In obstructive sleep apnea (OSA) and heart failure (HF), multiple events during sleep, including hypoxia, decreased stroke volume, and fluid build-up in the lungs, lead to increased sympathetic activation, which results in sleep disruption and poor sleep quality. However, the effects of poor sleep, which usually lead to symptoms of excessive daytime sleepiness, are counteracted by the constant increase in sympathetic activation that occurs in heart failure. This may explain the lack of reports of excessive daytime sleepiness in patients with both HF and OSA.