Kalat Chap 9.1 - Chapter 9 Wakefulness and Sleep Rhythms of...

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Chapter 9 Wakefulness and Sleep
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2 Rhythms of Waking and Sleep Endogenous Circadian Rhythms Internal clock operating on ~24 hour cycle Regulates sleep/ wake cycle Regulates frequency of eating and drinking, body temp, secretion of hormones, volume of urination
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3 Rhythms of Waking and Sleep Circadian Rhythms Remain consistent despite lack of environmental cues indicating time of day Differs between people Function of age
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4 Rhythms of Waking and Sleep Experiments remove environmental cues as to time of day Results depend upon amount of light In bright light, rhythms faster; subjects have trouble sleeping In constant darkness, rhythms slower; people have difficulty waking
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5 Rhythms of Waking and Sleep Humans generate rhythm slightly longer than 24 hours with no external cues Most people can adjust to 23- or 25- hour day, but not to 22- or 28- hour day Bright light late in day can lengthen circadian rhythm
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6 Rhythms of Waking and Sleep Suprachiasmatic Nucleus (SCN) Part of hypothalamus Located above optic chiasm Controls rhythms of sleep and temperature Damage results in less consistent body rhythms no longer synchronized to environmental patterns of light and dark Influenced by genes Both sides can work independently
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7 Fig. 9-4, p. 269
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8 Rhythms of Waking and Sleep Single cell extracted from SCN continues to produce rhythmic pattern Cells communicate to sharpen rhythm
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9 Rhythms of Waking and Sleep Genetic Factors Period – produces protein Per Timeless – produces protein Tim Both proteins increase activity of neurons in SCN Mutations to Per result in abnormal circadian rhythms
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10 Fig. 9-5, p. 270
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11 Rhythms of Waking and Sleep Melatonin Released from pineal gland Secretion begins 2 to 3 hours before bedtime Resets biological clock through effects on receptors in SCN Taken in afternoon, can phase-advance internal clock and be used as sleep aid
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12 Rhythms of Waking and Sleep Zeitgeber Stimulus that resets circadian rhythms to external world Light Exercise Noise Meals Temperature
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13 Rhythms of Waking and Sleep Jet Lag Mismatch of internal circadian clock and external time Sleepiness during day, sleeplessness at night, impaired concentration Traveling west “phase-delays” Traveling east “phase-advances”
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14 Rhythms of Waking and Sleep Retinohypothalamic Path Direct connection from retina to SCN Allows light to reset SCN Originates in special population of ganglion cells that use melanopsin Respond directly to light and do not require input from rods or cones
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15 Stages And Brain Mechanisms Alpha waves at beginning of relaxation Stage 1 Sleep just begun EEG dominated by irregular, jagged, low voltage waves Brain activity declines
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16 Stages And Brain Mechanisms Stage 2 Sleep spindles K-complexes
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