The vertebrobasilar arteries are the blood vessels in the back of the neck, next to the spinal cord, that supply the brainstem -- the portion of the brain that, among other things, is responsible for maintaining consciousness. A blockage of blood flow in the vertebrobasilar arteries can cause syncope.
1. NREM-a recurring sleep state during which rapid eye movements do not occur and dreaming does not occur; accounts for about 75% of normal sleep time. nonrapid eye movement, nonrapid eye movement sleep, NREM sleep, orthodox sleep. sleep, slumber-a natural and periodic state of rest during which consciousness of the world is suspended; he didn't get enough sleep last night; calm as a child in dreamless slumber. 1  Facebook.
To understand sleep deficiency, it helps to understand how sleep works and why it's important. The two basic types of sleep are rapid eye movement (REM) and non-REM. Non-REM sleep includes what is commonly known as deep sleep or slow wave sleep. Dreaming typically occurs during REM sleep. Generally, non-REM and REM sleep occur in a regular pattern of 3â5 cycles each night. Your ability to function and feel well while you're awake depends on whether you're getting enough total sleep and enough of each type of sleep.