When I was asked to write a blog on sleep and heart failure (HF), I wondered, "How much do my nursing colleagues know about this topic?" I asked myself this question because not much on sleep and its importance was discussed during my nursing education, and I have not learned much about these topics in 12 years of clinical practice. What piqued my interest in sleep research is the physiology of sleep and the potential of using biophysiologic markers to link symptoms to underlying changes associated with poor sleep. While sleep research has gained more attention and interest, information on sleep in persons with HF, particularly those with advanced stages of HF, is comparatively limited. In this blog I will discuss the requisites of healthy sleep, the prevalence of sleep problems in patients with HF, methods of assessing sleep and the associated challenges, treatment for sleep disorders and directions for future research.
What Are the Requisites of Healthy Sleep?
Sleep is vital for health functioning and for recovery from illness. Healthy sleep is essential for cognitive function, psychological well-being, and cardiovascular, cerebrovascular and metabolic health. The requisites of healthy sleep include adequate sleep duration, appropriate timing, regularity, the absence of sleep disturbances or disorders and good sleep quality. The American Academy of Sleep Medicine and Sleep Research Society recommends that the average adult should sleep seven or more hours per night on a regular basis to promote optimal health. Good quality of sleep is defined as falling asleep soon after getting into bed (less than 30 minutes), sleeping through the night, and awakening no more than once per night. Sleep disorders and sleep deprivation are associated with deterioration in human body functioning and increased cardiovascular risk, including HF.
Sleep Disorders in Persons With HF
HF, a chronic irreversible condition in which the heart cannot pump adequately, affects an estimated 6 million Americans. Approximately 75% of individuals with HF experience sleep disturbances, which are often the result of the disease itself and HF-related symptoms (e.g., nocturnal dyspnea, cough and palpitation). Further, sleep disorders, such as sleep-disordered breathing (SDB) and insomnia, contribute to poor sleep in persons with HF. SDB (composed of obstructive and central sleep apnea) affects up to 71% of persons with HF and contributes to respiratory sleep disturbance and adverse clinical outcomes. Worsening cardiac function induces SDB. Conversely, SDB adversely affects the progression of HF as a result of intermittent hypoxia, increased preload and afterload, sympathetic nervous system activation and vascular endothelial dysfunction.
Insomnia, characterized by symptoms of difficulty falling asleep, difficulty staying asleep and undesired early awakening, is highly prevalent in patients with HF. More than 50% of people with HF report at least one insomnia symptom. Insomnia is associated with older age and worsening HF, as defined by the declining New York Heart Association functional class. SDB and insomnia lead to poor sleep quality and may result in daytime symptoms (e.g., excessive daytime sleepiness). Sleep-related daytime symptoms and poor sleep quality compromise quality of life. In HF, impaired daytime function is associated with poor medication adherence and inadequate self-care.
How Do We Assess Sleep?
As clinicians and researchers, we need to keep in mind that sleep is a multiple-dimensional concept. As a result, assessing sleep involves using subjective and objective sleep measures. Examples of subjective measures of sleep are patient-reported outcomes gathered through questionnaires, surveys or sleep diaries. Objective measures of sleep include using devices/technologies to collect behavioral and physiologic data. Examples of such devices/technologies are actigraphy, polysomnography (PSG) and wearable/digital technologies. Objective measures of sleep help uncover the underlying pathology of poor sleep. Integrating objective measures with subjective data enriches our understanding of antecedents of poor sleep and linking symptoms to these antecedents.
Examples of Objective Measures of Sleep
Actigraphy is a validated objective method measuring sleep parameters and average motor activities using noninvasive accelerometers. Many wearable commercial smart devices on the market, such as Fitbit, and Garmin and Apple watches, integrate actigraphy/accelerometers within the device. An actigraphy device looks like a wristwatch, typically worn on a nondominant hand when data is collected. The data collection process occurs over several days or weeks, and actigraphy is designed to not interfere with regular daily routines. Based on individuals' movements, actigraphy calculates sleep parameters such as the time an individual goes to sleep, the time of waking up, how long it takes to fall asleep, the duration of sleep, and how much time they spend awake during the night after falling asleep. Since actigraphy relies on interpreting movements, it can only be used in detecting certain sleep disorders, such as insomnia and circadian rhythm sleep-wake disorders.
On the other hand, diagnosis of SDB has traditionally been based on overnight PSG in a sleep laboratory. PSG involves continuous recording of physiologic variables, such as nasal airflow, chest/abdominal movements, brain activity, cardiac rhythm and heart rate, and oxygen saturation. In addition, patients or research participants are required to sleep in a laboratory, which is a strange environment where sleep data is being collected and may influence overall sleep quality.
WatchPAT, a newly developed home sleep apnea test (HSAT) device integrating advanced actigraphy, peripheral arterial tonometry (PAT), heart rate and oximetry, can uncover physiologic changes in sleep. The reciprocal pattern derived from the device – decreased PAT amplitude and increased heart rate – indicate sympathetic nervous system activation, which is associated with the termination of respiratory-related events, such as apnea. The decreased PAT amplitude indicates vasoconstriction, and the increased heart rate reflects the termination of apnea events.
