection tool
Participants were asked to reflect on the experience of
their sleep disorders. They were asked to answer the
following questions: (1) How did you perceive your
physical and mental health when you began to have a
Table 1. Characteristics of participants
Age
category Gender Occupation/Job type Types of sleep disorders
40's Male Office work Insomnia
50's Male Office work Insomnia
40's Male Factory work Insomnia
60's Female Nurse (no shift work) Insomnia
60's Female Elementary school teacher Insomnia
40's Male Agriculture Insomnia
60's Female Delivery work Central hypersomnia
40's Male Office work Insomnia
60's Male Office work Parasomnias
40's Male Office work Insomnia
50's Male Technologist Insomnia, sleep apnea
syndrome
30's Female Office work Central hypersomnia
30's Female Nurse (no shift work) Insomnia
50's Female University faculty Insomnia
30's Female Nurse (no shift work) Insomnia, sleep related
movement disorders
60's Male Office work Insomnia
30's Female Nurse (no shift work) Insomnia, circadian
rhythm disorder
40's Male Office work Insomnia
40's Male Manager Insomnia
40's Female Nurse (no shift work) Insomnia, sleep apnea
syndrome
40's Female Professional Insomnia
30's Female Nurse (shift work) Insomnia
50's Male Technician Insomnia
20's Female Nurse (childcare leave) Insomnia
60's Female High school teacher Insomnia
60's Male Office work Sleep apnea syndrome
50's Male Medical technician (with
night shift)
Sleep apnea syndrome,
sleep related movement
disorders

Toyoshima et al
Health Promot Perspect, 2021, Volume 11, Issue 1 3
trouble in sleeping? (2) How was your social situation at
that time? (3) Did you have any subjective symptoms? If
your answer is ‘yes’, what were the symptoms and what
were they like? (4) Did your sleeping difficulties affect
your business? If your answer is ‘yes’, how did it affect your
business? If your answer is ‘no’, please tell us how you were
able to manage your business without being affected by
your sleep disorders. (5) Why and how did you cope with
sleeping difficulties?
Participants’ characteristics such as gender, age,
occupation, past medical history, and current medical
condition were also collected. A digital voice recorder was
used to record the interviews after obtaining consent from
the participants.
Data analysis
The principal researcher performed a conventional content
analysis for this study. (1) The contents of the interviews
were documented and used for analysis. The analysis
findings were extracted, and categorized responses related
to the sleep disorders development process, (2) the reasons
for developing or not developing a coping behavior, and
(3) assessed the impact of sleep disorders had on work.
We used ICSD-321 to categorize major sleep disorders
such as insomnia, sleep-related breathing disorders,
central disorders of hypersomnolence, circadian rhythm
sleep-wake disorders, parasomnias, sleep-related
movement disorders, and other sleep disorders. When
the participants in the community had no diagnosis by a
specialist, on the basis of the Algorithm for the Evaluation
of Chronic Insomnia,22 we evaluated the conditions of the
patients’ sleep disorders. We asked the participants about
their sleep-wake timing patterns, snoring, and restless
leg symptoms, etc., and categorized these patterns for the
purpose of our study.
Ensuring trustworthiness and credibility
All the data were carefully analyzed on the meaning of
the contents, were coded, and categorized by researchers
who specialize in occupational health, chronic care and
qualitative analysis. In addition, collaborators who were
psychiatric specialists and sleep experts at the hospital
confirmed the validity of the analysis contents. Data were
also checked by the research participants, and they were
requested to confirm the consistency and credibility of the
contents.
Results
Process of sleep disorders development
Participants were requested to state what they thought
triggered the development of their sleep disorders and
what they did to overcome it. Four steps were generated
for developing sleep disorders. First, they developed ‘early
warning signs’ before starting to experience sleeping
difficulties. Secondly, ‘aggravating factors’ were added to
these ‘early warning signs’. Thirdly, workers tried to ‘cope
with’ sleeping difficulties. Lastly, when the coping strategy
failed to resolve their sleep difficulties, this led to the onset
(‘impact on work’) of their sleep disorders. However, they
did not develop a sleep disorder when the coping strategy
was effective because it made them sleep well (Figure 1).
