Sleep Flashcards
1
Q
Disorders of Sleep
A
- Insomnia
- Sleep Apnea
- Narcolepsy
- REM sleep behaviour disorder
- Slow-wave sleep problems
- Fatal familial insomnia
2
Q
Characteristics of REM sleep
A
- Electroencephalography desynchrony (rapid, irregular waves)
- Lack of muscle tonus
- Rapid eye movements
- Penile erection or vaginal secretion
- Dreams
3
Q
Characteristics of Slow-Wave sleep
A
- Electroencephalography synchrony (slow waves)
- Moderate muscle tonus
- Slow or absent eye movements
- Lack of genital activity
4
Q
Functions of slow-wave sleep
A
- Slow-wave sleep deprivation affects cognitive abilities, especially sustained attention, but not physical abilities
- Cerebral metabolic rate and blood flow falls by about 75%.
- This coupled with people’s unresponsiveness, and confusion if awakened suggests cerebral cortex ‘shuts down’ during sleep.
5
Q
Functions of REM sleep.
A
- If deprived of REM sleep, you will have more REM sleep in the next sleep period (Rebound phenomenon).
- Highest proportion of REM sleep occurs during brain development
6
Q
Findings of studies of the effect of sleep on learning
A
- REM sleep facilitates consolidation of nondeclarative memories
- Slow-wave sleep facilitates consolidation of declarative memories
7
Q
Neurotransmitters that play a role in arousal.
A
Acetylcholine Norepinephrine Serotonin Histamine Orexin
8
Q
Describe the neural control of slow-wave sleep.
A
- controlled by 3 factors – homeostatic, allostatic, and circadian.
- Primary homeostatic factor – presence or absence of adenosine.
- Allostatic control is mediated by hormonal and neural responses to stressful situations
9
Q
So if a high level of activity in the arousal related neurons keeps us awake and a low level puts us to sleep, what controls the activity of these neurons?
A
- Inhibition of the arousal system is necessary for sleep
- Group of GABAnergic neurons in the ventrolateral preoptic area (vlPOA) become active and supress activity of arousal neurons.
10
Q
What is the sleep/wake flip-flop
A
- The flip-flop is on when the sleep-promoting neurons in the vlPOA are inhibited and the arousal neurons are active
- The flip-flop is off when the sleep-promoting neurons in the vlPOA are activated and the arousal neurons are inhibited
11
Q
Describe the effect of the orexinergic neurones in the sleep/wake flip-flop
A
- Orexinergic neurons help to stabilise the sleep/waking flip/flop
- Motivation to remain awake or events that disturb sleep activate the orexinergic neurons.
12
Q
What factors control the activity of the orexinergic neurons?
A
- Biological clock
- Hunger related signals activate them
- Satiety related signals inhibit them
- Orexinergic neurons receiving inhibitory input from the vlPOA because of a build-up of adenosine.
13
Q
Describe the Neural Control of REM Sleep
A
- Acetylcholinergic neurons also fire at a high rate in REM sleep
- There is a REM flip-flop
- REM-ON neurons are located in the pons
REM-OFF neurons are located in the midbrain
14
Q
Causes of insomnia
A
- Age - More common in older people
- Environmental factors
○ Electronic devices, noise, light–detrimental
○ White noise or other repetitive noise - beneficial - Physiology
○ Heightened activity in the reticular activating system - Circadian rhythms
- Medical conditions and medications
15
Q
Treatment of insomnia
A
- drugs, mindfulness and CBT.
16
Q
What is sleep apnea
A
- Form of insomnia – the inability to sleep and breathe at the same time
- Build of carbon dioxide in the blood stimulates chemoreceptors
- Disrupts sleep affecting daytime functioning
- If caused by obstruction can be corrected surgically or relieved by pressurised air that keeps the airway open
17
Q
Narcolepsy symptoms
A
- Sleep attack – overwhelming urge to sleep
- Cataplexy – muscular paralysis of REM sleep while awake
○ Varying degrees of muscle weakness
○ Can become completely paralyzed while conscious
○ Generally occurs when the person feels strong emotions or by sudden physical effort. - Sleep paralysis
○ REM muscular paralysis just before the onset of sleep or upon waking - Hypnagogic hallucinations
○ dreaming while awake and paralysed
○ can very realistic and terrifying.
18
Q
Causes of Narcolepsy
A
- Hereditary element
- Environmental factors play a role but are unknown
- Orexinergic neurons are attacked by the immune system, usually in adolescence
19
Q
Treatments of Narcolepsy
A
- Sleep attacks diminished with stimulants e.g methylphenidate (Ritalin)
- REM sleep phenomenon (cataplexy, sleep paralysis and hypagogic hallucinations) treated with antidepressant drugs
- Most common current treatments are modafanil and/or sodium oxybate (GHB; gamma hydroxybutyric acid), both stimulant drugs
20
Q
What is REM Sleep Behaviour Disorder
A
- Neurodegenerative disorder with a genetic component
- Failure to exhibit paralysis during REM sleep
- Acting out dreams
21
Q
Name some slow-wave sleep problems
A
- Sleepwalking (Somnambulism)
- Night terrors (pavor nocturnus)
- Bedwetting (nocturnalenuresis)
22
Q
What is Fatal Familial Insomnia
A
- Neurodegenerative condition
- Prion disease - caused by build up of abnormal prion proteins which are resistant to being broken down by enzymes = accumulation = damage to brain
- Damage to the thalamus
- Initially presents with insomnia and very vivid dreams when the person finally manages to sleep.
- Psychiatric complications – panic attacks, cognitive deficits, paranoia and phobias
- As the disease progresses it affects the autonomic nervous system (e.g. elevated blood pressure) and coordination (ataxia)
- EEG shows disturbances and reductions in sleep spindles and K complexes
- Disappearance of slow-wave sleep and only brief periods of REM sleep
- Ultimately inability to voluntarily move or speak (akinetic mutism), coma, and death.
