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a pa20023 > Sleep > Flashcards

Sleep Flashcards

1
Q

What is sleep

A
  1. A readily reversible state of reduced responsiveness to, and interaction with, the environment
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2
Q

What are the functions of sleep

A
  1. restorative - cortical recovery, tissue repair- Not a lot of evidence for growth of tissues and cells
  2. adaptation – protection from nocturnal predators
  3. metabolism/weight homeostasis
  4. memory consolidation and integration
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3
Q

How can you record sleep brain activity

A
  1. Electroencephalogram - EEG
  2. Records the activity of populations (many thousands) of neurons
  3. reveals synchrony of neuronal activity
  4. Stick electrode on scalp
  5. Record summed activity of nerves underneath the scalp
  6. Looks at synchrony of nerves
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4
Q

What does synchronous activity allow

A
  1. Synchronous activity gives rise to EEG rhythms
  2. frequency determines how fast neurones are firing
  3. amplitude (power) reflects number of neurones in synchrony
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5
Q

What are the different brain rhythms and functional states

A
  1. Delta rhythms < 4 Hz
  2. Theta rhythms – 4-7 Hz
  3. Alpha rhythms – 8-13 Hz
  4. Beta rhythms > 14 Hz
  5. Gamma- higher frequency
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6
Q

Describe state with delta rhythms

A
  1. deep dreamless sleep
  2. synchronized waves
  3. large amplitude, low frequency
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7
Q

Describe state with theta rhythms

A
  1. light sleep, dreaming, mental imagery, meditation, memory
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8
Q

Describe state with alpha rhythms

A
  1. conscious relaxation, mental visualisation
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9
Q

Describe state with beta rhythms

A
  1. awake, alert, concentration, cognition, motor activity, navigation
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10
Q

Describe state with gamma rhythms

A
  1. memory encoding and recall, attention, predictions, cognitive processing
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11
Q

Describe stages of sleep cycle

A
  1. Rapid eye movement (REM)
    - ~20 min
    - Dreaming
  2. Non rapid eye movement (NREM)
    - Stages I-4
    - 60-90 min
    - Repeat cycle 4-6 x
  3. Alternate periods of deep, non-rapid eye movement (non- REM) and REM sleep.
  4. Each cycle has shorter and shallower non-REM periods and longer REM periods
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12
Q

Describe the rhythms in the sleep cycle

A
  1. Awake
    - Dominated by alpha and beta rhythms
    - high frequency low amplitude
  2. Stage 1-4 Non-REM sleep
    - Go towards larger amplitude, low frequency
  3. REM sleep
    - Dominated by beta rhythms
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13
Q

Describe changes in REM sleep

A
  1. EEG like that of an active waking brain (“paradoxical sleep”)
  2. Oxygen consumption of brain is high
  3. Vivid dreaming
  4. Loss of skeletal muscle tone (atonia)
  5. Bursts of rapid eye movements
  6. Sympathetic activity predominates
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14
Q

What else changes in REM sleep

A
  1. Sympathetic activity dominates in REM sleep
  2. REM sleep is accompanied by changes in
  3. HR,
  4. respiration,
  5. local blood flow
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15
Q

Describe changes in NREM sleep

A
  1. Non-REM sleep is a rest period
  2. Muscle tension reduced
  3. Body temperature lowered
  4. Energy consumption lowered
  5. Increase in parasympathetic activity
  6. Brain rhythms slow (“slow wave sleep”)
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16
Q

What are important areas for control of sleep

A
  1. Reticular Activating system
    - brain stem lesions result in coma and sleep
    - brain stem stimulation induces wakefulness
  2. Thalamic stimulation induces sleep
  3. Thalamo-cortical inputs control sleep
17
Q

What system regulates wakefulness and alertness

A
  1. Ascending reticular activating system (RAS)- regulate wakefulness and alertness
  2. RAS– >Thalamus–>cortex
18
Q

What parts of the brain does the RAS regulate and what neurotransmitter do they effect

A
  1. Locus coeruleus – noradenaline
  2. Raphe nuclei – serotonin
  3. Brainstem/forebrain – acetylcholine
  4. Midbrain – histamine
  5. Increase Firing of these neurons = awakening
  6. Decrease Firing of these neurons = falling asleep
19
Q

