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Chapter 4

Psych Chapter 4 Study Guide

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Chapter 4 Study Guide Biological Rhythms What is the Biological rhythms also called? Circadian rhythms Biological rhythms: Natural variations in biological functions, hormonal activity, temperature, and sleep that typically cycle every 24 to 25 hours. Suprachiasmatic nucleus (SCN): An area of the hypothalamus that is located above the optic chiasm. What does the SCN do? Exerts the main control over biological rhythms. What is the SCN also referred to as? Why? Abiological clock; because damage to this area disrupts daily cycles in sleep and other biological functions. The Science of Sleep and Dreaming Sleep: Natural, periodically occurring state of rest characterized by reduced activity, lessened responsiveness to stimuli, and distinctive patterns of brain activity. REM Sleep: State of sleep characterized by rapid eye movements, and often associated with dreaming. NREM Sleep: Stages of sleep during which rapid eye movements typically do not occur. How frequently does dreaming occur during NREM sleep and REM sleep? Dreaming occurs most often in REM sleep. Measuring Stages of Sleep EEG (electroencephalogram): Measures brain waves EOG (electrooculogram): Measures movements of the eye EMG (electromyograph): Measures electrical activity in the muscles Characteristics of Waking and Sleep Cycles Beta waves: High-frequency waves What does the EEG reveal when we are awake and alert? Low-amplitude, high-frequency waves What do our brain waves show when we are relaxed and drowsy, just before falling asleep? An alpha rhythm of higher amplitude and slower frequency. Alpha waves: Higher amplitude and slower frequency What three things happen when we are relaxed and drowsy, just before falling asleep? 1. Breathing and temperature drops 2. Body temperature drops 3. Muscles relax Stage 1 Sleep: Light sleep that occurs just after dozing off, characterized by brain waves called theta waves. Stage 2 Sleep: Typically follows stage 1 sleep, characterized by brief bursts of brain activity called sleep spindles as well as K-complex responses to stimuli such as noises. Stage 3 Sleep: Typically follows stage 2 sleep, characterized by an EEG tracing 20 to 50% of which consists of delta waves- virtually no eye movements during stage 3 sleep. Stage 4 Sleep: Deepest level of sleep, characterized by an EEG tracing exceeding 50% delta waves and virtually no eye movements. The Sleep Cycle How long does it take to reach stage 4 sleep after first dozing off? Roughly 45 minutes How long do we remain in stage 4? What happens after this period of time? About 30-40 minutes; we gradually return to stage 3 and 2 to stage 1. When does the first REM cycle occur? When we reenter stage 1, about 90 minutes after falling asleep. When do we move through successive cycles during the night? Between the various phases of REM and NREM sleep. Changes in Sleep Patterns withAge Newborns: Sleep 16 hours per day with 50% spent in REM sleep. Adults (20s): Sleep about 8 hours with 20% s
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