Fractal cycles of sleep, a new aperiodic activity-based definition of sleep cycles.

Sleep cycles are defined as episodes of non-rapid eye movement (non-REM) sleep followed by an episode of REM sleep. Fractal or aperiodic neural activity is a well-established marker of arousal and sleep stages measured using electroencephalography. We introduce a new concept of 'fractal cycles' of sleep, defined as a time interval during which time series of fractal activity descend to their local minimum and ascend to the next local maximum.

Performance of questionnaires to predict sleep-disordered breathing in acute stroke patients.

Sleep-disordered breathing is common in stroke and may negatively affect its outcome. Screening for sleep-disordered breathing in this setting is of interest but poorly studied. We aimed to evaluate the performance of eight obstructive sleep apnea screening questionnaires to predict sleep-disordered breathing in acute stroke or transient ischaemic attack patients, and to assess the impact of stroke/transient ischaemic attack-specific factors on sleep-disordered breathing prediction.

Nocturnal Cardiac Arrhythmias in Heart Failure With Obstructive and Central Sleep Apnea.

Background: Both obstructive and central sleep apnea (CSA) may contribute to nocturnal cardiac arrhythmias (NCAs). Data are scarce regarding the prevalence of clinically important nocturnal atrial and ventricular arrythmias in patients with heart failure with reduced ejection fraction (HFrEF) and OSA or CSA.

Research Question: In a cohort of patients with HFrEF, how does the prevalence of NCA compare among those with OSA, CSA, and those with no to mild sleep apnea? Is the severity of OSA or CSA associated with atrial and ventricular NCAs?

Study Design And Methods: This cross-sectional analysis is an ancillary study of the Effect of Adaptive Servo Ventilation on Survival and Hospital Admissions in Heart Failure (ADVENT-HF) trial.