Sleep Flashcards
where do the inhibitory processes which causes sleep originate from ?
in the pons
does serotonin induce or inhibit sleep?
induce sleep
do serotonin levels increase during the day or at night?
at night
what area of the brain stem is thought to be closely associated with controlling state of consciousness ?
reticular formation
do people with depression have increased or decreased serotonin?
decreased
define sleep
= a condition of body and mind which typically recurs for several hours every night. State of unconsciousness from which an individual can be aroused by normal stimuli
does brain activity vary at night during sleep?
yes
are chemical/peptides released into the CSF when you are tired?
yes
is there a spectrum to being conscious ?
yes
- awake to being alert
what excitatory neurotransmitter is produced from the hypothalamus?
orexin
what is the function of orexin?
required for wakefulness
does orexin concentration increase or decrease during sleep?
decrease during sleep
what condition can be caused by low concentrations of orexin ?
narcolepsy
what occurs when the SCN (suprachiasmatic nuclei) of the hypothalamus is electrically stimulated ?
can promote sleep
what neurotransmitter does the SCN of the hypothalamus stimulate to be produced?
melatonin
what structure produces melatonin?
pineal gland
does melatonin make you feel alert or tired?
tired
does orexin make you feel alert or tired?
alert
what is the incidence of narcolepsy ?
1/2000
what areas does the reticular formation area communicate with?
thalamus
higher cortical areas
excitatory neurons in which system are released from sleep centres in the reticular formation?
ascending reticular activating system (ARAS)
when you become older, why do you become more sleepy?
- active cells become fatigued and signals fade.
- inhibitory signals from reticular formation dominate the balance
- there is a rapid progression into sleep state
what two ways could you assess the level of consciousness ?
- check speech pattern, reading and writing skills
2. EEG - ElectroEncepheloGram to check electrical activity
what two ways are EEG recordings analysed?
amplitude
frequency
Are the brain wave lengths long or short during sleep ?
long
Have the brain waves got a high or low amplitude when sleeping?
high
name the four main types of wave pattern in the brain
alpha
beta
theta
delta
when would the alpha brain activity wave be seen?
awake and relaxed
when would the beta brain activity wave be seen?
awake and alert
when would the theta brain activity wave be seen?
- during sleep
- during emotional stress
when would the delta brain activity wave be seen?
during deep sleep
describe what alpha waves look like
high frequency, high amplitude waves
describe what beta waves look like
even higher frequency than alpha waves, low amplitude asynchronous waves
describe what theta waves look like
low frequency waves which can vary enormously in amplitude
describe what delta waves look like
low frequency but high amplitude
how would you describe the 5 stages of the sleep cycle?
Sleep is cyclical, moving through S1-S2-S3-S4-S3-S2-REM-S2-S3-S4
what waves are seen in stage 1 of the sleep cycle ?
theta
- high amplitude
- low frequency
is stage 1 of sleep cycle deep or light sleep
light sleep
in which stage of the sleep cycle do eye movements stop
stage 2
sleep spindles are seen in stage 2.
what are sleep spindles?
bursts of rapid waves
what waves are seen in stage 3 ?
delta waves interspersed with short episodes of faster waves
- shorter episodes than stage 2
what waves are seen in stage 4?
only delta waves
in which two stages is it very difficult to arouse someone ?
stages 3 and 4
in which stages does sleep walking normally happen?
stages 3 and 4
what does REM sleep stand for?
rapid eye movement
in which stage do dreams occur?
REM sleep
what percentage of sleep occurs in stage REM?
25 %
what stages are classed as slow wave sleep?
stage 1-4
what stages are classed as fast wave sleep?
REM sleep
why is the REM stage of the sleep cycle sometimes referred to as paradoxical sleep?
EEG waves are desynchronized, high frequency, low amplitude, very like the awake state
what physiological changes does deep sleep cause for the body?
with decreased
- vascular tone (and therefore BP)
- respiratory and basal metabolic rate (hence drop in body temp.)
in the REM stage the eye muscles contract, but what prevents the other skeletal muscles from contracting?
inhibitory projections from Pons to spinal cord
what is the benefit of inhibiting the other skeletal muscles in the body?
prevents people acting out the dreams
REM sleep is dependant on what pathways in which areas?
dependent on cholinergic pathways within the reticular formation and their projections to the thalamus, hypothalamus and cortex
what drugs increase the time spent in REM sleep?
Anticholinesterases
what type of waves are seen in REM sleep stage?
beta waves
is it difficult or easy to arouse someone from REM sleep?
difficult
what happens when animals are deprived of sleep for a couple of weeks?
they die
what four changes do people who are sleep deprived demonstrate?
- Impairment of cognitive function
- Impairment of physical performance
- Sluggishness
- Irritability
state 6 factors which are improved with good sleep habits?
- Neuronal plasticity
- Learning and memory
- Cognition
- Clearance of waste products from CNS
- Conservation of whole body energy
- Immune function
by what age may REM sleep be absent?
80 yrs
is REM sleep associated with memory ?
yes
why does REM sleep help with memory?
REM sleep has beta waves so the brain is alert but the person is sleeping.
therefore the person can consolidate information in their brain and move information from short term to long term memory
why may elderly patients have a poorer memory in relation to their sleep?
older people have less REM sleep so don’t consolidate their memories during their sleep
define insomnia
chronic inability to obtain the necessary amount or quality of sleep to maintain adequate daytime behaviour
is insomnia common or rare?
common
- affects 33% of adults
what is the difference between chronic and temporary insomnia ?
chronic = no identifiable cause temporary = response to pain, bereavement, crisis
what two disorders in insomnia associated with?
depression
post traumatic stress disorder
what two drugs can depress REM sleep?
Benzodiazepines
Barbiturates
what stage of the sleep cycle do nightmares occur?
REM sleep
what stage does night terrors occur in ?
deep delta sleep
do people remember they have had night terrors ?
no
do nightmares occur early or late in the night?
late
do night terrors occur early or late in the night?
early
what is somnambulism ?
sleep walking
what stage does sleep walking occur in?
stage 4
- non REM sleep stage
why does sleep walking decrease with age?
because stage 4 decreases with age
do people remember sleep walking ?
no
what stage of sleep do patients with narcolepsy enter when they fall asleep?
REM sleep with little warning
what is circadian rhythm ?
sleep pattern oscillating every 24 hours
what structure controls circadian rhythm?
suprachiasmatic nucleus (SCN) of the hypothalamus
what external cues affect the the suprachiasmatic nucleus (SCN) of the hypothalamus?
light and dark cycle cues
do blind people have circadian rhythm?
yes
is orexin high during the day or during the night?
during the day
what is the function of orexin ?
wakes you up
what is the function of serotonin?
makes you sleepy
what is the function of melatonin?
makes you sleepy
do people who were born blind have auditory dreams?
yes
