-Non-rapid eye movement sleep is dreamless sleep. During NREM, the brain waves on the electroencephalographic (EEG) recording are typically slow and of high voltage, the breathing and heart rate are slow and regular, the blood pressure is low, and the sleeper is relatively still.
-NREM-2 occurs after NREM-1, an individual relaxes more fully and has about 20 minutes of NREM-2. It is characterized by its periodic sleep spindles, or bursts of rapid, rhythmic brain-wave activity. About half the night is spent in this phase.
