Sleep and hypnotics Flashcards
What is sleep?
A readily reversible state of reduced responsiveness to, and interaction with, the environment.
What are the functions of sleep?
Restoring - rest, relaxation and repair, adaptation (protection from nocturnal predators), energy conservation and memory consolidation and integration.
What is an EEG?
An electroencephalogram -it records the activity of populations of neurones. It reveals synchrony of neuronal activity.
What does frequency in an EEG show?
How fast neurones are firing.
What does amplitude power) reflect in an EEG?
The number of neurones that are in synchrony.
What are the 5 different frequencies representing brain rhythms and functional states?
Delta, theta, alpha, beta and gamma.
What is the delta brain rhythm?
Deep, dreamless sleep.
What is the theta brain rhythm?
Light sleep - dreaming, mental imagery, meditation and memory.
What is the alpha brain rhythm?
Conscious relaxation, mental visualisation.
What is the beta brain rhythm?
Awake, alert, concentration, cognition, motor activity and navigation.
What is the gamma brain rhythm?
Memory encoding and recall, attention, predictions and cognitive processing.
What is the difference between REM and non-REM?
non-REM is a deeper sleep that is not associated with dreaming, whereas REM is less of a deep sleep and is associated with dreams.
What is the pattern of REM and non-REM sleep?
There are alternate periods of REM and non-REM, with each cycle having shorter and shallower non-REM periods and longer REM periods.
How long are the cycles of REM?
20-40 minutes.
How long are cycles of non-REM?
60-90 minutes.
What is the reticular activating system?
It is an area responsible for regulating wakefulness and sleep-wake transitions.
What happens if the reticular activating system is lesioned?
Coma and sleep.
What happens if the reticular activating system is stimulated?
Wakefulness.
What happens if the thalamus is stimulated?
The patient will fall asleep.
What hormones/neurones contribute to sleep cycles?
Orexin neurones, cholingergic, serotonergic, noradrenergic, histamine neurones.
What are the interactions between RAS, thalamus and cortex in an awake state?
The RAS activates the thalamus and the thalamus generates non-rhythmic activity. The cortex is then entrained into fast waking activity.
What are the interactions between RAS, thalamus and cortex in an asleep state?
The RAS activity is switched off and the thalamus generates rhythmic activity, and the cortex is entrained into slow sleep rhythms.
How does the activity of brainstem neurons change from REM to non-REM sleep?
Non-REM sleep has decreased activity, whereas in REM sleep they are completely inactive (raphe nuclei and locus coeruleus).
What is transient insomnia?
Lack of sleep due to noise, shift work and jetlag.
What can cause short term insomnia?
Emotional issues, stress and anxiety.
What can cause chronic insomnia?
Pain, depression, alcohol abuse and breathing disorders.
What is fatal familial insomnia?
A rare prion disease that causes initially mild insomnia, that can develop severely and lead to physical and mental deterioration.
What are hypnotics?
Psychoactive drugs that induce sleep.
What is the action of hypnotics?
They potentiate GABA inhibition by enhancing GABAa receptors.
What is the name for common hypnotics?
Benzodiazepines.
What are the problems with hypnotics?
There are problems with tolerance and dependence and rebound insomnia.
What are the benefits of non-benzodiazepine hypnotics?
They may have subunit specificity, meaning there are potentially less side effects.
What are some other potential hypnotics?
Orexin antagonists, histamine H1 antagonists, gamma-hydroxybutyrate and melatonin receptor agonists.
What is narcolepsy?
A pathological increase in sleep. There is a sudden onset of sleep episodes and loss of motor control.
What are the treatments for narcolepsy?
Stimulant drugs such as modafinil and methylphenidate.
What are some examples of long acting benzodiazepines?
Nitraxepam, flurazepam.
What are some examples of short acting benzodiazepines?
Loprazelam, temazepam, flunitrazepam.
What are some problems with benzodiazepines?
Issues with tolerance and dependence and rebound insomnia.
What are some examples of non-benzodiazepine hypnotics?
Zolpidem, eszoplicone, zalepion.
What are some benefits of non-benzodiazepine hypnotics?
They may have less sub-unit specifity and may have less side effects.
What are some barbiturate and barbirutate-like hypnotics?
Phenobarbitone, methaqualone, meprobamate. They are rarely used now.
Give an example of an orexin antagonist.
Suvorexant.
Give an example of Histamine H1 antagonists.
Diphenhydramine, chlorpheniramine.
What is an example of a melatonin receptor agonist?
Melatonin, ramelton.
What is gamma-hydroxybutyrate?
A naturally occurring drug that may be a GABAB agonist or metabolised to GABA.
What can melatonin receptor agonists be used for?
Resetting disturbed circadian rhythms - due to jet lag or shift work patterns.
