Sleep Flashcards
what are endogenous circadian rhythms
internal mechanisms that operate on an approx. 24 hr- cycle
T/F: humans reset and synchronize their circadian rhythms everyday
True
what are zeitgebers
stimulus that resets the circadian rhythms (sunlight, exercise, meals, arousal, temperature, tides)
how is out circadian rhythm affected when travelling west vs east
Travelling west phase-delays our rhythm
Travelling east phase-advances our circadian rhythm (more difficult)
why does working at night not reliably change the circadian rhythm
Because the stress hormones are higher
How do wakefulness change with age
Young children are morning people (waking earlier)
adolescents are often night people (sleeping later)
adults depends on genetics and environment
what are the main mechanisms of the biological clock
Suprachiasmatic Nucleus
Genes that produce certain proteins
melatonin
Where is the Suprachiasmatic Nucleus located
above the optic nerve and part of the hypothalamus
What happens when the SCN is damaged
less consistent body rhythms and no longer synchronized to environmental patterns
What are the main functions of the SCN (suprachiasmatic nucleus)
main control centre of the circadian rhythm (central pacemaker) of sleep and temperature
(really active in the day)
How are the neurons in the SCN unique and maintain the circadian rhythm
keeps their own rhythm and fires signals at their own rhythm.
extracted cells raised in culture produce action potential in a rhythmic pattern
SCN cells communicate with each other to sharpen the circadian rhytm
What is the retinohypothalamic path and what are its functions
a small branch of optic nerve and ganglion cells from the retina where it uses light to reset the SCN (photosensitive so can synchronize even tho you can’t see)
What photopigment does the retinohypothalamic path use to react to light
Melanopsin (does not require rods and cones)
describe the model for circadian timing system and pacemaking
light -> retina -> retinohypothalamic tract -> SCN pacemakers -> drives slave oscillators
what are slave oscillators
uses information from SCN to determine when to execute behaviours
each controls the rhythmic occurrence of one behaviour (body temp, hunger….)
what can SCN use to drive Slave oscillators
hormones, proteins, neurotransmitters
what are the two genes and corresponding proteins responsible for generating the circadian rhythms
Period: produces proteins PER
and
Timeless: produce proteins TIM
each expressed only in certain parts of the day
What do PER and TIM do
increase the activity of certain kinds of neurons in the SCN that regulate sleep and wake
how can mutations in PER affect the circadian rhythm
results in odd circadian rhythm or decreased alertness if deprived of a good nights sleep
Describe the interaction of mRNA with PER and TIM and its activity thoughout the day
PER and TIM slows down the SCN
during the day cells are actively making PER and TIM while the body is active, light degrade PER and TIM
during darker periods of the day PER and TIM concentration goes up and SCN slows down which activates the pineal gland producing more melatonin, cells relax and you get sleepy
as you are close to waking PER and TIM begin to diminish and degrade while asleep
What structure produces Melatonin and where is it located
Pineal Gland (slave oscillator)
posterior to the thalamus
how does the SCN affect the pineal gland
SCN inhibits the pineal gland reducing production of melatonin increasing wakefulness
why does phone screen keep you awake
ganglion cells are most sensitive to white and blue light, phone screen shines blue light which activates the ganglion cells and activates the SCN and keeps you awake
T/F the brain is inactive while asleep
False (its decrease in activity an decrease response to stimuli)
Describe a coma and causes of it
extended period of unconsciousness charactered by low brain activity that remains fairly steady, little response to stimuli, most commonly caused by brain injury
Describe a vegetative state
person alternates between periods of sleep and moderate arousal with not awareness of surrounding,
some autonomic arousal to pain stimuli
no purposeful activity/response to speech
Describe a minimally conscious state
a stage high than a vegetative state with occasional brief periods of purposeful action and limited speech comprehension
describe brain death
no sign of brain activity and no response to stimuli
What does an EEG do
allows researchers to compare bulk cortical activity at different times during sleep
What is a polysomnograph
combination of an EEG and eye-movement records
What is electromyogram
measures muscle movements and tone
Describe the 4 brain waves and what stages of wakefulness they are
Alpha Waves 8-12Hz relaxed and not asleep not intellectually engaged
Beta Waves 12 - 30Hz intellectually engaged (frontal and memory lobes are active)
Theta Waves 4-8Hz stage 1 or nREM 1 sleep slow waves with occasional spikes and can be poked awake
Delta Waves 1-4Hz nREM 3and nREM4 sleep very slow brain activity
describe the waking state and stage 1 of sleep using waves, eye movement and muscle movement
begins with beta waves (learning) or alpha (relaxed, awake) eye movement start slowing down, occasional muscle movements
stage 1 of sleep theta waves - irregular, jagged, low voltage waves
describe stage 2 of sleep using waves, eye movement and muscle movement
stage 2 slower theta waves - sleep spindles of 12 - 14 Hz during a first of at least half a second with a k complex which is a sharp wave associated with temporary inhibition of neuronal firing
describe stage 3 and 4 of sleep using waves, eye movement and muscle movement
stage 3 delta waves begin - slow wave sleep which is hard to wake up and where most of repair happens , large amplitude waves slowing heart rate, breathing rate, brain activity, high synchronized neuronal activity
stage 4 more delta wave presence beings with growth hormone release
