Physiology of sleep Flashcards
(42 cards)
1
Q
Atigraphy
A
-used to quantify circadian sleep-wake patterns and detect movement disorders during sleep; uses a motion sensor
2
Q
Polysomnography
A
- includes EEG, EMG and EOG. ECG and other monitoring
- helps diagnosis and monitoring of sleep apnoea, narcolepsy, restless legs and REM behavioural disorder
3
Q
Sleep latency
A
-time from ‘lights out’ to sleep
4
Q
REM latency
A
- Time from sleep onset to first REM episode
- normally 90 mins in adults
5
Q
Non-REM latency
A
-Time from sleep onset to first Non-REM episode
6
Q
Sleep efficiency
A
(Total sleep time/total time in bed) x100
7
Q
Multiple sleep latency test
A
-used to assess daytime somnolence and daytime REM onset in narcolepsy
8
Q
Average length of sleep
A
7.5 hrs a night
sleep is made up of non-rapid eye movement and rapid eye movement phases
9
Q
NREM sleep
A
- 75% of adult sleep
- decreased muscle tone, respiration, temp and HR
- has 4 stages
- increased parasympathetic activity, abolition of tendon reflexes, upward ocular deviation with no or few movements
- reduced recall of dreams if woken
10
Q
Dreams
A
- dreaming occurs in all stages of sleep but the content varies
- in NREM sleep the dreams are ‘thought-like’ as thought the person is solving a problem
- in REM sleep the dreams may be illegocial and bizarre
11
Q
Stage 1 NREM sleep
A
- 5% sleep
- drowsy period
- when woken from this stage one denies being asleep
- shows low voltage theta activity, sharp V waves
12
Q
Stage 2 NREM sleep
A
- 45% sleep
- shows the development of sleep spindles and K complexes
13
Q
Stage 3 of NREM sleep
A
- 12 % sleep
- <50% delta waves
14
Q
Stage 4 NREM sleep
A
- 13% sleep
- shows >50% delta waves
- physiological functions are at the lowest
15
Q
REM sleep
A
- 25% sleep
- darting eye movements are noted despite other muscles being paralysed
- REM sleep is characterised by high level of brain activity and physiological activity similar to wakefulness
- EEG shows low voltage, mixed frequency activity similar to an awake state. Sawtooth waves also seen
- in a typical night, we cycle through 5 cycles of NREM/REM
- REM increases in length throughout the night
- increased sympathetic activitiy, increased blood flow to genitals, increased protein synthesis, maximal loss of muscle tone with occasional myotonic jerks
- vivid recall of dream if awaken
16
Q
REM sleep behavioural disorder
A
-muscle paralysis does not occur resulting in violent movements coinciding with brain activity
17
Q
Sleep spindles
A
- waves with upper alpha or lower beta frequency
- seen in many stages but mainly stage 2
- duration <1 second
- symmetric and obvious in the parasagittal regions
18
Q
K complexes
A
- large amplitude delta frequency waves, sometimes with a sharp apex
- occur throughout the brain but more prominent in the bifrontal regions
- mediated by thalamocortical circuitry
- occur when patient is partially aroused from sleep
- semiarousal follows brief noises
- runs of generalised rhythmic theta waves sometimes follow K-complexes- an arousal burst
19
Q
V-waves
A
- v-waves are sharp waves that occur during sleep
- they are largest and most evident at the vertex bilaterally and are usually symmetrical
- multiple V waves tend to occur especially during stage 2 sleep
- occur after sleep disturbances
20
Q
Suprachiasmatic nucleus
A
- master clock of the brain
- located in the anterior hypothalamus
- orchestrates circadian rhythms and uses signals from the retina
- in the absence of solar guidance, the 24 hour sleep-wake cycle will gradually increase to 26 hours- free-running
- pineal melatonin can also reset the SCN and promotes sleep in jet lag
21
Q
Ventrolateral preoptic nucleus
A
- VLPO
- sleep switch nucleus
- has projections to the ascending arousal system
- VLPO induces sleep by switching off the arousal system
- people with damage to the VLPO have chronic insomnia
22
Q
Waking up
A
- Monoaminergic system switches off the VLPO to wake people up
- negative feedback from the monoaminergic system
- arousal is then stablised by orexin (hypocretin) neurons in the hypothalamus
- orexin neurons reinforce arousal system
- patients with narcolepsy have fewer orexin neurons, leading to somnolence during the day
23
Q
Acetylcholine
A
-cell bodies in the midbrain-pons nuclei
-activation brings on REM sleep
REM on neurons
24
Q
Noradrenaline
A
- cell bodies in the locus coeruleus
- REM off neurons
- activation reduces REM sleep
25
Dopamine
- cell bodies in PAG
| - D2 possibly enhances REM sleep
26
Serotonin
- cell bodies in raphe nuclei
| - 5HT2 stimulation possibly maintains arousal
27
Histamine
- cell bodies in the tubermammillary nucleus
| - H1 stimulation possible maintains arousal
28
alcohol
- increases slow wave sleep but in chronic use, loss of slow wave sleeo
- reduce initial REM but increase second half REM
29
alcohol withdrawal
- loss of slow wave sleep
- increased REM
- increase REM rebound
30
Anxiety disorders
- increased stage 1 sleep (light sleep)
- reduced REM, normal REM latency
- reduced slow wave sleep
31
Benzos
- decrease sleep latency
- increase sleep time
- reduce stage 1 sleep
- increase stage 2 sleep
- reduce REM and slow wave sleep
- REM rebound on cessation
- prevent transition from lighter stage 2 sleep into deep, restorative (stage 3 and 4) sleep
32
Cannabis
- increase slow wave sleep
| - suppress REM
33
Carbamazepine
- increases slow wave sleep
| - suppresses REM and increases REM latency
34
Dementia
- increased sleep latency and fragmentation
| - reduced sleep time
35
Depression
- loss of slow wave sleep
- increased REM-leading to early wakening
- reduced REM latency
36
Lithium
- suppresses REM and increases REM latency
| - increases slow wave sleep
37
Opiates
- decrease slow wave sleep and REM
| - withdrawal REM bound
38
Schizophrenia
- inconsistent reduction in REM latency and slow wave sleep
| - antipsychotics have variable effects
39
SSRIs
- alerting due to 5HT2 stimulation
- may reduce REM latency
- variable effects of REM suppression
40
Stimulants
- reduced sleep time by decreasing both REM sleep and slow wave sleep
- REM rebound on cessation (except modafinil)
41
Tricyclics
- REM suppression (especially clomipramine)
| - increased slow wave sleep and stage 1 sleep
42
Z-hypnotics
- less effect on sleep architecture
| - zopiclone may increase slow wave sleep
