EEG. sleep and circadian rhythms Flashcards
Can a patient in coma be roused by normal stimuli?
No
Main difference between coma and just “asleep”
Where is the reticular formation found?
Brainstem
What are the actions of the reticular formation?
Contains arousal centres which are theorised to send activating signals to the thalamus and higher cortical areas
How is the pineal gland involved in the sleep cycle?
Inhibitory neurons in the scn are activated by light and inhibit the pineal gland. A lack of light therefore corresponds to increased melatonin and as a result, a sleepy feeling
What is the function of the suprachiasmatic nuclei (SCN)?
Controls the release of melatonin from the pineal gland
What is Orexin?
A stimulatory neurotransmitter released from the hypothalamus involved in the awake feeling
Inhibited by melatonin
What is Serotonin?
Precursor to melatonin
Drugs that block melatonin formation inhibit sleep
What does a lack of serotonin signalling indicate?
Depression
What is an EEG?
Recording of wave patterns which show the electrical activity of the brain
How many stages of the sleep cycle are there?
5
Describe stage 1 of the sleep cycle.
Non REM
Slow wave
Slow eye movement
Describe stage 2 of the sleep cycle.
Eye movements stops
Bursts of rapid waves called “sleep spindles”, otherwise slow
Describe stage 3 of the sleep cycle.
High amplitude
Low frequency
Describe stage 4 of the sleep cycle.
Exclusively delta waves
Describe the REM stage of the sleep cycle.
Dream time
What is insomnia?
Chronic inability to obtain the necessary amount or quality of sleep to maintain adequate daytime behaviour
Why are barbiturates not really used anymore?
Depress REM and delta sleep
What are some problems with treating insomnia using benzodiazepenes?
Highly addictive
Problematic on withdrawal
What is a benefit of benzodiazepenes?
Less effect on REM
What is a problem with using hypnotic sleep drugs?
They increase the chance of RTA’s
Describe some characters of night terrors
Dr Hogg
Occurs in deep delta sleep
Common in younger children
The child will not remember the episode on waking
What is somnabulism?
Eyes open, can see and preform reasonably complex tasks like preparing food
Occurs exclusively in non-REM sleep
No memory of episode when woken
What is narcolepsy?
Enter directly into REM sleep
Very dangerous
