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.
There are 4 stages to NREM sleep that need to occur before REM sleep begins. (The following stages are found in the Quick Series Guide to Healthy Sleep) STAGE 1: Light sleep, lasts about 10 minutes. During this time, you feel calm and experience sudden arm and leg movement. Your heart rate lowers and the eyes open without awareness. If you are awakened you feel in a state of âhalf-sleepâ. STAGE 2: Begins a sleep that lasts about 30 â 45 minutes. During this time there is lack of movement, you become oblivious to your surroundings. If you wake up during this time, you do not remember your dreams. STAGE 3: Brief time before Stage 4.