Wk 8.1 Sleep and Wakefulness Flashcards
What is the definition of sleep?
unconscious state from which a person can be aroused by sensory or other stimuli(Perodic reversible state)
What is the sleep epidemiology?
Ranks among the 3 important considerations in maintaining good health
Other two are:good nutrition stress management
62% of us population have sleeping problems
What is the function of sleep?
- Allows body to return to equilibrium
- Restoration – recover and prepare for next awake session
- Adaptation – hide from predators when we are most vulnerable or to conserve energy.
- REM sleep has been shown to aid in consolidation of memories
What does REM stand for and what happens during this stage?
Rapid Eye Movement Dreaming takes place
What are the stages of sleep
Stage 1 - wake- relax but going to sleep
Stage 2 first stage of sleep, k complexes and spindles waves on EEG means the person is asleep
Stage 3- less thalamic activity, neurons firing together
Stage 4- deep stage, 30 mins to get to this stage
What happens during deep sleep?
More the neurons are firing closer together
Bigger signal because the more the fire together, the more electrical waves
How do you read sleep cycle EEG?
High frequency and low amplitude for wake
Low frequency and high amplitude - for asleep
1.What is the % of sleep time in REM?
2. What happens in REM
3. What does REM cause
4. What does REM activate
1.Occupies 25% of total sleep time
2.Activity changes to REM approximately 4-5 times a night
3.Irregular heart rate and respiration
4.Melanin-concentrating neurons strongly active
How is sleep measured?
Electroencephalogram (EEG) electrode - attached to scalp to get information from the cortex
What regions are involved in sleep regulation?
Thalamus
Hypothalamus
Pineal gland
Locus Coeruleus
Dorsal raphe
An and po nucleus
Information on vebtrolateral preoptic nucleus?
-Contain GABAergic andGalanergic neurons
-Reduce monoamine arousalsystem during sleep
-Monoamine neurons inhibit its neurons
What are the two wakefulness pathways and what do they do?
-Acetylcholine Pathway Thalamocortical pathway= Activates thalamic relay neurons and reticular nucleus of thalamuscrucial for transmission of information to cerebral cortex
-Monoamine pathway Extrathalamic pathway = Activates neurons in the basal forebrain before activating cortex
What are the 2 acetylochloine cell gorups
-Pedunculo-pontine (PPT)
- Laterodorsal tegmental nuclei(LDT
What does monoaminergic neurons in the upper brainstem include.
- Locus ceruleus (NA)
- Raphe Nucleus (5HT) (dorsal andmedial)
- PAG and VTA (Dopamine)
- Tuberomamillary neurons(Histamine)- anti inhibits histamine leading to feeling sleepy
Which pathway is highly activated in REM sleep?
Acetylcholine Pathway
1.What is the flip flop sleep circuit?
2. How does it work?
- Two halves strongly inhibit each other and produce on or off switch
2.If either side is damaged or weakened= instability occurs in both sleep andwake states.
- When monoamines fire rapidly during wakefulness they inhibit the VLPO.
- When VLPO neurons fire rapidly during sleep they inhibit the discharge of the monoamine groups
What is the Regulation of sleep/wake cycles?
-Suprachiasmatic Nucleus of theHypothalamus = A Brain Clock
- 20,000 neurons and their circadian actibity is activated by light (Light is detected by eyes)
-Intact SCN produces rhythmic message:SCN cell firing rate varies with circadian rhythm
How does glycogen and Adeosine work?
Glycogen broken down to adenosine (Increased through out the day)
Adenosine increase causes need to sleep so It activated the vetro-laterial preoptic nucleus, blocks one of the sleep pathway the basal pathway
What does caffeine do to adeosine?
Caffeine blocks adeosine receptors and promotes alertness and arousal
What are the types of sleep disorders?
Insomnia
Narcolepsy
Restless leg syndrome
Sleep apnoea
What does insomia do?
Increase cerebal metabolism on PET
during sleep EEG - decreased delta and theta activity and increase in beta activity
Body temp is slighty higher
What are the different types of Insomnia?
-Sleep onset insomnia=Difficulty sleeping and longer sleep onset
-Sleep maintenance insomnia= difficulty staying asleep and awaking up
-Sleep offset insomnia= waking up early
-Nonrestorative sleep=Fatigue despite good sleep duration
What is Nacrolespy and key information?
-Neurological disorder- causes excessive daytime sleepiness
-Associated with Cataplexy
-Abdnormal REM sleep
-Neuronal loss of hypocretin neurons
What is Restless leg syndrome?
-Urge to move legs during sleep (arms, trunk orhead may be affected