Early warning signs
The main category (phase) of ‘early warning signs’
was generated and consisted of 11 categories and 27
subcategories (Table 2).
Early warning signs, which were triggering factors,
consisted of physical, psychosocial, and environmental,
behavioral, and combined factors along with holding
excessive beliefs about sleep that the participants were
experiencing or had developed before they began
experiencing sleep deterioration or deprivation.
The categories include: (1) ‘Insufficient sleeping hours
due to work environment’ and (2) ‘Lack of support
resources’. Physical and environmental factors symbolize
work culture in Japan characterized by long-commuting
distance, long working hours, and the custom of drinking
alcohol after work, leading to a lack of sleep. A participant
mentioned, “Every day, I work until 1am or 2am. If I can go
back on the last train, I am lucky. It is the same for everybody.”
Another person explained, “On weekends, I have to attend
my children’s events and housework that cannot be done on
weekdays. My husband just orders me. My parents’ home is
far, I cannot ask for help.” Lack of support was often related
to a lack of workload management. At home, gender
beliefs regarding housework, and long working hours at
the company and side jobs, due to economic conditions
had an influence on this. (3) ‘Jet lag and social jet lag’
is physically produced circadian rhythm imbalance by
workers’ frequent overseas business trips, shiftwork, and
wide differences between workdays and off days sleeping
time.
(4) ‘Disease symptoms’ such as uncontrolled itchiness
and (5) ‘Pregnancy/Breast feeding’ as a physical factor that
deprived them of a good night’s sleep. (6) ‘Caregiving’ and
(7) ‘Ill family members’ were physical and psychological
factors that also disturbed sleep. A participant stated,
“My father-in-law hurt me by bad words. I struggle, should
I take care of him? It sticks my heart and cannot sleep.”
Another participant spoke, “After my father’s health got
worse, I was worried whether he was alive at night, so I
woke up and went to check on him many times. It lasted for
months.” Caregiving at home generates a physical burden
and can cause conflict with the carer. Negative emotions
such as anger and worry often disturb their sleep over a
Figure 1. Process of developing sleep disorders

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Table 2. Onset of early warning signs for sleep disorders
Category Subcategory Code
Insufficient sleeping hours
due to work environment
Workplace habits of working until midnight
Long hours labor
Working environment to work until midnight
Unable to finish work duty within working hours
Long commuting hours Commuting time reduces sleeping time
Workplace with habit of drinking and eating out
after work
Drinking and eating out after work leads to going home later
Workplace drinking party customs
Lack of support resources Poor surrounding support resources No one to help with the job and consult sleep difficulties in the workplace
No one to help with housework and childcare
Jet lag and social jet lag
Overseas business trip Using sleeping pills to adjust to the time difference when traveling abroad
Shift work or time difference work
Night work
Do not know how to adjust one’s biorhythms during night shift
Inconsistent waking time because the schedule depends on the workload
Sleeping on weekends Weekends used to catch up on sleep missed on weekdays
Delayed sleep-phase due to sleeping in
Disease symptoms Uncontrolled symptoms Uncontrollable symptoms such as itchiness by atopic dermatitis, pain, cough
due to asthma
Pregnancy/Breast feeding Breast feeding Children crying throughout the night
Breast feeding at night
Pregnancy Morning sickness
Caregiving
Physical and Mental fatigue
Worries about family members with dementia wandering around and often
need to go and find her/him
Frequent trips to the toilet during the night
Conflict with a carer A carer throws/shouts unpleasant words. Cannot allow it.
Beliefs about use of social resources Taking care of family member is family’s task. Cannot ask for help. Use of
social resources is not accepted.
Ill Family members
Prolonged anxiety and nervousness (tension) for
anticipating changes in family’s situation
Worried about whether the family is alive
Nervousness due to unstable family condition (take care of the family at
bedside, and so nervous)
Anticipatory grief Anxiety about living after family dies
Families conflict
Anger, inferiority complex for families Inferiority complex that a family business cannot be inherited
Loneliness in the home, suppression of anger
The pace of my life is disturbed by adjusting time
to fit in with the lives of others Always adjusted my time to family time
Personal conflict
Keeping complaints inside/unable to solve
problems directly
Too much stress at work/human relationships, but cannot tell anybody,
cannot ask for help/ cannot resolve the problem
Unfinished business Unfinished developmental tasks Unmarried / pregnancy age limit
Bad handling of emotions Cannot handle emotions well. Anger and complaints inside.
