1 Introduction

Bipolar spectrum disorders (BSDs) are a class of mood disorders characterized by periods of depression, hypomania, and mania. Additionally, episodes may contain mixed features of all three mood states [1]. Covered in depth elsewhere are the DSM-V diagnostic criteria for bipolar depression, mania, and hypomania [2]. The major categories of BSDs are subdivided into bipolar disorder type I, bipolar disorder type II, and cyclothymic disorder [2]; UpToDate 2022). The DSM-V may further specify BSDs as rapid cycling or seasonal pattern. Rapid cycling is four or more episodes of depression, hypomania, or mania in 12 months or less (UpToDate, 2022). A seasonal pattern entails at least one mood episode corresponding to a particular time of year for at least two years in a row—remission of this episode is also consistent with a specific time of year (UpToDate, 2022). Genetic and epigenetic risk factors for developing BSDs include a family history of BSDs, maternal exposure to war, maternal influenza infection during pregnancy, and exposure to illicit substances in utero. Additional correlations include childhood diagnoses of other psychiatric conditions, poverty, traumatic brain injury, and physical and sexual abuse [3]. Rolin et al. [4] found that BSDs are misdiagnosed as major depressive disorder in up to 60% of patients. The delay in proper diagnosis can lead to incorrect treatment with unopposed anti-depressant pharmacotherapy; this can precipitate treatment-related manic episodes. Bipolar depression also exerts a more considerable influence on workplace absenteeism or presenteeism than bipolar mania or unipolar depression [4].

Registered nurses (RNs) constitute the largest population of healthcare workers in the United States (American Association of Colleges of Nursing, 2022). RNs are twice as likely to suffer from depression compared to other professions due to high-intensity, hazardous, high-stress work environments [5]. However, the influence of BSDs on RNs is less certain. The purpose of this narrative review was to identify available evidence and gaps in understanding potential predictors, subjective experiences, and outcomes of BSDs in RNs. The research question was, “what risk factors and socioeconomic impacts do BSDs present to American RNs?”.

2 Methods

Review and approval from an Institutional Review Board did not apply to this article. The author searched the PubMed, CINAHL, and PsycINFO databases using multiple keyword combinations. Citation tracking was conducted through SCOPUS to capture additional literature. Article rigor and quality were not evaluated due to the scarcity of literature on the target population (Figs. 1, 2).

Fig. 1
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Initial article search process

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Fig. 2
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Refined article search process

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2.1 Inclusion criteria

To be included in this review, the articles had to be written in English. International articles were also included. There was no time limit for publication dates to capture all relevant articles.

2.2 Exclusion criteria

The author excluded articles that specifically discussed mental health conditions in nurses other than BSDs. Articles that were not found in academic databases were excluded. Two articles detail nurses' personal experiences of mental illness as a conglomerate sample [6, 7]. These articles did not mention BSDs by name; however, implicit themes experienced by those with BSDs, such as psychosis, grandiose thoughts, and mood instability, are present.

2.3 Data extraction

A table was used to extract key article information. The author noted the publication year, location, sample, study type, methods, and results (Table 1).

Table 1 Articles specific to bipolar spectrum disorders (BSDs) in registered nurses (RNs)
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3 Results

A total of eight articles ranging between 2000 and 2022 were included in this review. Five of the eight studies were personal narratives utilizing personal experience methods with the author as the subject [8,9,10,11,12]. All five of these articles were from the United States.

Two studies were mixed methods conducted through semi-structured interviews [6, 7]. Oates et al. [6] interviewed 27 mental health nurses (22 female, five male). Oates et al. [7] interviewed 26 nurses (21 female, five male). Both studies originated in the United Kingdom.

One study was a cohort study where shift work and psychiatric disorder associations were analyzed with Cox proportional hazards regression with age as the underlying time scale [13]. The sample included 19,964 working female nurses aged > 44 years old. Of these nurses, 5618 developed mood disorders, most among evening and night shift workers. This study took place in Denmark.

The selected articles are presented in a table (Table 1). The outcome measures and potential interventions arose from analyzed risk factors and socioeconomic themes. Risk factors included gender, stress, shift work, and sleep. Socioeconomic themes included economic impact and subjective experience.

3.1 Gender

Of the five identified BSD-specific articles discussing personal subjective experience, all were written by female authors [8,9,10,11,12]. The lifetime prevalence of BSDs in the United States in all individuals is estimated to be 4.4% [14]. Studies detailing epidemiological data regarding BSDs are scant, although some analyses suggest that BSDs, particularly subtype II, predominate in the female gender [15]. As of 2015, there were 3,187,672 full-time-equivalent RNs in the United States [16]. Of this population, 88% identified as female. Notably, suicide in female nurses is approximately twice that of non-nurse female-identifying individuals [8]. Additionally, one out of three individuals diagnosed with BSDs have attempted suicide at least once [9]. These statistics theoretically place female nurses diagnosed with BSDs at exceptional risk for suicide.