still image dreams sometimes nightmares
describe paradoxical or REM sleep using waves, eye movement and muscle movement
rapid eye movement sleep, deep sleep, EEG waves are irregular, low-voltage, fast (like that and alpha)
muscle atonia (no movement, control), dreams occur
in What order of stages do people fall asleep in
progress through stages 1, 2, 3, 4 about after an hour experience the first REM episode and then the sequence is less organized and shows REM episode every 90 minutes
stages 3 and 4 earlier in the night
Longer REM as night progresses
brief waking period in the middle of the night
where is the reticular formation located
part of the midbrain extending from medulla to forebrain
what is the pontomesencephalon and where is it located
part of the reticular formation in the midbrain, contributes to cortical arousal (excitatory) releases glutamate and ACh Axons
where does Glutamate and ACh Axons extend to and what do they release
extends to the hypothalamus, thalamus, and basal forebrain, releasing acetylcholine, glutamate, or dopamine
what happens when you stimulate the pontomesencephalon
awakens sleeping individuals and increases alertness in those already awake
what would damage to the RF do
cause the person unable to wake up
what is the Locus Coeruleus and where is it located
a small structure in the pons
its axons release norepinephrine(adrenaline) arouses areas of the cortex and increases wakefulness
dormant while asleep
activates the cortex, hypothalamus and thalamus
how does the hypothalamus contribute to wakefulness
contains neurons that release histamines producing widespread excitatory effects throughout brain
lateral and posterior nuclei of hypothalamus release orexin
what does orexin do
peptide neurotransmitter sometimes called hypocretin
needed to stay awake (does not wake you up)
released into the basal forebrain (anterior and dorsal to hypothalamus) to stimulate neurons responsible for wakefulness and arousal
What neurotransmitter does the basal forebrain release
GABA and other axons release acetylcholine which is excitatory and increases arousal
what is the role of GABA
inhibitory neurotransmitter essential for sleep, hyperpolarizes neurons,
more GABA is produced as you sleep
decreases temperature and metabolic rate
hyper polarizes the thalamus (makes it so you can respond to senses)
decreases stimulation of neurons
what is the brain activity like during REM sleep
activity increase in pons, limbic system and visual cortex
activity decreases in motor cortex and dorsolateral prefrontal cortex (self-awareness)
neural activity is detected first in the pons then in the lateral geniculate of hypothalamus and then the occipital cortex
how does acetylcholine differ in other structure vs pons
in most structure it promotes wakefulness
in the pons it promotes REM
what happens when the Raphe Nucleus secretes serotonin
it terminates Rem
what does REM deprivation result in
a high density PGO waves during uninterrupted sleep (pons, geniculate, occipital cortex)
how does the body prevent motor movement during REM
cells in pons send GABA to spinal cord and inhibits the motor neurons
describe sleepwalking/somnambulism and its affects on the brain
awake in the motor cortex but deep sleep in others happens in stage 3 and 4 SWS
describe Lucid dreaming and its affects on the brain
dreaming but aware of being asleep and dreaming: high activity in frontal and temporal Cortex (important in self awareness)
describe sleep paralysis and its affects on the brain
the pons remaining in REM while other brain areas wake up: causes the inability to move
feels hard of breathing, and heavy weight on chest
describe insomnia and its affects on the brain
sleep disorder associated with lack of sleep -> hard time staying and falling asleep
caused by noise stress, pain, diet, medication, epilepsy, Parkinson’s, depression, anxiety, or dependence on pills alcohol and shifts in circadian rhythm
why is cannabis bad for sleep
marajuna hangover can be joyful at first but can induce insomnia later
describe sleep apnea and its affects on the brain
inability to breathe while asleep for prolonged period of time
can cause sleepiness during the day, impaired attentions, depression, heart problems
causes can be genetic, hormonal, old age, obesity, deterioration of the brain mechanism that control breathing
describe Narcolepsy and its affects on the brain
frequent periods of sleepiness where you just fall asleep whenever
occasional cataplexy (loss of muscle tone) triggered by strong emotions
sleep paralysis, hypnagogic hallucinations: dreamlike experiences
seems to be genetic
caused by lack of hypothalamic cells that produce and release orexin
stimulant drug like Ritalin increasing wakefulness and enhancing dopamine and norepinephrine
describe periodic limb movement disorders and its affects on the brain
repeated involuntary movement of legs and arms through the night
leg kicks once every 20-30 seconds for periods of minutes to hours
they are aware of doing it and can lead to insomnia
occurs during nREM
describe REM behaviour disorder and its affects on the brain
vigorous movement during REM sleep usually acting out dreams
motor neurons haven’t shutdown yet, inadequate GABA and other neurotransmitters ay be responsible
give SSRI’s
could see briefly during development
describe Night Terrors and its affects on the brain
intense anxiety from which a person awakes screaming in terror
occurs in nREM
most common in children (developmental)
happens in same period of night
should go away when they grow older
describe sleep walking and its affects on the brain
runs in families mostly occurs in young children, and in stage 3/4 sleep not associated with dreaming
what happens during animal hibernation
decrease in body temp to only slightly above that of environment
heart rate and brain activity drop to almost nothing
neuron cell bodies shrink and dendrites lose almost a fourth of their branches
