the sleep cycle Flashcards
what are 3 triggers for sleep?
Diurnal patterning is key
Arousal levels
Learnt behaviour
3 main regions control arousal
Brainstem reticular formation
Thalamus – Reticular nuclei
ARAS (Ascending reticular activating system)
what is included in the brainstem reticular formation?
Spans the three brainstem regions
Complicated network of fibres
Heterogeneous matrix
Complex but not Random
Some defined nuclei
what is the thalamus ?
Multinucleate region in the diencephalon
the thalamus has nuclei involved in 2 features what are they ?
1.motar
2.sensation
how many hemispheres are in the thalamus?
Two hemispheres linked by the intra-thalamic adhesion.
what is the reticular nucleus involved in?
controlling flow through the thalamus.
what is ARAS(ascending reticular activating system)?
Fibres from RF acting on thalamus and cortex
what 5 functions is ARAS involved in?
Arousal
Motivation
Integration
Motor control
Autonomic control
what are 2 key transmitters controlling in arousal?
1.Histamine
2.acetylcholine
what do orexin and melatonin regulate?
sleep cycle pattern
orexin
hypothalamus
melatonin
pineal gland
what 4 disorders is included are orexin and melatonin impacted by?
1.jet-lag
2.narcolepsy
3.mood disorder
4.memory.
what are the 3 things in waking?
Metabolically demanding
Sympathetic activity
Muscle tone and power
what are the 3 things in non-rem sleep?
Metabolism low
Parasympathetic activity
Muscle tension and movement decrease
what are the 4 things in rapid eye movement (REM) sleep?
Paradoxical Sleep’
Metabolically demanding
Sympathetic activity
Atonia
what happens to the levels in wake state
noradrenaline, 5HT and histamine levels increase
what does the reticular system activate?
ACh innervation of reticular nuclei of thalamus. Ach ↑
what happens to GABA cells(non rem-sleep cells) in slow-wave sleep?
in hypothalamus act on tuberomammillary bodies
when gaba cells act on tuberomammilary bodies what happens to the histamine levels?
decrease
when histamine levels decreases in gaba cells what happens to the act input to the thalamus
it decreases and so does the sensory input which is in the resting state
what happens to the levels of NA, 5HT in rem state
decrease
Loss of NA and 5HT reduces inhibition of ACh
in rem sleep what happens to the input to the thalamus?
increases and Cortical activity increases, but motor outflow is kept low by activation of glycine pathways
what are the 3 stages of rem sleep?
Waking
Non-REM (NREM or N)
REM
what are the 3 stages of NREM?
Stage N1: drowsy
Stage N2: light sleep
Stage N3: deepest - Slow-Wave Sleep (SWS)
Dyssomina -sleep disorder
what are the 4 main groups
Insomnias - lack of sleep
Parasomnias - around sleep
Sleep apnoea - breathing stopping
Narcolepsy - spontaneous sleep onset
Insomnias
Inability to fall asleep or remain asleep for sufficient time
what are 5 causes of insomnia?
Lifestyle (learnt behaviour)
Circadian rhythm disruption (jet-lag)
Emotional Disturbances
Ageing
Children
what are the 2 treatments of insomnia?
Behavioural therapy
Pharmacological (short term only) – hypnotics*
what is parasomnia caused by?
around sleep
partial arousal from different stages of sleep
Little/no recall of episode – nightmares/RBD dreams are recalled
what are 2 forms of sleep apnoea?
1.central
2.obstructive
what are risk factors for sleep apnoea?
Neurological
Weight/Hypertension
Adenoid/tonsil size/polyps
Smoking/Drinking
what are the treatments of sleep apnoea?
Pharmacological agents generally ineffective
Weight/BP management
Orthodontic intervention
Continuous Positive Airway Pressure (CPAP)
Surgery*
what is narcolepsy characterised by?
Excessive daytime sleepiness
Sudden onset sleep
Cataplexy - usually emotionally triggered
Sleep paralysis/RLS
Hallucinations – hypnagogic/hypnapompic
Disrupted nocturnal sleep patterns
Automaton-like behaviour
what are the causes of narcolepsy?
Orexin
Genetic
what is the treatment of narcolepsy?
Stimulants* and routine
