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Sleep. Internal Clock Circadian rhythm –Circum = about –Dies = day.

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Presentation on theme: "Sleep. Internal Clock Circadian rhythm –Circum = about –Dies = day."— Presentation transcript:

1 Sleep

2 Internal Clock Circadian rhythm –Circum = about –Dies = day

3 Activities that are governed by an internal clock Waking and sleeping Eating and drinking Body temperature Secretion of hormones Fig. 9.1

4 Where exactly is the biological clock?

5 Suprachiasmatic Nucleus (SCN) Figure 9.2 A sagittal view of the suprachiasmatic nucleus (SCN) and the pineal gland in the human brain Klein/Thorne: Biological Psychology © 2007 by Worth Publishers

6 SCN Controls the circadian rhythm Location –Hypothalamus –Just above the optic chiasm Damage to the SCN –Still sleep the same amount –But the daily rhythm is destroyed Affects sleep, release of hormones

7 Studying the human circadian rhythm Put healthy adults in a room with no indication of time of day –Body creates a rhythm that is about 25 hours long –Indicates that if not reset, biological clock is 25 hours long –Free-running rhythm Fig. 9.4

8 Studying the human circadian rhythm Zeitgebers –Reset the biological clock to 24 hours –Position of the sun, for example –Visual photoreceptor –Nonvisual photoreceptor (light-dark cycle) Retinohypothalamic tract – passes info from nonvisual photoreceptor to SCN

9 Phase-Sequence Problems Fig. 9.5 Fig. 9.6

10 Wakefulness Reticular activating system (RAS) –Hindbrain through midbrain –Arousal of the brain, alertness

11 How to study sleep? By using something called an electroencephalograph (EEG) Electro: electric signals Encephalo: brain Graph: Measure Attach electrodes to the scalp Figure 9.13 EEG patterns during waking and sleeping, and a typical night’s sleep Klein/Thorne: Biological Psychology © 2007 by Worth Publishers

12 Stages of Sleep Caveat: there are now 3 NREM stages (Stages 3 and 4 have been combined), but textbook was published prior to this recent change

13 Stages of Sleep Relaxed wakefulness –Alpha waves Stage 1 –Theta waves

14 Stages of Sleep Stage 2 –Sleep spindles –K-complexes

15 Stages of Sleep Stage 3 –Delta waves –Transition phase into Stage 4

16 Stages of Sleep Stage 4 –Delta waves Stages 3 and 4: slow wave sleep Controlled by the raphé nuclei, which contains serotonin  decreased serotonin, decreased NREM sleep

17 Stages of Sleep Rapid Eye Movement (REM) EEG similar to Stages 1 and 2

18 REM Sleep Also called “paradoxical sleep” –EEG waves similar to waking state –Difficult to awaken person Loss of core muscle tone

19 REM Sleep Commonly associated with dreaming But, dreaming can occur during non-REM (NREM) sleep stages (1 through 4) REM sleep is produced by the caudal reticular formation

20 Effects of REM Sleep Deprivation Irritability Concentration difficulty REM rebound

21 Things that affect REM Sleep Alcohol Sleeping pills REM rebound

22 Dreams

23 Table 9.2 Klein/Thorne: Biological Psychology © 2007 by Worth Publishers

24 Function of Sleep

25 A restorative function Growth Development of nervous system Replace neurotransmitters More active during day  need more sleep

26 Evolutionary Perspective According to this theory, how much an animal sleeps depends on –How much time it spends each day searching for food –How safe it is from predators

27 Evolutionary Perspective Cats and bats –Eat nutritious food –Are relatively safe –Sleep for long periods of time Herbivores (plant eaters) –Graze much of the day –Need to look out for predators –Sleep in short spurts

28 Learning and Memory Memory consolidation

29 Sleep Disorders

30 Insomnia –Older adults, women –Noise, discomfort –Anxiety, depression –Caffeine, alcohol –Sleep apnea

31 Sleep Disorders Hypersomnia –Sleepwalking Non-REM –Night terror Non-REM Different from nightmare –Bedwetting Non-REM Treatment: conditioning –Narcolepsy REM Cataplexy Sleep paralysis

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