Misbelief about sleep
Excessive commitment to sleeping time Commitment to bedtime routine
Commitment to total sleeping hours
Obsession/misunderstanding about their sleep
pattern
Cannot sleep well since a child. I am a bad sleeper. It takes a long time for
me to fall asleep.
Wrong knowledge about sleep Once missed the chance to fall asleep, cannot sleep anymore.
Habits of behavior
Thinking in bed
Thinking deeply in bed
Reflecting on the day in bed and arranging tomorrow’s business. Also, deep
regrets about the day and cannot sleep.
Coping behavior to relief stress
Internet, smart phone in bed
Drinking alcohol before bedtime
Eating late at night and before bedtime
Exposure to information until just before bedtime Checking the latest information on the bed
Difference of sleep pressure peak and living
conditions
Allowing them to sleep when they most want to sleep (Sleep in daytime/ right
after coming home/ after dinner, so cannot sleep at night).

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Health Promot Perspect, 2021, Volume 11, Issue 1 5
long period of time. (8) ‘Family conflict’ and (9) ‘Personal
conflict’ were psychological factors displaying negative
feelings towards family member(s) and/or his/herself
and were difficult to control. A participant stated, “I was
always told to take over the family business, but I did not
have the qualification. I always suffered from an inferiority
complex.” Another participant mentioned, “My child came
back to my house with her children. Younger ones have their
own time. I got to sleep late at night too, but I have to wake
up first and wake everyone up.” We observed the feeling
of inferiority complex among family member(s), worries
concerning unfinished business, an uncontrollable time
schedule for family members and feeling of anger. The
presence of long-term personal conflict also deprived
them of sleep.
Stereotypes regarding sleeping time and false knowledge
of drowsiness were categorized as (10) ‘Misbeliefs about
sleep’. Some participants obsessively attached high
importance to their bedtime routine, i.e. “I am a person
who cannot sleep before 12 midnight.” “I need 7 hours sleep,
but when I couldn’t then I really get upset.” As a behavioral
factor, (11) ‘Habits of behavior’ were extracted. This
includes thinking about or checking the Internet in bed,
drinking alcohol before bed, sleeping during the daytime,
and so forth.
Nobody stated about their physical environment such as
noise, lightning, temperature, bed or mattress, which was
related to the exacerbation.
Aggravating factors
An aggravating factor is another main category generated
from the interviews. As early warning signs were not
resolved and persisted, several factors have been attributed
to as factors aggravating sleep conditions. From 19
subcategories, 8 categories were generated. They included
(1) ‘Accumulation of fatigue’ in which people continued to
sleep for short hours, a hyperactive condition continued,
and some reported a drop in their physical strength. (2)
‘Feeling of urgency’ comes from continuous intensive
work and upset them. (3) ‘Crisis of social survival’ is
when they felt fear of losing their position and caught up
in feelings of defeat amid the competitive environment
at work. (4) ‘Life events and loss’ included loss of family
members, someone close to the participant, familiar
workplace, work position, and meaning of work. (5)
‘Changes in work’ refers to changes in working shifts
and being unable to adjust to new tasks. (4) or (5) could
be a trigger itself, but in this intervention these factors
appeared after the warning signs. (6) ‘Guilt for absence’
refers to increased feeling of guilt because they needed to
be absent due to their physical condition. (7) ‘Aggravation
of physical condition’ is an aggravation of tachycardia;
these physical conditions made their concerns worse. (8)
‘Economical anxiety’ results from a combination of age,
single status (being unmarried), health conditions, and an
obsessive for survival, all escalating their anxiety.
The balance between physical ability and amount of
work became worse because of a decline in physical ability
and insufficient sleeping time to recover from fatigue. The
participants felt pressured in the workplace and at home
from deadlines or when responding to emergencies. These
feelings aggravated their sleeping difficulties.
