KSU - PSYC 4410 - Class Notes - Week 8
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PSYC 4410CHAPTER 8—WAKEFULNESS AND SLEEP - Rhythms of Waking and Sleeping o Early belief— cycles of wakefulness and sleep dependent upon external stimuli o Curt Richter—1922 proposed that the body generates its own cycles of activity and
inactivity - Endogenous Circannual Rhythms o Some animals generate endogenous circannual rhythms, internal mechanisms that
operate on an annual or yearly cycle Example: birds migratory patterns; animals storing food for the winter o circANNUAL→ YEARLY - Endogenous Circadian Rhythms o All animals produce endogenous circadian rhythms, internal mechanisms that operate
on an approximately 24-hour cycle o circaDIAN → DAILY o includes our: sleep cycle; freq. of eating and drinking, body temp, hormone secretion,
urination and drug sensitivity - Setting and Resetting the Biological Clock o The purpose→ keep our internal workings in phase with the outside world o Circadian clock generates a rhythm slightly longer than 24 hours when it has no
external cue to set it o Resetting our circadian rhythms is sometimes necessary o Zeitgeber: German meaning “time giver”; refers to the stimulus that resets the
circadian rhythm Examples: sunlight, tides, exercise, meals, arousal of any kind, meals, temperature of
environment, and so on. Depression, irritability, and impaired job performance are effects of using something
other than sunlight as a zeitgeber - Jet Lag o Disruption of the circadian rhythms due to crossing time zones Stems from a mismatch of the internal circadian clock and external time Sleepiness during the day, sleeplessness at night, and impaired concentration o Traveling west “phase-delays” our circadian rhythms o Traveling east “phase-advances” our circadian rhythms→ more difficult flying east - Shift Work o Sleep duration depends on when one goes to sleep o Working at night does not reliably change the circadian rhythm o Even after long periods of working at night, people can still feel groggy, sleep poorly during
the day, and body temperature peaks while sleeping instead of while working o Better adjustment—sleep in a dark room at daytime + work in bright room at
nighttime - Morning People and Evening People o Cycles can differ between people—different patterns of wakefulness and alertness o Change as a function of age o Young children are morning people o Adolescents are often night people o As an adult, it partially depends upon genetics - Mechanisms of the Biological Clock o Mechanisms of the circadian rhythms: suprachiasmatic nucleus (SCN); genes that
produce certain proteins; melatonin levels o The Suprachiasmatic Nucleus (SCN): main control center of the circadian rhythms of sleep and temperature located above the optic chiasm and part of the hypothalamus damage to the SCN results in less consistent body rhythms that are no longer
synchronized to environmental patterns of light and dark o The Suprachiasmatic Nucleus (SCN) and the Circadian Rhythm genetically controlled, unlearned manner
Single cell extracted from the SCN + raised in tissue culture continues to produce action potential in a rhythmic pattern Various cells communicate with each other to sharpen the circadian rhythm o The Suprachiasmatic Nucleus (SCN) and the Retinohypothalamic Path Light resets SCN via a small branch of the optic nerve called the
retinohypothalamic path Travels directly from the retina to the SCN The retinohypothalamic path comes from a special population of ganglion cells that
have their own photopigment called melanopsin – The cells respond directly to light and do not require any input from the
rods or cones Two types of genes are responsible for generating the circadian rhythm – Period: produce proteins called PER – Timeless: produce proteins called TIM – PER and TIM proteins increase the activity of certain kinds of neurons in
the SCN that regulate sleep and waking – Mutations in the PER gene result in odd circadian rhythms or decreased alertness
if deprived of a good night’s sleep o Melatonin The SCN regulates waking and sleeping by controlling activity levels in other areas of
the brain The SCN regulates the pineal gland, an endocrine gland located posterior to the
thalamus The pineal gland secretes melatonin, a hormone that increases sleepiness Melatonin secretion usually begins two to three hours before bedtime Melatonin feeds back to reset the biological clock through its effects on
receptors in the SCN Melatonin taken in the afternoon can phase-advance the internal clock and
can be used as a sleep aid - Stages of Sleep and Brain Mechanisms o Sleep is a specialized state evolved to serve particular functions o What are the mechanisms for producing sleep? - Sleep o Sleep is a state that the brain actively produces o Characterized by a moderate decrease in brain activity and decreased response to
stimuli o Sleep differs from the following states: Coma, vegetative state, minimally conscious state,
and brain death - Interruptions of Consciousness o Coma: extended period of unconsciousness characterized by low brain activity that
remains fairly steady; person shows little response to stimuli o Vegetative state: person alternates between periods of sleep and moderate arousal
but no awareness of surrounding; some autonomic arousal to painful stimulus; no
purposeful activity/response to speech o Minimally conscious state: one stage higher than a vegetative state marked by occasional
brief periods of purposeful action and limited speech comprehension o Brain death: no sign of brain activity and no response to any stimulus - Stages of Sleep—EEG o The electroencephalograph (EEG) allowed researchers to discover that there are various
stages of sleep →comparison of brain activity at different times during sleep o A polysomnograph is a combination of EEG and eye-movement records o Relaxation and Stage 1 Sleep (sleep has just begun) Alpha waves are present when one begins a state of relaxation The EEG is dominated by irregular, jagged, and low voltage waves Brain activity begins to decline o Stage 2 Sleep Stage 2 sleep is characterized by the presence of: Sleep spindles: 12- to 14-Hz waves during a burst that lasts at least half a second
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School: Kennesaw State University
Department: Psychology
Course: Physiological Psychology
Professor: Corrine McNamara
Term: Fall 2018
Tags:
Name: 4410 CHAPTER EIGHT
Description: These notes cover material discussed in chapter eight including wakefulness and sleep.
Uploaded: 10/18/2018
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