Insomnia symptoms and daytime function in stable heart failure.

HEART FAILURE (HF) IS A DISABLING CHRONIC CONDITION THAT AFFLICTS OVER 5 MILLION AMERICANS1 AND IS ASSOCIATED WITH DECREMENTS IN functional performance, depression, excessive daytime sleepiness, and fatigue. As many as 73% of people with chronic heart failure (HF) report poor sleep quality,2–9 and many have poor sleep continuity.10–13 Insomnia symptoms are also common.7–9 Understanding the nature of insomnia symptoms and their associations with daytime symptoms and functional performance is necessary to guide sleep disorders treatment for HF patients. People with HF report insomnia symptoms, including difficulty maintaining sleep (34% to 43% of sampled patients),7–9 falling asleep (23% to 47%),7–9 and waking too early in the morning (35% to 39%)7–9 in studies of HF patients awaiting transplant HF,8 hospitalized HF patients,9 and a small group of patients in a structured HF management program (n = 59).7 HF patients were consistently more likely to report difficulty initiating and maintaining sleep and to have objective evidence of prolonged sleep latency and poor sleep continuity than a comparison group recruited from the same community,7 and rates8,9 are higher than those reported by adults responding to the Sleep in America Poll.14 HF was associated with more than a two-fold increased risk of self-reported insomnia in a large community study.15 Although sleep disordered breathing (SDB) occurs in approximately 50% of HF patients10,11,16–26 and is often associated with difficulty maintaining sleep, few, if any studies have addressed the potential associations of SDB or polysomnographically recorded sleep characteristics with insomnia symptoms among HF patients. Insomnia symptoms are associated with impaired functional performance, including decrements in exercise capacity,5 6-minute walk test distance (6MWT),27 and self-reported physical function,9,27,28 but others have not found relationships in people with HF.8,29 To our knowledge, the extent to which clinical and demographic variables contribute to the relationships between insomnia symptoms, daytime symptoms, and functional performance has not been addressed. The objectives of this study were to examine the extent to which: (1) patients with stable HF report insomnia symptoms (Difficulty Initiating and Maintaining Sleep - DIMS); (2) demographic and clinical patient characteristics and SDB explain DIMS; and (3) self-reported DIMS is associated with daytime symptoms (depression, fatigue, excessive daytime sleepiness) and functional performance (6MWT and self-reported physical function), while accounting for SDB and potentially relevant clinical and demographic characteristics.