Challenges in Sleep Evaluation
While PSG is considered the gold standard for sleep diagnostic tools, using it to diagnose SDB presents many challenges: 1) Patients often need to be connected to many tubes and wires, which is an off-putting experience, 2) PSG is expensive, even with insurance coverage, and 3) due to the limited availability of sleep centers and sleep specialists, there are often lengthy waits to get PSG studies completed and possible delays in the interpretation of PSG results.
The technology for wearable devices and HSAT has advanced significantly. However, further research may be needed for patients with more severe sleep disorders and more complex cardiac conditions, such as advanced-stage HF. It is crucial to remember that persons with advanced-stage HF often have other comorbidities, which may complicate the process of assessing sleep. Given the heavy burden associated with chronic conditions, clinicians and researchers need to look for easily accessible methods for evaluating sleep in such populations. Although it is possible to use wearable devices/digital technology to assess sleep in persons with HF, clinicians and researchers must interpret sleep data cautiously, particularly in patients with severe disease conditions.
Treatments for Sleep Disorders in HF
Sleep hygiene and education are nonpharmacological treatments commonly used to improve sleep quality. These two interventions aim to change behaviors that hinder good sleep quality, such as frequent daytime naps and excessive caffeine consumption. Efficacious treatments for insomnia include hypnotic medications and cognitive behavioral therapy for insomnia (CBT-I). Literature indicates that patients prefer behavioral treatment rather than hypnotics due to the possible associated adverse daytime effects of hypnotic regimens.
CBT-I is a multimodal behavioral self-management intervention addressing perpetuating factors for insomnia, including dysfunctional thoughts, beliefs and behaviors. Compared with hypnotic medications, CBT-I demonstrated more long-lasting effects on insomnia. Since medication regimens for managing patients with HF often include classes of different medications, providers need to cautiously evaluate patients to determine what might be the most appropriate therapy. A collaboration between sleep specialists and cardiologists may be necessary to manage patients with sleep disorders and complex cardiac conditions. Separately, for persons with suspected SDB, early detection of such conditions is crucial. Assessing compliance and effectiveness of positive airway therapy would be detrimental for individuals with HF and SDB.
Future Directions
Sleep and Cognition in Those With HF
Linkages between sleep and cognition in persons with HF may require further studies. Poor quality and disrupted sleep are common in an aging population and the features of many neurological and psychological conditions, including Alzheimer's disease and depression. Further, aging is a risk factor for all cardiovascular diseases, and the prevalence of HF usually rises with increased age. Age-related changes in brain structure are associated with cognitive impairment, and the prevalence of cognitive impairment in those with HF is up to 75%. In the general population, sleep deprivation may induce adverse changes in cognitive performance, including impaired attention, vigilance, working memory, long-term memory and decision-making. While sleep quality usually worsens with age, it also may be part of why the brain in the HF population is more vulnerable to developing cognitive impairment and neurodegenerative conditions. Loss of sleep may be a driver of the underlying problem. It is also possible that unknown cellular changes are associated with aging in the setting of vascular changes in the brain of people with HF. Further research will help promote an understanding of neuropathological changes in these conditions.
Wearables/Digital Technology for Assessing Sleep
Commercial devices may be used to collect sleep data. As discussed earlier, many commercial devices integrate actigraphy/accelerometer technology, and these devices can capture some behavior and physiologic data that can be used to assess sleep. Not only is further research needed for validating these devices/technologies, but clinicians and researchers also must consider when it is appropriate to use such data. Who owns the data, who may use it, and who will benefit from using the data are additional questions.
Integrating Subjective Measures in Electronic Health Records
Integrating subjective measures of sleep in electronic health records (EHRs) will make assessment of sleep more accessible. We, as clinicians and researchers, hope to see more subjective measures, particularly patient-reported questionnaires, integrated into the EHR to make screening sleep problems more easily accessible. Some questionnaires, such as the Patient-Reported Outcomes Measure Information System (PROMIS) developed by the National Institutes of Health for clinical research and practice, can be easily embedded in the EHR and administered to the patient while waiting for their clinical appointments. EHR has the power to transform our practice but needs to be used to its full potential. From a practice standpoint, we should not only ask patients about their sleep-related symptoms, but we also should encourage patients to describe their symptoms as specifically as possible to gather a complete picture. To realize the goal of making screening sleep problems accessible and help clinicians more systematically improve patient care, we need healthcare system leaders to buy in to bring these screening tools into our EHR system.
What Are the Takeaways?
There is a connection between sleep, cardiovascular health, mental health and overall physical well-being. The impact of sleep on cardiovascular health is increasingly recognized, and the American Heart Association added sleep to its cardiovascular health checklist. A chronic illness, such as HF, may mediate psychological conditions, including anxiety and depression, which may further exacerbate sleep problems. More work needs to be done to promote sleep health and increase screening for sleep disorders in persons with HF and/or other cardiovascular conditions.
Additional Resources for Clinicians
- Read the AASM Position Statement on Apnea Test
- Learn about the Clinical Practice Guideline for Diagnostic Testing
The next time a patient tells you, "Oh, I have not slept well lately," you might ask, "Tell me more about the trouble you have with your sleep."
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