Clinical reviewInsomnia and health-related quality of life
Introduction
Despite Insomnia being recognised as a ‘24-hour disorder’ in both the major sleep nosologies,2, 3 historically, there has been less interest in the daytime aspects of insomnia compared with night-time symptoms and sleep parameters. Recent recommendations from leading researchers in the field*4, 5, 6 encourage further investigations into the waking consequences and correlates of insomnia. Indeed, clinical research in general, across a wide spectrum of illnesses, has moved towards a more holistic approach; looking beyond proximal symptoms, and viewing the patient within their wider psychosocial context.7
The purpose of this review is to: 1) give a brief overview of the known daytime consequences and morbidity associated with insomnia; 2) review work on the definition and measurement of quality of Life (QoL), or more specifically, health-related quality of Life (HRQoL), as it relates to insomnia; and finally, 3) outline a prospective research agenda, focusing on further understanding and measuring the extent to which insomnia, and it's treatment, impacts HRQoL and individual QoL.
Section snippets
Insomnia: daytime consequences and associated morbidity
Impairment in daytime functioning attributed to disturbed and/or poor quality sleep, features as one of the core diagnostic criteria for insomnia disorder.2, 3, 8 Clinician reports of patient consultations,9 and cross-sectional10 and prospective questionnaire studies,11, 12 reveal that individuals with insomnia report consistent decrements in mood and cognitive abilities (concentration, memory, attention), coupled with elevated levels of anxiety, fatigue and physical pain/discomfort, relative
Quality of Life (QoL) and Health-related Quality of Life (HRQoL)
In recent years there has been a shift towards assessing the overall impact of illness on aspects of QoL, through the measurement of HRQoL.48 QoL and HRQoL have become well established terms in the medical and health literature – indeed, a pubmed search reveals that published work with the term ‘Quality of Life’ in the title or abstract has risen more than fourfold in the last ten years (1998–2008: 62,641), relative to the previous decade (1988–1998: 14,428). This has occurred mainly because of
Does insomnia negatively affect HRQoL?
Given the reported daytime symptoms attributed to poor sleep2, 3, 8 it is reasonable to assume that individuals suffering from a chronic sleep problem may have a somewhat reduced ‘downstream’ HRQoL. Indeed, about two decades ago, the first studies began to appear focusing on the relationship between insomnia and HRQoL. Rombaut et al.60 created what they call the Quality of Life of Insomniacs (QOLI) questionnaire, a 59-item scale designed from the amalgamation of three other questionnaires
Does improving insomnia also improve aspects of HRQoL?
Because health-related functional impairments are prevalent within insomnia populations, and enshrined in the diagnostic criteria, treatment should ultimately target and alleviate such impairments. That is, improving sleep should improve functioning (this of course is based on the notion that impaired sleep is causally related to reduced HRQoL). Surprisingly, very few controlled studies (see Table 2) have included assessments of HRQoL (see91 for a review of more general daytime parameters), and
Reflections on existing insomnia-HRQoL treatment literature
From the limited treatment studies it is clear that improving sleep, in some cases, can lead to statistical improvements in aspects of HRQoL. However, what is far from clear is whether these improvements are clinically meaningful: do they really matter to the patient? For the most part, improvements are small and/or fall short of normative values, though this may be dependent on the particular population under investigation. Follow-up assessments have typically been short, with most occurring
Beyond generic measurement: future directions
Many questions remain unanswered about the nature of HRQoL in insomnia. The more basic ones, such as what are the predictors/mechanisms of HRQoL impairment and subsequent improvement will become apparent as researchers increasingly investigate insomnia as a 24-h disorder. Some possible targets include: sleep parameters; daytime symptoms like fatigue, mood, and neurocognitive impairment; dysfunctional beliefs; cognitive biases; and objective markers of the stress system. Longitudinal studies on
Conclusion
It is clear that insomnia does have a measurable negative impact on domains of HRQoL, and that these impairments are not simply limited to obvious domains, like vitality and energy, but also extend to other aspects of mental, social, and physical functioning. Comparisons with other illnesses, linear trends with insomnia severity, and additive effects of insomnia beyond a primary/co-occurring illness, all support and strengthen this perspective. Although research into HRQoL is in its infancy
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