They became worried that they would lose their job,
and they had an inferiority complex with colleagues or
worried that they might lose their role at the workplace
because of their low performance evaluation. This leads to
insomnia as they have difficulty adapting to the changes
in new context or different working hours. In particular,
bereavement and change of workplace make them more
vulnerable and cause grief as they feel loneliness and
separated from their family.
Coping strategies
The third main category generated from the interviews
is ‘coping strategies’. It consisted of 2 categories i.e. (1)
‘getting support for solving their problems’, which includes
support from private such as family and friends, and
official services such as harassment consultation, nursing
services, and medical support. (2) ‘Personal efforts for
self-care’, which includes taking sleep aid supplement,
relaxation, maintaining sleep hygiene behavior, and
lifestyle changes. Some participants did not ask for help
because of reluctance to visit a psychiatry clinic, taking
medication, fear of retaliation after appealing to public
services, and obsessive thoughts about mother/caregiver
and being unable to request for aid.
Impact on work
The fourth main category generated from the interviews
is ‘impact on work’ as a result of all processes. The
consequences of sleep disorders on work were categorized
into two; one was the ‘negative impact on work’, and the
other one was the ‘able to do routine work’ with no impact
on work. In the negative impact, participants reported
that insomnia symptoms such as declining concentration
or strong drowsiness had a negative impacted on
their business. On the other hand, some could do the
routine work despite having insomnia symptoms. They
felt they could do their job without making mistakes
or causing troubles when they did the routine work.
Sleep disorders other than insomnia and circadian rhythm
disorders
In this study, sleep apnea, central hypersomnia,
parasomnia, and sleep-related movement disorder
were found the different processes from insomnia and
circadian rhythm disorders. We did not observe any
early warning signs or aggravating factors. Awareness of
mental and physical disorders due to drowsiness during
the daytime was recognized but because of minimum
knowledge about these sleep disorders, nobody perceived
any threat or necessity to seek treatment. Therefore, the
factors that triggered them to take action were: when their
family brought these factors under their notice, or at their

Toyoshima et al
Health Promot Perspect, 2021, Volume 11, Issue 1
6
workplace, they were recommended to go for a medical
examination, and found out, when they were exhibiting
physical symptoms or diseases such as obesity, diabetes,
and depression. They responded that they did not know
whom they should consult, did not feel the necessity
to undergo examination or treatment, interruption of
medical treatment, and they could not lose weight in case
of obesity.
Discussion
This study aimed to find out the process of developing
sleep disorders and identified underlying factors and
its impact on work. We believe a holistic approach
is necessary with respect to occupational nursing
perspective, paying attention to not merely on working
environment and sleep hygiene, but also, emphasis on
psychosocial factors to intervene. Nursing is a medical
profession, and it is important to strengthen the services
and inter-professional co-operation in healthcare. This
study revealed that Japanese cultural practices of long-
working hours, drinking customs after the work, and
burden of housework reduce the total sleep duration
which influenced to initiate the early warning signs of
sleep disorders. Sleep patterns differ among countries
influenced by sociodemographic and cultural status.23 In
our study, we found that sleep disorders were related to
physical, psychosocial, environmental, behavioral, and
combined factors. Similar findings were observed that
sleep disorders increased with medical and psychological
comorbidities.24 Another study documented that sleep
disturbance has a significant association with physical,
psychosocial, and environmental factors.25 This study also
described the types of features as participants’ personal,
family and working environment can influence to develop
sleep disorders.