3.2 Stress, shift work, and sleep

All eight BSD-specific articles mention stress. Stress is intertwined with shift work and sleep because all three influence circadian alterations, as well as manic and depressive episodes [17, 18]. Hsieh et al. [19] found that stress-altered sleep patterns influenced depressive states.

Three BSD-specific articles explicitly discussed the role of shift work and sleep [6, 7, 13]. Nursing is among a handful of professions that require a 24-h, 365-day-a-year workforce. The definition of night shift or shift work for this review is working between 3 p.m. to 7 a.m. Using this parameter, Books et al. [20] found that 42.9% of the nursing workforce surveyed in the United States worked during these hours; the respondents were predominantly female (87.5%). It is well-established that alterations in circadian rhythm are a primary risk factor for symptom development in individuals with BSDs, along with other deleterious effects on metabolic and cardiovascular health [21,22,23]. Park et al. [24] discovered structural changes in the brains of shift-working nurses compared to those who worked days. The authors found decreased volume in the post-central gyrus, right paracentral lobule, and left superior temporal gyrus. Chen et al. [25] noted that individuals with BSDs displayed structural alterations in some areas, particularly the left superior temporal and post-central gyri. Alterations in these areas of the brain may contribute to auditory hallucinations, difficulty ascertaining the emotions of others, risk-taking, and emotional dysregulation [25].

With shift work’s contribution to sleep dysregulation, seasonal variations also intensify the effects. A study on Taiwanese nurses and seasonal sleep disruptions found that outpatient visits increased in the winter among nurses suffering from depression [26]. Altered melatonin levels in response to seasonal differences in sunlight correlate with manic or depressive BSD exacerbations [27].

Additionally, RNs are continuously exposed to artificial light sources while on the job. Excessive artificial light exposure, mainly blue light, has been linked to depression, hypomania, and mania [23, 28]. Interestingly, while depression correlates with shorter solar days, increased darkness exposure in the absence of either natural or artificial light decreased manic episode occurrences. Dark therapy is a complementary treatment to prevent or abort a manic episode [27, 29]. There is intriguing research regarding blue light-blocking glasses and the prevention of manic episodes in the general population [28].

Night shift nurses are at higher risk for absenteeism than their dayshift counterparts; absenteeism influences the development of depression and alcohol use disorders [30]. BSDs frequently accompany alcohol misuse and substance use disorders [31]. The Danish Nurse Cohort Study, one of the BSD-specific articles, corroborated these findings, linking mood disorders, including BSDs, to substance misuse among RNs [13]. Nurses' shift work, stress, and circadian disruption insinuate significant adverse health risks and co-morbidities, especially for individuals with BSDs.

3.3 Economic impact

The economic outcomes of BSDs in RNs, as well as other working professionals, are poorly understood. While only three of the BSD-specific articles briefly mention economic factors [10,11,12], the personal cost of these factors is noteworthy within the context of large-scale economic implications. One study estimated the total cost at more than $195 billion annually in lost revenue related to BSDs among all working professionals in the United States [14]. In 2013, the United States Bureau of Labor Statistics found that nurses comprise 4% of the total workforce in the United States [16]. This fact implies that at least $8 billion in BSD-related lost revenue may be attributed to nurses. The specific causes of this revenue loss are unknown.

Financial implications exert an influence on personal outcomes as well. Nurses were hesitant to disclose their diagnoses to work-sponsored insurance agencies. Wargo [12] discussed how BSDs excluded her from benefits such as life insurance coverage. Before diagnosis and during relapse, individuals faced extended leaves of absence for hospitalization [10, 11]. Although unquantified, this likely represents significant personal financial imposition. Absenteeism from their BSD-diagnosed peers could lead to an “absenteeism cascade” among co-workers due to stress from increased patient loads related to staff shortages. Absenteeism can also be correlated with lost revenue and benefits among all nurses, not just those with BSDs [30]. Until research quantifies economic aspects in this population, opportunities to decrease personal and systemic financial burdens remain uncertain.

