Sedatives and Hypnotics Flashcards
What is the optimum number of hours for a healthy sleep?
7-9 hours
What are the 2 main types of sleep?
- rapid eye movement (REM)
- non rapid eye movement (NRRM)
How long does each sleep cycle last?
90-120 minutes i.e. in a typical night there are 2-3 cycles
Describe the stages of the sleep cycle
- stage 1 – drowsiness, small wave frequency ~5% of sleep time
- stage 2 – asleep, theta waves with sleep spindles and K-complexes ~50% of sleep time
- stage 3 – delta waves, less sleep spindle ~5% of sleep time
- stage 4 – deepest stage of NREM, delta waves, hard to wake, GH released, slow wave sleep ~15% of sleep time
- REM – fast desynchronised brain wave activity, body effectively paralysed, dreaming most likely to occur ~25% of sleep time
How can human brain activity be measured?
electroencephalogram (EEG)
When does REM duration increase?
towards the ends of the night
What is memory consolidation?
when short-term memory is converted to long-term memory
What can one night of bad sleep cause?
an accumulation of toxic beta amyloid in the brain
Give examples of sleep disorders
- snoring
- obstructive sleep apnoea
- insomnia
What does GABA binding to its receptor cause?
hyperpolarisation
What does the GABA receptor consist of?
19 subunits
Where does GABA bind?
at the interface of the alpha and beta subunits
What are GABA α1 subunits involved in and where are they highly expressed?
sleep expressed in ventrolateral preoptic nucleus
What are GABA α2 and 3 subunits involved in and where are they highly expressed?
anxiety expressed in amygdala
What are sedatives and hypnotics?
a class of drugs used to induce and/or maintain sleep, e.g. benzodiazepines and non-benzodiazepines (Z-drugs)
What are the sleep and wake promoters in the hypothalamus?
- sleep - VLPO
- wake - TMN
What is the mechanism of action of benzodiazepines?
they enhance the action of GABA and bind at GABA receptors to increase the flow of chloride ions into the cell to slow or stop nerve impulses
What are therapeutic actions of benzodiazepines in short-term use?
- anxiolytic
- hypnotic
- myorelaxant
- anticonvulsant
- amnesia
What do benzodiazepines do?
increase frequency of channel opening and non-selectively bind to alpha subunits 1-6 to induce sedation, anxiolytic, muscle relaxation and alcohol potentiation actions
Give examples of benzodiazepines in order of increasing lengths of action
- midazolam (very short)
- temazepam (short)
- lorazepam (medium)
- diazepam (long)
What are side effects of benzodiazepines?
- sedation
- muscle relaxation
- drowsiness
- dizziness
- decreased alertness and concentration
- impairment of motor coordination
What are the adverse side effects of benzodiazepines?
- oversedation
- memory impairments
- depression
- tolerance
- dependence
What does oversedation cause?
‘hangover’ effects due to a tolerance developing over 1-2 weeks and symptoms include drowsiness, poor concentration, incoordination, muscle weakness, dizziness and mental confusion
What is memory impairment by benzodiazepines characterised by and when is it induced?
lack of coordination and attention used to relieve from the stress of catastrophic disasters
