Introduction

It is becoming widely noted that sleep disorders are often associated with serious illnesses. Reports show that the sleep length is closely related to the incidence of obesity, diabetes, hypertension, dyslipidemia, and ischemic heart disease [1, 2]. Sleep duration is the shortest for both males and females in their active years from ages 45 to 49 years [3]. Recent clinical experience has shown the onset of acute aortic dissection (AAD) to appear at earlier ages, and we suspect that sleep disorders are closely related to the increased incidence of AAD in the active years. The aim of the present study was to assess the relationship between AAD and sleep disorders in a working population.

Clinical summary

Between January 2006 and December 2010, 291 patients were transferred to our hospital because of AAD (type A 158 patients, type B 133 patients). Of these, 139 (type A 67, type B 72) patients were younger than 65 years and had a job requiring active duty. Subjects with Marfan’s syndrome were excluded from the analysis. One hundred and seven patients were male. The average age was 54.3 ± 8.5 years, ranging from 28 to 64 years. All patients had marked hypertension at the time of AAD onset (mean systolic blood pressure 185.7 ± 14.3 mmHg, ranging from 166 to 220 mmHg), but only 42 patients (30.2%) were aware of their hypertension and had been visiting their family doctor. Institutional Review Board approval was obtained before publication of this article and reporting of this information.

All patients were interviewed (or their families if they underwent emergency surgery) to determine their occupational status and whether they experienced mental or physical stress due to their job. We also assessed whether they had sleep disorders such as insomnia (the condition of being unable to sleep) or sleep deprivation (not enough time to sleep), or typical symptoms of sleep apnea syndrome (SAS), such as snoring or daytime sleepiness. Furthermore, polysomnography was provided for the patients when they were discharged from the hospital, and an apnea–hypopnea index (AHI) >5 points was defined as SAS.

Seventy patients (50.4%) were found to suffer from sleep disorders (65 males, 5 females). Most of these patients had irregular daily schedules due to job pressure, as shown in Table 1. Sixty-six (94.3%) complained of severe mental and physical stress in daily life. Insomnia was reported by 35 patients (50%), and sleep deprivation by 31 (44.3%). The most frequent indicator of a sleep disorder was SAS symptoms, which were found in 43 patients (61.4%). These sleep disorders were complicated in many patients. SAS was diagnosed in 43 patients (61.4%), all male, by polysomnography (Fig. 1). Their average AHI was 22.0 ± 7.5 points, indicating severe SAS requiring appropriate treatment.

Table 1 Occupational status of patients with sleep disorders (n = 70)
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Fig. 1
figure 1

Prevalence of sleep disorders and stress from daily life

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Discussion

Approximately 90% of AADs are caused by hypertension. A large epidemiological study covering the active ages showed that the incidence of hypertension among patients with sleep disorders was double that of those without sleep disorders [4]. Adrenergic stress is increased by shortening the duration of sleep or lowering the sleep quality. It is evident that workers who perform overtime work suffer markedly from refractory hypertension due to the persistent day-long activity of the adrenergic nervous system [5]. King et al. [6] reported that sleep disorders were a risk factor for coronary atherosclerosis. Ikehara et al. [7] also described that sleep disorders were associated with increased mortality from cardiovascular disease. Accordingly, SAS and other sleep disorders similarly affect human health by reducing the duration and quality of sleep.

It is well known that work-related stress, both mental and physical, is strongly associated with impaired sleep. In the present study, more than 90% of the patients complained of such stress. The character of the work itself is affected by the current economic depression in Japan. Middle managers worry about their company’s slack business and are always afraid of being a burden on the company. Small business owners are also unable to sleep long enough or well enough due to their company’s problems. Drivers and journalists unavoidably suffer sleep deprivation due to their irregular daily workloads. Recent advances in internet technology and the world trade system may make some aspects of life easier and facilitate business, but the person in charge has no choice but to remain available to overseas contacts all night long. This necessarily adds pressure to daily life and precludes such workers from maintaining a regular and healthy sleep schedule. In advanced nations, therefore, mental and physical stress is increasingly a normal part of life, exacerbating SAS and other sleep disorders caused by overtime work that did not exist in the earlier times.

As mentioned above, sleep disorders are considered one of the risk factors for the occurrence of AAD in patients of active ages. During the primary care for patients with mental or physical stress brought on by their daily life activities, it is important to assess them for the presence of sleep disorders. If patients have marked sleep disorders or severe SAS, appropriate treatment is essential to prevent refractory hypertension and subsequent AAD.