Sleep has a vital role on various body systems including
brain functions. Our results indicated that occupational
health services, like sleep hygiene education or personal
counseling might be effective for improving the quality of
workers’ sleep when they displayed some early warning
signs and aggravating factors. Many occupational factors
may interfere with sleep which may cause significantly
short and long-term effects on health and safety.26 In
Japan, occupational factors such as higher work demands,
longer working hours, shift work, etc. are individually
associated with sleep disturbance.27 Similarly, some
other Asian countries such as South Korea documented
that violence, discrimination, work-life imbalance,
job dissatisfaction, high work demands and intensity,
and job insecurity are the common responsible factors
for sleep disturbance.28 The current study identified
some responsible factors on how workers develop sleep
disorders like long working hours, caregiving practice,
housework, nurturing baby, jet lag, social jet lag, some
disease conditions (i.e. itching, pain), family or personal
conflict and behavioral habits. Several studies found that
jet travel and night work resulted in a huge change at the
time for sleep and wake, a large phase shift, producing
circadian misalignment between sleep, work, meals and
the internal circadian rhythms.29,30 The high job demands
and overtime are important factors for long working
hours that have been associated with sleep disturbances.27
However, long working hours and sleep complaints might
be partially accounted for behavioral correlates like a
higher level of Internet addiction, alcohol consumption
and activities tended to have poorer sleep quality.31
The negative psychological and physiological impacts
of inadequate sleep also have been well-documented,
including emotional incidents,32 and increased risks of
participating in hazardous behaviors (e.g., tobacco and/or
alcohol consumption, driving while under the influence
of insufficient sleep).33 Based on the aforementioned
discussion, studies recommended developing a policy for
scheduled naps and providing a quiet room for rest breaks
and naps can be a countermeasure to reduce fatigue,
which can provide benefits to the workers.34
In this study, we described categories of early warning
signs and aggravating factors and how workers develop
sleep disorders. Some aggravating factors such as
accumulation of fatigue, urgency, and feelings of guilt for
being absent from work due to chronic diseases were related
to work-life balance. The most common aggravating factor
was fatigue for workers, especially those who were doing
a shifting duty. Shifting duties of the workers reduced the
quality and quantity of sleep that negatively interrupted
their quality of life and health including social activities.35
This study indicates psychological stress due to caregiving
(taking care of ill family members) and housework without
surrounding supports can also cause fatigue. There are two
key contributors to develop fatigue, insufficient sleep and
disruptions in the normal sleep cycle cause to circadian
misalignment. Tanaka et al. reported that alterations
in the biological rhythm increased circadian biological
dysfunctions, such as energy metabolism, autonomic
activity, endocrine, and neurocognitive dysfunctions.36
It is well documented that chronic illness such as
cardiovascular disease, diabetes, rheumatoid diseases,
and respiratory disorders are associated with reduced
health-related work performance and poor quality of
working life after the disease onset.37,38 Similarly, lack of
quality sleep can negatively impact work performance,
attention to tasks, and decision-making factors that may
increase workload and work-related stress.39 In addition,
discrimination and prejudice at the workplace which have
been associated with emotional stress disproportionally
affect workers with chronic diseases.40 These results
suggest the need to promote proper working hours and the
need for workers to have time to refresh. These findings
also demonstrate the importance of a good balance
between the treatment of chronic diseases and working.
From the above discussion, it appears that individuals
would be benefited from those aggravating factors by a
multi-disciplinary approach that helping the integration
process that encompasses the physical, emotional,

Toyoshima et al
Health Promot Perspect, 2021, Volume 11, Issue 1 7
social, vocational, and existential work of chronic illness
adjustment. Moreover, rehabilitative programs, health
promotion programs and more involvement from health
professionals, particularly nurses, have been advocated
as potentially important services for adults with chronic
illness to learn to optimize life.41 Based on the above
results, addressing the causes of early warning signs and
aggravating factors, it may become possible to construct
a program to prevent the onset of sleep disorders for
employees who suffer in the occupational health field. In
occupational health settings, workers with sleep-related
support do not always require diagnosis at a medical
institution. It is necessary that a worker who has difficulty
in sleeping, regardless of the presence or absence of a
sleep disorder-related diagnosis, should be provided with
occupational support in order to prevent developing sleep
disorders.
