Insomnia among patients with advanced disease during admission in a Palliative Care Unit: a prospective observational study on its frequency and association with psychological, physical and environmental factors

BACKGROUND: The aims of this study were: 1) to assess the frequency of insomnia among patients during admission in a Palliative Care Unit (PCU); 2) to study the association between emotional distress and insomnia, taking physical, environmental and other psychological factors into account. METHODS: Prospective observational study including patients consecutively admitted to a PCU during eight months, excluding those with severe cognitive problems or too low performance status. Insomnia was assessed by asking a single question and by using the Sleep Disturbance Scale (SDS), and emotional distress using the Hospital Anxiety and Depression Scale (HADS). Physical, environmental and other psychological factors potentially interfering with sleep quality were evaluated. Association between insomnia and the factors evaluated was studied using univariate and multivariate regression analyses. RESULTS: 61 patients were included (mean age 71.5 years; 95% with oncological disease); 38 (62%) answered “yes” to the insomnia single question and 29 (47%) showed moderate to severe insomnia according to the SDS. 65% showed clinically significant emotional distress and 79% had nocturnal rumination. The physical symptoms most often mentioned as interfering with sleep quality were pain (69%) and dyspnoea (36%). 77% reported at least one environmental disturbance. In the univariate analysis, answering “yes” to the insomnia single question was significantly associated with higher HADS score, anxiety, nocturnal rumination, clear knowledge of the diagnosis, higher performance status and dyspnoea; moderate to severe insomnia was significantly associated with nocturnal rumination, higher performance status, environmental disturbances and daytime sleepiness. In the multivariate regression analysis, answering “yes” to the single question was associated with dyspnoea (OR 7.2 [1.65-31.27]; p = 0.009), nocturnal rumination (OR 5.5 [1.05-28.49]; p = 0.04) and higher performance status (OR 14.3 [1.62-125.43]; p = 0.017), and moderate to severe insomnia with nocturnal rumination (OR 5.6 [1.1-29.1]; p = 0.041), and inversely associated with daytime sleepiness (OR 0.25 [0.07-0.9]; p = 0.043). CONCLUSIONS: Insomnia was highly frequent. Several physical, psychological and environmental factors seemed to influence insomnia. Within the multimodal management of insomnia, the assessment of nocturnal rumination may be of particular interest, irrespective of emotional distress. Further studies with larger sample sizes could confirm this result.