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
BZs as hypnotics
- induces sleep within 30 min (stages 1-3)
- residual effect likely, esp. with nitrazepam - caution in elderly
- driving offence - all BZs can impair driving ability but esp. clonazepam, diazepam and lorazepam
mild side effects of BZs
irritability
tremor
headache
nausea
moderate side effects of BZs
flu-like symptoms
decreased appetite
abnormal sensation of movement
affect driving performance
severe side effects of BZs
seizures
psychosis
amnesia
blurred vision
respiratory depression (IV route)
prescribing for withdrawal/cessation
- short-acting benzos tend to be more problematic
- to withdraw or stop - best to convert to diazepam and then gradually reduce by 1/8th or 1/6th of total daily dose every fortnight/week - over 6-12 months depending on symptoms
Z drugs - zopiclone, zolpidem, zaleplon
- alternative to BZs - lower risk of dependence/tolerance and abuse
- agonist at a1 subunit of GABA receptor (increased GABA mediated Cl- influx into the cell = inhibits neurotransmission)
- rapid onset and relatively short duration - decreased hangover effect, cognition function etc.
side effects of Z drugs
metallic taste (mainly zopiclone)
GI disturbance
dizziness
headache
OTC management of sleep
sedative antihistamines (diphenhydramine, promethazine)
OR
herbal products (lavender, CBD/cannabidiols)
for short term use only
antihistamines for sleep management
- only those that can cross the BBB - i.e. antagonists at the H1 receptor thereby causing sedation
- primarily used in children
- promethazine (5-10mg at night) however has a long half-life but low abuse potential
- diphenhydramine (25-50mg at night) increased potential for abuse - affects cognitive function
melatonin for sleep management
- natural hormone produced by the pineal gland regulating circadian rhythm of sleep i.e. stimulated by nightfall
- promotes sleep initiation - resets the ciradian clock
- agonist at M1,M2 and M3 receptors
- efficacy for primary insomnia is poor, better for jet lag
- relatively short duration of action, rapidly excreted (half-life is 30-60min)
