ECG, sleep and circadian rhythms Flashcards
Where do active inhibitory processes arise to cause sleep?
pons - reticular formation
Where does the reticular formation send its activity?
thalamus and higher cortical areas
What is the precursor of melatonin crucial for sleep production?
serotonin
Damage to the SCN causes what?
disrupts sleep-wake cycle
Where does melatonin release occur due to SCN activity?
pineal gland
What does the hypothalamus release for wakefulness?
orexin/hypocretic
When is orexin active and inactive?
active = awake
stop firing during sleep
What can a defect in orexin cause?
narcolepsy
2 main ways to assess consciousness levels
1 - behaviour, general alertness, speech etc
EEG
EEG frequency increases with what?
neuronal excitation
4 main types of EEG wave pattern
alpha, beta, theta, delta
Alpha wave - what state?
awake, relaxed
Alpha wave - EEG
high frequency, high amplitude
Beta wave - what state?
awake, alert
Beta wave - EEG
higher frequency, lower amplitude and asynchronous as waves cancel out
theta - what state?
stressed, emotional, children
Theta - EEG
low frequency, varied amplitude
Delta - what state and EEG
deep sleep
low frequency, high amplitude
Sleep cycle
1 - theta, eye moves, easily awoken 2 - eye moving stops, sleep spindles 3 - delta waves with spindles 4 - delta 5 - REM
What stage can REM sleep look like on an EEG?
1
Deep, slow wave sleep - physiological characteristics
reduced vascular tone and bp, decrease temperature and BMR and resp rate
Inhibitory projections from where in REM sleep inhibit skeletal muscles?
pons –> spinal cord
What muscles are not inhibited in REM sleep?
eye muscles
What does sleep support?
neuronal plasticity, cognition, memory, immune system
No sleep can lead to..
psychosis, irritability, sluggish, impairments
2 types of insomnia
primary, no underlying problem, chronic
acute, secondary to bereavement, pain etc
Night terrors - explain
children wake up in a shock with eyes open, not remembered the next morning
What stage of sleep does nightmares occur in?
REM