3.4 Subjective experience

Outcomes regarding the subjective experiences of nurses with BSDs are scarce [8]. However, articles detailing this aspect comprise most of the specific literature on RNs with BSDs. Five of the eight BSD-specific articles focused on personal narratives [8,9,10,11,12]. Congruent with existing literature in non-RNs with BSDs, nurses tended to seek help with depressive episodes rather than during hypomanic or manic episodes and were associated with hospitalization [10]. Although there is no quantitative measure of how long it took for nurses to seek help, one may infer a longer-than-average delay to diagnosis. This deferral may be related to perceived professional stigma, financial concern related to time off work, and anxiety surrounding others’ perception of their suitability to return to work after hospitalization [32,33,34,35]. The Americans with Disabilities Act of 1990 protects employees from discrimination. It also explicitly states that bipolar disorder qualifies as a disability (Department of Justice, 2016). A common sub-theme was that nurses formally diagnosed with BSDs felt a need to conceal their symptoms from supervisors and peers, particularly amid an episode, despite these federal protections [9]. Unipolar depression was less stigmatized than BSDs among co-workers [10]. Some individuals experienced double standards when returning to work after leave, such as re-orientation to their work units, despite co-workers returning from extended maternity leave not needing to fulfill this requirement. Shame and humiliation frequently accompanied hospitalizations because nurses feared judgment from fellow RNs assigned to care for them [9]. Additionally, there was fear of repercussions, such as loss of licensure from the board of nursing; some locations require nurses to report hospitalizations related to mental illness [34]. While some nurses reported supportive co-workers and supervisors, others revealed that they were met with either indirect or outright disdain once their diagnosis was known [7, 10].

4 Discussion

This narrative review aimed to determine the risk factors and socioeconomic impact of BSDs among registered nurses. The author found eight papers specific to nurses with BSDs. These articles indicated that female nurses and nurses working night shifts are more likely to experience BSDs. Female nurses with BSDs are theoretically at a higher risk of suicide than their non-BSD peers. The literature also suggested economic implications through absenteeism, insurance coverage gaps, and income loss. Additionally, themes of shame and stigma were present in personal accounts of BSDs.

Stress, shift work, and sleep contribute to circadian alterations and the development of manic or depressive episodes. Environmental modifications relating to artificial lighting, seasonal changes, and altered melatonin production present further opportunities to prevent depressive and manic episodes. Blue light-blocking glasses to prevent mania in night shift nurses may be simple, cost-effective interventions [28]. Mitigating metabolic health risks, such as poor cardiovascular health and obesity from shift work, may be significant for nurses with BSDs. Antipsychotics often used to treat BSDs may compound these adverse metabolic outcomes [36]. With an increasing nursing shortage, creating a supportive work environment for individuals struggling with mental and physical health is critical to prevent attrition [5].

Another area requiring further investigation is the economic impact of BSDs in nursing. Data remains incomplete without knowing the incidence and prevalence of BSDs in nurses. However, one can infer opportunity costs from absenteeism, insurance coverage gaps, and hospitalizations. Work-sponsored interventions and preventive measures may contribute to decreased healthcare costs, improved staff morality, and retention.

Although the target population was American RNs, international literature supplemented insufficient existing information. Three of the studies originated from the United Kingdom and Denmark. Both countries have socialized medical systems, which differ structurally and financially from the United States healthcare system (New York State Department of Health, 2022). While the female gender still predominated internationally, cultural differences may influence the explored themes, such as economic impact, sleep patterns, and subjective experience.

Subjective experiences provided the most specific literature regarding BSDs in nursing. Areas of improvement in the healthcare environment include peer education regarding mental health issues in co-workers and the best ways to support and communicate within this context. Reminding nursing leadership that the Americans with Disabilities Act federally protects nurses with BSDs is crucial to foster a safe work environment without fear of retaliation (United States Department of Justice Civil Rights Division, n.d.).

4.1 Limitations and strengths

The major limitations of this review are the scarcity and quality of articles relating to the target population. Multiple excluded articles included randomized controlled trials, systematic reviews, and meta-analyses regarding RNs with other psychiatric disorders such as unipolar depression, anxiety, or post-traumatic stress disorder. Another potential confounding factor is that BSDs are often misdiagnosed as unipolar depression; they may also be more stigmatized than unipolar depression. This information implies that there are misdiagnosed RNs in studies about unipolar depression and individuals who may not disclose their BSD diagnosis.

The primary strength of this study is the novel findings. This review is the first of its kind to examine multiple issues affecting the target population.

5 Conclusion

The author identified risk factors and socioeconomic themes in this narrative review of BSDs among American RNs. These risk factors included gender, stress, shift work, and sleep and were associated with adverse psychological, neurological, and cardiometabolic effects. The themes of economic impact and subjective experience suggested modifiable outcomes, including absenteeism, exclusion from insurance, coverage, stigmatization, and hospitalization. Identifying risk factors and socioeconomic themes of importance will create a foundation for additional research, which may uncover additional areas of interest, including demographic information.