Background and rationale {6a}
Insomnia is very common and is defined as dissatisfaction with sleep quantity, sleep quality, or both, due to difficulties initiating and/or maintaining sleep, for at least 3 nights per week, for a period of at least 3 months [
1]. Within industrialised societies, approximately 6–10% of the population have insomnia, where prevalence rates have increased in recent years; additionally, up to 48% of the population report the presence of insomnia symptoms [
2,
3]. Therefore, insomnia is a highly prevalent problem. Insomnia disorder (beyond 3 months) is associated with a significant economic burden [
4] and is a risk factor for a range of physical health conditions including hypertension, cardiovascular diseases and psychological conditions including depression [
5‐
7].
Theoretical models of insomnia (e.g. Spielman’s “3P” model) suggest that psychophysiological arousal caused by a stressful life event can cause a short-term disruption to sleep (i.e. acute insomnia) [
8,
9]. Over time, this can result in maladaptive compensatory behaviours, such as spending excessive time in bed or becoming preoccupied with sleep, which consequently creates a long-term problem of poor sleep through behavioural conditioning [
10]. Acute insomnia is common, where the annual incidence rate is potentially as high as 27 to 37% [
11,
12]. One study has demonstrated that approximately 7% of individuals with acute insomnia subsequently go on to develop insomnia disorder, and a further 20% of individuals demonstrate variable sleep disturbances and may go on to develop insomnia disorder, albeit at a slower rate [
12]. Given the associated individual and economic health burden associated with insomnia disorder, strategies which prevent the transition from acute to chronic insomnia are important.
Previous naturalistic studies have indicated that stressful events, in the form of natural disasters such as earthquakes or hurricanes, or events such as war, can disrupt sleep [
13‐
16]. The ongoing COVID-19 pandemic may represent one such stressful life event. A recent meta-analysis has demonstrated that the global prevalence of sleep problems during the COVID-19 pandemic is high, where approximately 40% of the general population and healthcare workers are affected by sleep disturbances [
17]. Individual fear of infection, or perceived infection severity, may also represent a stressor in the context of the COVID-19 pandemic. For example, one cross-sectional study from China demonstrated that sleep disturbances were common, and people who believed that COVID-19 had caused a higher number or deaths or that COVID-19 was not easy to cure, were more likely to experience sleep disturbances [
18]. Additionally, one Italian study has indicated that as well as poor sleep quality being very common, individuals who had a greater fear of direct contact with people infected by COVID-19, and those with an uncertain COVID-19 infection status, had an increased risk of developing sleep disturbances, and higher anxiety and distress [
19]. Therefore, COVID-19 sleep disturbances are extremely likely, and early interventions may present an opportunity to prevent a short-term sleep disruption from becoming a long-term clinical sleep problem [
20].
Pharmacological treatments, such as benzodiazepines, are often used in the management of insomnia and can be effective treatments in the short term [
21]. However, pharmacological agents are associated with a range of side effects and adverse outcomes, including drowsiness, tolerance, dependency and negative impacts upon next-day cognition, in addition to increased mortality and suicide risk [
21‐
24]. In particular, the use of pharmacological agents is particularly problematic in older adults [
25]. Therefore, non-pharmacological alternatives are necessary.
One non-pharmacological treatment, which is highly effective in the treatment of chronic insomnia, is cognitive behavioural therapy for insomnia (CBT-I) [
21]. CBT-I is a structured psychotherapy with the aim of identifying and changing maladaptive cognitions and behaviours which contribute to the maintenance of insomnia [
26]. CBT-I results in equivalent improvements to those observed using pharmacological treatments, with the benefit of being more durable (compared to pharmacological treatment discontinuation) and concomitant reductions in symptoms of anxiety and depression [
21]. For these reasons, CBT-I is recommended as a first-line treatment for chronic insomnia [
21]. However, the widespread delivery and uptake of CBT-I is prevented by the lack of qualified providers and high attrition levels [
20]. Therefore, traditional CBT-I may be too time- and resource-intensive to be feasible and practical in the treatment of acute insomnia, and shorter interventions are likely to be of benefit.
One previous study found that the use of a self-help leaflet (based on stimulus control, cognitive control and imagery distraction techniques), delivered alongside a 60–70 min single (“one shot”) session of face-to-face CBT-I for acute insomnia, effectively reduced insomnia severity [
20]. Furthermore, follow-up studies have demonstrated effectiveness when the leaflet has been used alongside CBT-I treatment, in a group format and in a male adult prison population [
26,
27]. Internet-based interventions can be used to deliver treatment to more individuals than face-to-face therapists, with lower relative costs [
28]. Therefore, this self-help leaflet is well-suited to an online delivery model and can be used to reach a large number of people in the context of a large-scale stressful event. Indeed, internet-based CBT-I has been shown to be effective, with similar effect sizes to face-to-face treatments [
29]. In further support of an online delivery model, recent studies have also demonstrated that sleep extension does not occur in the context of acute insomnia [
30,
31]; therefore, incorporating sleep restriction is not necessary. This intervention may also aid the prevention of sleep problems in individuals with good sleep, where the stress of a naturalistic event can still cause sleep disturbances [
13‐
16]. Therefore, this study will examine if an online self-help leaflet is effective in reducing symptoms of acute insomnia in poor sleepers. This study will also examine how long the effects last for at follow-up stages, and finally, investigate if the leaflet can prevent the development of poor sleep in good sleepers.