in 2015 who is undiagnosed is $6366 as compared to the healthcare costs for someone who is diagnosed and being treated was $2105.
2 It has been determined that worldwide the prevalence of sleep apnea now approaches nearly one billion (936 million) people [13], based on a review of the data available from 16 countries and considering people age 30–69. When considering those who have more moderate to severe sleep apnea the prevalence is 425 million. The impact was most significant in China and then the United States followed by Brazil and India.
Prevalence of Insomnia
For insomnia the prevalence may vary based on the study but in general it appears to be around 33% of the population [2]. The majority of the insomnia complaints focuses on the inability to maintain sleep. Percentages will vary based on the defined criteria that may exist as a result of the specific study parameters. There are two frequently cited studies regarding the prevalence of insomnia. The first indicates that 29.9% of people report insomnia symptoms and 9.5% satisfy the criteria for a diagnosis [14]. Second, it was found that 34.5% of the population had at least one of three symptoms that were present three nights per week and 9.8% were found to have symptoms along with daytime complaints [15]. It is important to understand that insomnia is the most frequent complaint in a primary care practice.
Prevalence of Restless Leg Syndrome (RLS)
The prevalence of RLS, or Willis–Ekbom disease as it is currently termed, is estimated to be between 2.5 and 10% of the general population [16]. Many of the studies have limitations due to misdiagnosis and because patients may not seek medical care. With improved criteria for making a diagnosis the recognition of RLS may actually result in an increased prevalence. A study in 2012 reviewed a variety of previously published studies [17]. In general, the outcome is that the prevalence is between 3.9 and 15% but may vary depending on the structure of the study. Other reported findings are that RLS appears to be more prevalent in females, less common in Asia, and can be worse with age and some health issues.
Increasing Awareness of Narcolepsy
Narcolepsy is another sleep disorder that has been studied epidemiologically. At the present time, its prevalence is between 25 and 50 people per 100 000 [18]. Currently, it is stated that narcolepsy has a similar prevalence to multiple sclerosis. A more current publication indicates that the prevalence is 1 for every 2000 people and it is estimated that about 50% may be undiagnosed [19]. Over the upcoming years more research will be done, and as more data is gathered the actual prevalence of Narcolepsy will be better defined and hence the recognition as well as management strategies should improve.
Risk Factors
There are a multitude of risk factors that may impact the onset as well as the progression of a specific sleep disorder. The risk factors may be different for each specific sleep disorder and overlapping risk factors may be present that apply to a number of different sleep disorders and are becoming increasingly common. In general, the demands of modern‐day life have impacted the quality of one’s sleep as well as the required amounts that are deemed appropriate. In addition, the disruption of an individual's sleep can impact other family members, roommates, or one's bed partner. As an example, a study published in the Mayo Clinic Proceedings as it relates to sleep related breathing disorders (SRBD) clearly demonstrated that the snoring of one person significantly impacted the sleep of the bed partner to the point that the effected person had symptoms that were worse than those of the snorer [20].
The more common risk factors associated with the three most common sleep disorders as previously discussed are discussed elaborately in other chapters (Table 1.1).
The prevalence of sleep problems related to comorbid illness is well recognized. The more health‐related problems that exist the greater the chances that a sleep disorder as well as sleep complaints may be related. This is especially true when one considers people who are older; however, the comorbidities were found to be more significant than age [21]. The number of morbidities reported in another study, referred to as multi‐morbidities, correlated mostly to reports of sleep duration, short as well as long sleep, and to sleep quality [22]. Alteration in sleep duration as well as sleep quality may be associated with a number of chronic health issues as well. This study demonstrates that the presence of multi‐morbidities in conjunction with sleep quality and duration poses concern from a public health point of view (Table 1.2).
Health Consequences and Related Costs
The impact of sleep disorders on one's health can present in a variety of ways. It is now well recognized that a wide variety of health issues potentially may arise as a result of sleep disorders. In addition, at times an illness or health problem can conversely impact one’s sleep. For the sake of clarity, the one’s of greatest importance and the most frequently encountered will be reviewed here.
The increased risk for CVD and elevated blood pressure associated with SRDB are well documented. The largest and the most cited study, the Sleep Heart Health Study, took place between 1995 and 1998 as a multicenter cohort study with over 6000 people age 40 and above as participants [23]. The results of this study found that sleep apnea along with other SRBDs are risk factors for CVD which is inclusive of myocardial infarction and stroke. A variety of mechanisms are proposed indicating that sleep apnea and CVD are related with elevated blood pressure as the more common finding.
Alteration in metabolic and endocrine function is also associated with an SRDB, the most prevalent of which is type 2 diabetes. It has been found that snoring alone increases the risk for type 2 diabetes independent of any other risk factors [24].
Table 1.1 Common risk factors.
| Sleep‐related breathing disorders |
| Increased incidence with age |
| Frequent and loud snoring |
| Mouth breathing – difficulty in nose breathing |
| Gasping for air during sleep |
| Associated with larger neck and waist size |
| Increases with weight gain |
| Males have greater risk than females |
| Airway obstruction – especially large tonsils and adenoids |
| Hypothyroidism |
| Coexisting cardiovascular disease or hypertension |
| Allergy or asthma |
| Family history |
| Insomnia |
| Increases with age |
| Associated with anxiety and/or depression |
| Associated with pain, headaches, arthritis, temporomandibular Joint (TMJ) symptoms |
| Dissatisfied with one's quality of sleep |
| Females have greater risk than males |
| Substance abuse |
| Perceives health as worse or bad |
| Level of schooling |
|
Restless limb syndrome (RLS)
|