The ups and downs of heart rate during sleep: a source of heterogeneity in individuals with obstructive sleep apnoea.
STUDY OBJECTIVES The heart rate (HR) of patients with obstructive sleep apnea (OSA) exhibits cyclical variation during sleep-disordered breathing (SDB), decreasing during apnoeas/hypopnoeas and increasing abruptly when air exchange resumes. It is not yet known whether this variation exceeds spontaneous HR variation dur...