Furthermore, we explained why participants were
unsuccessful with coping strategies before developing
sleep disorders. Some participants did their best given their
own situation and tried to improve their lives such as by
adapting to a new job or family environment. It confirmed
that non-pharmacologic management such as sleep
hygiene education, counseling, and introducing social
resources in occupational health would be helpful as an
effective coping strategy against sleep disorders. The highly
stressed workers may be more prone to sleep disturbance,
nightmares, daytime malfunction, and lack of rest due to
sleep deprivation. In this regard, appropriate stress coping
strategies can improve sleep disorders even in the most
highly stressed individuals.42 Effective coping styles that
involve actively engaging problems, positively interpreting
situations, and using humor lead to faster resolution of
difficulties and help maintaining the psychological health
of an individual during times of stress, thereby allowing a
greater sense of safety and security. Coping could be either
problem-focused (e.g., by employing problem solving and
time management strategies) or emotion-focused (e.g.,
through mindfulness, relaxation, and obtaining emotional
support from colleagues or friends).43 So, the appropriate
strategy should be implemented to reduce work stress and
sleeping disorders from four main coping strategies which
have been discussed elsewhere.44
Our findings revealed that workers with sleep disorders
are likely to have a negative impact of low performance at
work or be absent from work. This is in line with a previous
study corroborating that sleep disorders are costly health
problems and resulting in the high estimated costs to
society of leaving the most prevalent sleep disorders
untreated that would be incurred by providing effective
management.45
The study has several limitations. The participants
were recruited through a snowball sampling method in
the community, so selection bias is a concern. The study
participants were also selected from a single city in Japan
which can restrict the generalizability of the study. During
the data collection, some participants were asked to tell
the previous history related to their sleep disorders, so
recall bias is another concern.
Implications for occupational health nursing practice
In Japan, there is a major change in the labor force due to
increasing aged population. As a consequence, Japanese
occupational health nurses adopted dramatically in
recent years to handle new and changing risks among
workers.46 Recently, companies adopted a good work-life
environment such as short working hours for childbearing
women and stop caregiving for all workers. However, still
there are many issues to pay attention as an occupational
health nurse.
The findings of this study can be used for a program
to manage sleeping disorder for workers. We have
developed an educational program and booklet and
applied it to company workers, in which we listed all
factors generated from this study and added assessment
tools and instructions on how to deal with those factors
specifically. We also described the process of sleep
disorders development. In the booklet, we brought
attention to the early warning signs before the onset. As
an occupational health nurse, not only providing sleep
hygiene information, we can pay more attention to these
individuals and environmental factors and can facilitate
in case management and collaborate with companies to
deal with the work conditions. The educational program
and materials we developed based on this study could be
widely implemented nationally and internationally for
further evaluation by the occupational health nurses.
Conclusion
Among the study participants, nobody had the knowledge
about the category of sleep disorders. There are a certain
number of participants who had no understanding of their
sleep difficulties such as SAS and other sleep disorders.
They could not recognize, did not ask for supports, did not
follow coping strategies, and tried to deal with disorders
by themselves. Therefore, routine screening system to
evaluate workers’ sleep condition by using standard tools/
questionnaires, counseling and treatment are essential. It is
also important to know the types of sleep disorders which
allow accurate diagnosis, improved communication with a
sleep specialist, and standardization of management plan
to improve the quality of life. This study suggests a holistic
approach involving both workers and occupational health
nurses for the prevention and control of sleep disorders.
Acknowledgements
The authors would like to thank all participants who shared their
experiences and perceptions in this study.
Funding
This study is carried out with funding of the Grants-in-Aid
for Scientific Research Program (KAKENHI), Japan (No.
15H05078).

Toyoshima et al
Health Promot Perspect, 2021, Volume 11, Issue 1
8
Competing interests
The author(s) declared no potential conflicts of interest with
respect to the research, authorship, and/or publication of this
article.
Ethical approval
The study protocol and procedures were approved by the ethics
committee of Hiroshima University, Japan (E-80). Written
informed consent was obtained individually from all the
participants.
Authors’ contributions
AT and MM were responsible for the conception and design
of the study. AT involved in data collection. AT, MM, HY, and
KK worked on data analysis and interpretation. AT, EH and
YJ drafted the original manuscript. MM, HY, MMR and KK
critically revised and finalized the manuscript. All authors read
and approved the final manuscript.
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Appendix 1. Standards for Reporting Qualitative Research (SRQR)
O’Brien B.C., Harris, I.B., Beckman, T.J., Reed, D.A., & Cook, D.A. (2014). Standards for reporting qualitative research: a synthesis of recommendations.
