SLEEP DISORDERS Flashcards
stage 1 of sleep
~5-10min
transition from awake to asleep (loss of muscle tone, easily aroused)
stage 2 of sleep
~20min
light sleep, movement stops, HR and body temp. decrease
stages 3 & 4 of sleep
~30min each
deep or slow wave sleep (restorative), essential for cognitive function and nervous system
stage 5 of sleep
REM (rapid eye movement)
increased brain activity, processing and consolidation of information and emotions
sleep architecture
stages 1-5 make up the sleep cycle lasting about 90min
cycle is repeated 5-6x a night
neurotransmitters in sleep
high neuronal activity in histaminergic, noradrenergic and serotonergic pathways during wakefulness - decreased during non-REM and almost stops during REM
GABA in sleep
inhibitory transmitter
induces relaxation and sleep
melatonin in sleep
released from pineal gland
regulates circadian rhythm
orexins in sleep
from hypothalamus regulate sleep-wake cycle
sleep disorders
characterised by disturbances of usual sleep patterns or behaviours that cause distress and impair daytime functioning
insomnia
- inability to get to sleep
- inability to stay asleep
- waking early
- unsatisfying sleep (e.g. still tired)
- sleep disturbance alongside significant daytime dysfunction
parasomnia
disturbance of arousal-sleep maintenance mechanisms (polysomnography PSG often required)
sleep apnoea
restriction of airflow
interrupts breathing (poor sleep quality)
narcolepsy
neurological disorder when the brain is unable to regulate the sleep-wake cycle
management of sleep disorders and insomnia
- treat underlying condition
- sleep hygiene
- psychological therapies (CBT)
- complementary therapies (herbal)
- medication to increase pain inhibition via GABA/BZ receptor OR decrease excitation by blocking 5-HT or histamine receptors
sleep hygiene
- maintain an environment conductive to sleep (decreased noise etc.)
- avoid caffeine/alcohol
- relaxation (avoid exercise later in day)
- bed time routines
- body awareness i.e. rest-activity cycle
how does medication help sleep disorders
medication (hypnotics e.g. BZP or Z drugs, melatonin, chlormethiazole) decrease time to sleep onset and episodes of walking, BUT get an increase in total sleep time - short term use only i.e. 6 weeks
what medication is best for when you can’t get to sleep
Z drugs:
zopiclone
zolpidem
what medication is best for maintaining sleep
benzos:
diazepam
Benzodiazepines and Z hypnotics moa
- bind to GABA A receptor and enhance inhibitory effect of GABA - activation of the GABA receptor leads to influx of Cl- ions into the neuron reduces its excitability - thereby reducing activity in the brain - sedation, induces sleep
what part of the sleep cycle do benzodiazepines act on
BZs suppress stage 4 (deep sleep) and decrease REM
what part of the sleep cycle do Z drugs act on
Z drugs decrease stage 1 but increase stage 2, little effect on 3,4 and REM
BZs kinetics
- rapidly absorbed from GI tract and extensively metabolised by oxidation in the liver - some active metabolites e.g. oxazepam
- long, medium and short-acting BZs based upon plasma half-life and duration of action
- substrates for several CYP enzymes - caution when co-prescribed with inhibitors or inducers
- additive or synergic effects with other psychotropic drugs - increase impairment of motor/intellectual function or worsen respiratory depression
various formulations for BZ kinetics
oral, IM, and IV for acute/rapid sedation (agitation/pre-operatively) and for emergency treatment of seizures
low water solubility so administered with solvents or as emulsion
