Sleeping difficulties and health‐related quality of life in Parkinson's disease
The underlying link between poor HRQL and sleep quality is not fully understood. One may speculate on potential mechanisms; for example, an unrecognized confounder (such as sleep‐disordered breathing) may lead both to an increased need for sleep and poor quality of life. Epidemiologic evidence propounds that short and long sleep, that is, participants who reported sleeping either ≤6 hours or ≥8 hours, is associated with mortality,7 and insomnia with cardiovascular disease.8 Self‐reported long sleep duration (≥9 hours) was associated with increased risk of dementia‐specific mortality.9 Finally, excessive sleep‐related symptoms can lead to diminished HRQL per se.
Health‐related quality of life can be assessed by self‐rated health (SRH), which is a valid and consistent predictor of cardiovascular morbidity10 and overall mortality.11 SRH is a single question, whereas the 5‐item World Health Organization Well‐Being Index (WHO‐5) is a highly useful tool that can be applied in research studies to assess well‐being over time or to compare well‐being between groups.12
Older adults are particularly susceptible to comorbidities that are known to overlap with sleep disorders. James Parkinson, in 1817, wrote about sleep and HRQL in the late stage of PD as “and at the last, constant sleepiness, with slight delirium, and other marks of extreme exhaustion, announce the wished‐for release.”13
The aim of this study was to evaluate, by means of a structured questionnaire approach, the occurrence between sleep‐related symptoms, HRQL, comorbid sleep disorders, and other comorbidities in a non‐selected population of patients with PD.