Academic Medicine, 89(9), 1245-1251.
No. Topic Item
Title and abstract
☑S1 Title →Title page
Concise description of the nature and topic of the study identifying the study as qualitative or
indicating the approach (e.g., ethnography, grounded theory) or data collection methods (e.g.,
interview, focus group) is recommended
→We used a qualitative study and described in the title.
☑S2 Abstract→P1 & 2 Summary of key elements of the study using the abstract format of the intended publication; typically
includes objective, methods, results, and conclusions
Introduction
☑S3 Problem formulation →P3 & 4 Description and signicance of the problem/phenomenon studied; review of relevant theory and
empirical work; problem statement
☑S4 Purpose or research question→P4 Purpose of the study and specic objectives or questions
Methods
☑S5 Qualitative approach and research
paradigm→P4
Qualitative approach (e.g., ethnography, grounded theory, case study, phenomenology, narrative
research) and guiding theory if appropriate; identifying the research paradigm (e.g., positivist,
constructivist/interpretivist) is also recommended
☑S6 Researcher characteristics and reexivity
→P5
Researchers’ characteristics that may inuence the research, including personal attributes,
qualications/experience, relationship with participants, assumptions, or presuppositions; potential
or actual interaction between researchers’ characteristics and the research questions, approach,
methods, results, or transferability
☑S7 Context →P4 & 5 Setting/site and salient contextual factors; rationalea
☑S8 Sampling strategy →P5 How and why research participants, documents, or events were selected; criteria for deciding when
no further sampling was necessary (e.g., sampling saturation); rationalea
☑S9 Ethical issues pertaining to human subjects
→P22
Documentation of approval by an appropriate ethics review board and participant consent, or
explanation for lack thereof; other condentiality and data security issues
☑S10 Data collection methods →P5 & 6
Types of data collected; details of data collection procedures including (as appropriate) start and
stop dates of data collection and analysis, iterative process, triangulation of sources/methods, and
modication of procedures in response to evolving study ndings; rationalea
☑S11 Data collection instruments and
technologies →P5 & 6
Description of instruments (e.g., interview guides, questionnaires) and devices (e.g., audio recorders)
used for data collection; if/how the instrument(s) changed over the course of the study
☑S12 Units of study →P5-7 Number and relevant characteristics of participants, documents, or events included in the study;
level of participation (could be reported in results)
☑S13 Data processing →P6 & 7
Methods for processing data prior to and during analysis, including transcription, data entry,
data management and security, verication of data integrity, data coding, and anonymization/
deidentication of excerpts
☑S14 Data analysis →P7 Process by which inferences, themes, etc., were identied and developed, including researchers
involved in data analysis; usually references a specic paradigm or approach; rationalea
☑S15 Techniques to enhance trustworthiness →P8 Techniques to enhance trustworthiness and credibility of data analysis (e.g., member checking, audit
trail, triangulation); rationalea
Results/Findings
☑S16 Synthesis and interpretation →P8-14 Main ndings (e.g., interpretations, inferences, and themes); might include development of a theory
or model, or integration with prior research or theory
☑S17 Links to empirical data →Table 1 Evidence (e.g., quotes, eld notes, text excerpts, photographs) to substantiate analytic ndings
Discussion
☑S18 Integration with prior work, implications,
transferability, and contribution(s) to the eld
→P14-21
Short summary of main ndings; explanation of how ndings and conclusions connect to, support,
elaborate on, or challenge conclusions of earlier scholarship; discussion of scope of application/
generalizability; identication of unique contribution(s) to scholarship in a discipline or eld
☑S19 Limitations →P20 Trustworthiness and limitations of ndings
Other
☑S20 Conicts of interest →P22 Potential sources of inuence or perceived inuence on study conduct and conclusions; how these
were managed
☑S21 Funding →title page P22 Sources of funding and other support; role of funders in data collection, interpretation, and reporting
aThe rationale should briefly discuss the justification for choosing that theory, approach, method, or technique rather than other options available, the
assumptions and limitations implicit in those choices, and how those choices influence study conclusions and transferability. As appropriate, the rationale for
several items might be discussed together.