Age specific prevalence of sleep problems and anxiety disorder: Data from the Lifelines cohort

Anxiety disorders are the most prevalent mental disorders in the general population, associated with high health care costs and a high burden of disease [1].  Estimates of the 12-month prevalence rates of anxiety disorder have ranged between 10% - 21% [2]. With regards to specific anxiety disorders, panic disorder (0.7%-5.3%), agoraphobia (1.0%-4.0%), generalized anxiety disorder (GAD)  (0.9%-5.9%), social anxiety disorder (SAD) (2.4%-7.4%), specific phobias (5.5%-12.1%) are the most frequent disorders[2–9]. They are most common in women [9]. Although effective psychological and pharmacological treatments exist for anxiety disorders, they tend to be persistent or recurrent [10] and many affected individuals do not contact health services for treatment [11, 12]. Therefore, prevention and intervention of anxiety disorders are still one of the most important issues in the public health area.

Sleep problems also occur frequently. For instance, approximately 30% of the adults in studies including adult samples have at least one sleep problem (difficulty initiating or maintaining sleep, waking up too early, and poor quality of sleep) [13]. In a study including adults aged between 18-89 from the general population, the prevalence of self-reported sleep problems was 52.3% [14]. Morthy and colleagues found that older adults (>65yr) were more likely to report sleep problems than younger adults (18-35yr) (65% versus 43%) [15]. More recently, Grandner et al. found the highest prevalence of sleep problems in the youngest age group (18-24yr) and the lowest prevalence of sleep problems in the oldest group (older than 80 yr women and 70-74yr in men [16].  Moreover, women reported more sleep problems compared to men across all age groups[16, 17].

Considerable evidence suggests that a higher age is associated with a decreased risk of anxiety disorder but increased self-reported sleep problems across the lifespan. Anxiety disorders generally start in childhood and adolescence, and 12-month prevalence rates increase in early adulthood (18- to 34-year) until they reach a peak in middle age (35- to 49- year), then tending to decrease again with older age (50- to 64-year) and lowest rates are reported in the elderly (65-to 79-year old) [18, 19]. A meta-analysis of age-related sleep changes shows that self-reports demonstrate that increased age is associated with increased frequency waking after sleep onset, and decreased total sleep time [20].  Although changes in sleep being accepted as part of normal aging, sleep disorders and sleep problems are increased with age [15].

Sleep problems are linked to many mental disorders, including anxiety disorders. Odds ratios for various anxiety disorder diagnoses associated with lifetime sleep problems varied from 1.2 to 13.1 [21]. In the primary care setting, 41% of total participants reported sleep problems, and adults who reported sleep problems were more likely to report anxiety symptoms[22]. Many epidemiological studies investigated the relationship between the occurrence of anxiety disorder and sleep problems in older age groups (65 years and older) [23, 24]  and younger adults (18-30 years) [25–27] comparing older and younger age groups. However, less research has been conducted to the co-occurrence of anxiety and sleep problems in a middle age group (35-60 years). In addition, previous most studies included small, nonrepresentative samples, limiting the generalizability of the findings.

With regards to specific anxiety disorders, self-reported sleep problems are extremely common in patients with panic disorder and GAD [21]. According to DSM-V, sleep problems are part of the diagnostic criteria of GAD and a high prevalence of sleep problems are expected in GAD.

Beside the association between anxiety and sleep problems among the adulthood sample, in the development of anxiety and sleep problems, adolescence also should be concerned as  a critical period [28]. This transition from child to young adulthood is characterized by significant biological, psychological, and social changes, which may result in alterations in emotion regulation and delayed circadian phase[29]. Anxiety and sleep problems often increase during adolescence [30, 31], and the quantity and quality of both symptoms domain changes further in adults [23].  Anxiety symptoms first decrease during early adolescence and subsequently increase from middle to late adolescence [32, 33], In contrast, sleep problems were reported more at early than middle and late adolescence [33]. Comparing to the mid-1990s, a time-series analysis shows that the trend of  sleep problems among  adolescents increases approximately twofold in the end of the 2000s  [34]. Overall prevalence of anxiety and sleep problems were higher in girls rather than boys [30, 32].

The overall aim of the study is to estimate the prevalence rates of anxiety disorder and sleep problems among the general population over the life course, and to examine the relationship between anxiety disorder and sleep problems. For this aim we will use data of the Lifelines cohort study. Lifelines is a large, multi-generational, prospective cohort study from the northern population of the Netherlands, examining a broad range of risk factors (physical, biomedical,  behavioral and mental health) that contribute to the health and disease of the general population. In addition, we will estimate age and sex effect on prevalence of anxiety disorder and sleep problems.  Furthermore, we investigate association between anxiety disorder and sleep problems by age (young, middle and old age group) and sex. Finally, we will test whether the associations between sleep problems and anxiety differ across individual anxiety disorders.