Sleep Disturbances as a Risk Factor for Stroke

Abstract

Sleep, a vital process of human being, is carefully orchestrated by the brain and consists of cyclic transitions between rapid eye movement (REM) and non-REM (NREM) sleep. Autonomic tranquility during NREM sleep is characterized by vagal dominance and stable breathing, providing an opportunity for the cardiovascular-neural axis to restore homeostasis, in response to use, distress or fatigue inflicted during wakefulness. Abrupt irregular swings in sympathovagal balance during REM sleep act as phasic loads on the resting cardiovascular system. Any causes of sleep curtailment or fragmentation such as sleep restriction, sleep apnea, insomnia, periodic limb movements during sleep, and shift work, not only impair cardiovascular restoration but also impose a stress on the cardiovascular system. Sleep disturbances have been reported to play a role in the development of stroke and other cardiovascular disorders. This review aims to provide updated information on the role of abnormal sleep in the development of stroke, to discuss the implications of recent research findings, and to help both stroke clinicians and researchers understand the importance of identification and management of sleep pathology for stroke prevention and care.

Keywords: Cardiovascular system; Homeostasis; Sleep; Sleep apnea syndromes; Sleep initiation and maintenance disorders; Stroke.

Figure 1.

The mechanisms of sleep disturbances contributing to the development of stroke. PLMS, periodic limb movements during sleep; RLS, restless legs syndrome.

Figure 2.

Snapshot of recurrent respiratory events in obstructive sleep apnea. (A) Electroencephalography (EEG) plots for 30-second epoch. Respiratory arousal (closed arrowhead in panel A) occurs at the end of obstructive sleep apnea (closed arrowhead in panel B) in stage 2 rapid-eye-movement (REM) and non-REM sleep. The closed arrowheads on panel A and B indicate the same time. (B) Respiratory plots for three-minute epoch. Repetitive cessations of airflow (closed arrows) despite ongoing respiratory movements of the chest and abdominal belt are typical features. Obstructive sleep apnea is accompanied by decreased oxygen saturation (open arrows) and increased heart rate (open arrowheads). L, left; R, right; EOG, electrooculography; EMG, electromyography; EKG, electrocardiogram; SpO₂, peripheral oxygen saturation.

Figure 3.

Periodic limb movements during sleep. (A) Electroencephalography (EEG) plots for 30-second epoch. Arousal (arrowhead in panel A) is accompanied by periodic limb movement (arrowhead in panel B) during stage 2 rapid-eye-movement (REM) and non-REM sleep. The closed arrowheads in panels A and B indicate the same time. (B) Movement event plots for 2-minute epoch. Heart rate surges (open arrows) are associated with periodic brief electromyography (EMG) bursts in left or right tibialis anterior (close arrows). L, left; R, right; EOG, electrooculography; EKG, electrocardiogram; TA, tibialis anterior.