| A | B |
|---|
| consciousness | a person's awareness of everything that is going on around him or her at any given moment |
| waking consciousness | state in which thoughts, feeling, and sensations are clear, organized, and the person feels alert |
| altered states of consciousness | state in which there is a shift in the quality or pattern of mental activity as compared to waking consciousness |
| circadian rhythm | a cycle of body rhythm that occurs over a 24-hour period (circa means around; diem means day) |
| hypothalamus | tiny section of the brain that influences the glandular system |
| suprachiasmatic nucleus | the tiny clock deep within the hypothalamus that tells people when to wake up and when to fall asleep/ tells pineal gland to secrete melatonin, which makes you feel sleepy |
| microsleeps | brief sidesteps into sleep lasting only a few seconds |
| sleep deprivation | any significant loss of sleep, resulting in problems in concentration and irritability |
| adaptive theory | theory of sleep proposing that animals and humans evolved sleep patterns to avoid predators by sleeping when predators are most active |
| restorative theory | theory of sleep proposing that sleep is necessary to the physical health of the body and serves to replenish chemicals and repair cellular damage |
| rapid eye movement (REM) | stage of sleep in which the eyes move rapidly under the eyelids and the person is typically experiencing a dream |
| NREM (non-REM sleep) | any of the stages of sleep that do not include REM |
| Non-REM Stage One | light sleep, may experience hypnagogic images (vivid, visual events), hypnic jerk (knees, legs, or whole body jerks) |
| Non-REM Stage Two | sleep spindles (brief bursts of activity only lasting a second or two) |
| Non-REM Stages Three and Four | delta waves pronounced |
| deep sleep | when 50%+ of waves are delta waves |
| Electroencephalograph (EEG) | allows scientists to see the brain wave activity as a person passes through the various stages of sleep and to determine what types of sleep the person has entered |
| alpha waves | brain waves that indicate a state of relaxation or light sleep |
| theta waves | brain waves indicating the early stages of sleep |
| delta waves | long, slow waves that indicate the deepest stage of sleep |
