Presentation on theme: "1 Chapter 11 Sleep and Waking Digital Vision/Getty Images."— Presentation transcript:
1 Chapter 11 Sleep and Waking Digital Vision/Getty Images
2 Sleep Deprivation Trivia Peter Tripp stayed awake for 201 hours in 1959. Guinness Book of Records record is 18 days, 21 hours, 40 minutes. Sleep deprivation implicated in Three Mile Island, Exxon Valdez, Challenger and Bhopal disasters. Time Life Pictures/Getty Images
3 Examples of Biological Rhythms Seasonal migrations Mating seasons Menstruation Circadian rhythms: Daily rhythms “Circa” means around, “dia” means day
4 Zeitgebers: External Cues Help Set Circadian Rhythms “Zeit” means time in German. “Gebers” means givers. Internal clocks interact with zeitgebers. Light is an important human zeitgeber. Human “free-running” cycle is about 25 hours. Blind individuals and sailors serving on submarines may experience sleep problems.
5 Individual Variations “Larks” are morning people. “Owls” are night people. Many people are in between these extremes. Most adolescents are temporarily owls.
6 Results of Disruptions in Sleep Cycles More errors occur on evening and night shifts. Shift workers average 1.5 hours less sleep, and are more prone to sleep-related illnesses and psychological disorders. Jet lag Symptoms: fatigue, irritability Conflict between internal biological clock and external zeitgebers in new surroundings Adjustment to jet lag requires about 1 day per time zone crossed.
7 Adjustments to Phase Delays Are Easier than Phase Advances
Daylight Savings Requires Adjustment, Too April shift is a phase advance. analogous to eastward travel 7% increase in traffic accidents October shift is a phase delay. analogous to westward travel 7% decrease in traffic accidents
9 The Suprachiasmatic Nucleus in the Body’s Master Internal Clock “supra” – above (above optic chiasm) SCN is near: Hypothalamus Flow of visual info Retinohypothalamic pathway Axons from eyes going to hypothalamus Provides light info to hypothalamus to maintain circadian rhythms
10 SCN Activity and Light/Dark Cycles The SCN is active during the day in both diurnal and nocturnal animals. The SCN tells the animal whether it’s day or night, but not how to behave. Transplants of SCN establish donor rhythms in recipient animals. The SCN tells an animal the difference between night and day, not whether it’s time to sleep or be awake.
11 Origin of the Internal Clock Oscillations of protein production and degradation serves as the “ticking” of the internal clock (takes about 24 hours). Light may participate in the triggering of some of these protein fluctuations.
12 Protein Fluctuations and Fruit Fly Circadian Rhythms Proteins: - per - tim - Clock
13 The Biochemistry of Circadian Rhythms Cortisol release is highest in the morning and drops during the day. Glutamate Released by the retinohypothalamic tract during light Melatonin released only at night (by the retina and the pineal gland).
14 Seasonal Affective Disorder (SAD) Depression related to the season: 1.4% of Florida residents experience SAD. 9.7% of New Hampshire residents experience SAD. Icelanders may enjoy some genetic immunity. Serotonin levels normally drop in late fall through winter—people with SAD may experience too much of a drop. Light therapy uses lights of 2500 lux (normal indoor light is about 100 lux, sunlight is about 10,000 lux).
16 Stages of Waking and Sleeping Wakefulness is characterized by relatively desynchronized alpha and beta waves. Slow-wave sleep (SWS) is characterized by relatively synchronized theta and delta waves. 90–120 minute cycles characterize both sleep and wakefulness. Ultradian cycles
17 EEG During Wakefulness and Sleep Awake – alpha and beta waves Rapid-eye-movement sleep (REM) - active EEG, eye movements and muscular paralysis Stage 2 - Sleep spindles and K complexes Stages 3 and 4 - larger percentages of delta waves.
18 Sleep Patterns in a Typical Night The first 4 hours contain more SWS, especially Stages 3 and 4. The second 4 hours contain more REM. REM episodes occur approximately every 90–120 minutes.
20 Sleep Patterns Across the Lifespan REM sleep is more prevalent in infancy. Aging is associated with drops in overall sleep and proportion of SWS.
21 Dreaming Dreams occur during both SWS and REM. REM dreaming is more vivid, less logical, story-like and longer. Calvin Hall found that we usually dream about familiar places and routine activities, but unfamiliar people.
22 Theories of Dreams Hobson-McCarley: Dreams incorporate ongoing functions (e.g. vestibular activity) and/or environmental events (e.g. your alarm clock). Crick-Mitchison: Dreaming is a way to forget irrelevant information. Winson’s evolutionary approach: Animals integrate memories and experience while dreaming.
24 Reasons for Sleep Impossible to resist sleep indefinitely Fatal familial insomnia Sleep deprivation results Joint and muscle pain (SWS) Decreased reaction time Cognitive problems REM rebound
25 Reasons for Sleep Benefits of REM sleep Birds and mammals (except the echidna) show REM. REM increases after learning has occurred Brain development: REM more frequent in young Contradictory findings: Sometimes REM deprivation causes irritability Sometimes it improves mood in depressed patients