9 Wakefulness and Sleep Flashcards
Rhythms that last about a day
Endogenous circadian rhythms
Waking and sleeping Eating and drinking Urination Secretion of hormones Sensitivity to drugs Body temperature
Behaviors subject to circadian rhythms
Light is critical for ______ rhythms
Resetting
Rhythm that occurs when no stimuli reset or alter it
Free-running rhythm
The stimulus that resets the circadian rhythm
“Time giver”
Zeitgeber
A disruption of circadian rhythms due to crossing time zones
A mismatch between internal circadian clock and external time
Jet lag
Phase delay
East to west
Phase advance
West to east
Stress elevated adrenal hormone called
Cortisol
______ have more accidents than day workers
Night workers
Part of the hypothalamus; provides the main control of the circadian rhythm for sleep and body temperature
The Superchiasmatic nucleus (SCN)
SCN is located just above
Optic chiasm
_______ start in small amounts early in the morning and increase during the day
Proteins
SCN regulates walking and sleeping by controlling activity levels in other brain areas, including:
Pineal gland
Gland releases hormone _____ - influences both circadian and circannual rhythms
Melatonin
Records average of the electrical potentials of the cells and fibers in the brain area nearest each electrode on the scalp
Electroencephalogram (EEG)
A combination of EEG and eye-movement records
Polysomnograph
Have frequency of 8 to 12 per sec.
Have characteristics of relaxation, not of all wakefulness
Alpha waves
EEG is dominated by irregular, jagged, low-voltage waves
Stage 1 sleep
Characterized by sleep spindles and K-complexes
Sleep spindle
Heart rate, breathing rate, and brain activity decrease; slow, large-amplitude waves become more common
Succeeding stages of sleep
More than half the record includes large waves of at least .5 sec duration
By stage 4
Stage 3&4 constitute
Slow-wave sleep
Slow waves indicated that neuronal activity is
Highly synchronized
REM sleep is _____ in some ways and ______ in other ways
Deep, light
REM and _________ sleep are synonymous
Paradoxical sleep
EEG shows irregular, low voltage fast waves that indicate increased neuronal activity
REM sleep
Postural muscles of body are more relaxed than in other stages
REM sleep
Part of reticular formation that contributes to cortical arousal
Maintains arousal during wakefulness and increases it in response to new or challenging tasks
Stimulation of area awakens sleeping individual or increases alertness in one already awake
Pontomesencephalon
Small structure in the pins that emits bursts of impulses in response to meaningful events, especially those that produce emotional arousal
Usually dormant while sleep
Locus coeruleus
Axons release _________ “adrenaline” widely throughout cortex
Norepinephrine
Anything that stimulates this area strengthens storage of recent memories and increases wakefulness
Locus coeruleus
________ has several axon pathways that influence arousal
Hypothalamus
One pathway releases _______- produces excitatory effects throughout brain
Histamine
The effect of antihistamine drugs
Allergy meds
Make you sleepy
Neurotransmitter released by pathway from hypothalamus- axons releasing orexin extend to basal forebrain and other areas and stimulate neurons responsible for wakefulness
Orexin or hypoctretin
Is necessary for staying awake
Orexin
Other pathways from lateral hypothalamus regulate cells in
Basal forebrain
Cells provide axons that extend throughout thalamus and cerebral cortex- some release acetyocholine
Basal forebrain
The role of GABA in sleep
Spontaneous firing rate
Important for decreasing body temperature
Spontaneously active neurons continue to fire - why do we remain unconscious ?
GABA suppresses the stimulation of neurons “inhibits”
Sleep walking & lucid dreaming mean that sleep can be
Local in the brain
Cells in the pons send messages that inhibit motor neurons that control large muscles
During REM sleep
What happens when most of the brain wakes up while the pons remain in REM?
Enable to move
During REM sleep:
Activity _______ in pons and limbic system
Increases
Activity _______ in primary visual cortex, motor cortex, and dorsolateral prefrontal cortex, but ______ in parts of parietal and temporal cortex
Decrease, increase
REM sleep associated with ____ ________ - high amplitude electrical potentials
PGO waves
During prolonged REM deprivation, _________ begin to emerge during stages 2-4, and even during wakefulness
PGO waves
Pons send messages to the _______ ______, which inhibits motor neurons that control the body’s large muscles
Prevents motor movements durning REM sleep
Spinal cord
REM sleep depends on relationship between ______ & _______
Serotonin & acetylcholine
Inadequate amount of sleep
Insomnia
Stress, noise, pain, dirt, uncomfortable temperatures, medications
Epilepsy, Parkinson’s disease, brain rumors, depression, anxiety, or other disorders
Causes of insomnia
Has trouble falling asleep at usual time
Rhythm is phase-delayed
Falls asleep easily but awakens early
Rhythm is phase-advanced
Impaired ability to breathe while sleeping
Sleep apnea
Condition characterized by frequent periods of sleepiness during the day
Narcolepsy
Attack of muscle weakness while person remains awake
Cataplexy
Inability to move while falling asleep or waking up
Sleep paralysis
Rhythm that prepares animal for seasonal changes
Endogenous circannual rhythm
Characterized by repeated involuntary movement of the legs and sometimes the arms
Occurs mostly during NREM sleep
Periodic limb movement disorder
People with this disorder move around vigorously during REM periods, apparently acting out their dreams
REM behavior disorder
Experiences of intense anxiety from which a person awakens screaming in terror
Night terrors
How does sleep enhance memory?
Electrical activity patterns observes during learning were observed again, except faster, during sleep
About ___% of sleep consists of REM
20
REM is important for _______ storage, especially for weakening the inappropriate connections
Memory
A dream represents the brains effort to make sense of sparse and disported information
Does its best to synthesize a story that makes sense
The Activation-Synthesis Hypothesis
Emphasized that dreams begin with arousing stimuli within brain combined with recent memories and any information the brain is receiving from the senses
The Clinico-Antaomical Hypothesis
characterized by a moderate decrease in brain activity and decreased response to stimuli
sleep
extended period of unconsciousness characterized by low brain activity that remains fairly steady
coma
person alternates between periods of sleep and moderate arousal but no awareness of surrounding
vegetative state
one stage higher than a vegetative state marked by occasional brief periods of purposeful action and limited speech comprehension
minimally conscious state
no sign of brain activity and no response to any stimulus
brain death