Describe the ascending Reticular Activating System

A
  1. Cholinergic, serotonergic (5HT), noradrenergic neurones in RAS promote increased cortical and thalamic excitation
  2. Histamine neurones near hypothalamus also contribute excitation
  3. Orexin neurones in hypothalamus increase activity of RAS and histamine
  4. RAS/histamine inhibited by GABA/galanin neurones in hypothalamus
20
Q

What control of onset and offset of REM periods

A
  1. by brain stem neurons
  2. Cholinergic- increases firing as you go into REM
  3. serotoninergic and noradrenergic neurons increase firing as it goes into NREM
21
Q

RAS-thalamus-corticol interactions when you are awake

A
  1. RAS activates thalamus
  2. Thalamus generates non-thymic activity
  3. Cortex entrained into fast waking activity
    2) Asleep
22
Q

RAS-thalamus-corticol interactions when you are asleep

A
  1. RAS activity switched off
  2. Thalamus generates rhythmic activity
  3. Cortex entrained into low sleep rhythms
23
Q

List some sleep disorders

A
  1. Transient insomnia - noise, shift work, jet lag
  2. Short term insomnia - emotional issues, stress, anxiety
  3. Chronic insomnia - pain, depression, alcohol abuse, breathing disorder
  4. Fatal familial insomnia - rare prion disease
24
Q

What is a hypnotic

A
  1. A drug used to induce and maintain sleep
25
Q

What should use of hypnotics be

A
  1. Intermittent
  2. short term (< 2 weeks) if daytime impairment is severe
  3. tolerance may develop
  4. withdrawal syndromes can occur
  5. Treatment aims to shorten time to sleep, increase total duration of sleep, without suppressing sleep cycle and REM sleep
26
Q

What does blue light do

A
  1. Supresses production of melatonin
  2. Pineal gland can’t produce melatonin
  3. Melatonin can’t regulate your sleep cycle
  4. Lack of sleep
27
Q

What are some Benzodiazepine and related hypnotics

A
  1. Potentiate GABA inhibition by enhancing GABAA-receptors
  2. Benzodiazepines
  3. non-benzodiazepines
  4. barbiturates and barbiturate-like
28
Q

Give examples of Benzodiazepines and any problems

A
  1. Long acting e.g. nitrazepam, flurazepam
  2. Short acting e.g. loprazelam, temazepam, flunitrazepam
  3. problems with tolerance and dependence, and rebound insomnia
29
Q

Give examples of non-Benzodiazepines and any problems

A
  1. zolpidem, zopiclone, zaleplon
  2. may have sub-unit specificity – potentially less side effects
  3. different binding site to benzodiazepines
30
Q

Give examples of barbiturates and barbiturate-like and any problems

A
  1. phenobarbitone, methaqualone, meprobamate

2. rarely used now

31
Q

What are some other potential hypnotics

A
  1. Orexin antagonists
  2. Histamine H1 antagonists or inverse agonists
  3. Gamma-hydroxybutyrate
  4. Melatonin receptor agonists
32
Q

Describe orexin antagonists and give example

A
  1. suvorexant

2. orexin is involved in awakening

33
Q

Describe Histamine H1 antagonists or inverse agonists and give example

A
  1. over the counter sleep remedies

2. diphenhydramine, chlorpheniramine

34
Q

Describe Gamma-hydroxybutyrate and give example

A
  1. naturally occurring

2. may be a GABAB-agonist or metabolised to GABA

35
Q

Give example of Melatonin receptor agonists

A
  1. Melatonin (Circadin), ramelton
  2. may reset disturbed circadian rhythms
  3. jet lag, shift work patterns
36
Q

What is narcolepsy

A
  1. Pathological increase in sleep
  2. Sudden onset of sleep episodes and loss of motor control (cataplexy)
  3. May involve reduced numbers of orexin neurones – loss of RAS activation
37
Q

What is treatment for narcolepsy

A
  1. Stimulant drugs e.g. methylphenidate, modafinil, amphetamine-related
  2. Antidepressants - SSRIs, SNRIs, TCAs
  3. Sodium oxybate – (GHB)
  4. Orexin agonists?

a pa20023 (19 decks)

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