Sleep Flashcards
What 3 techniques are used to monitor activity during sleep?
Electroencephalography (EEG) (brain)
Electromyography (EMG) (jaw)
Electrooculography (EOG) (eyes)
Describe the EEG and EMG activity in wakefulness.
EEG: fast brain rhythm – beta waves (~30 Hz)
EMG: reasonable amount of muscle tone because you are maintaining posture + ready for action
Describe the EEG, EMG and EOG activity in non-REM sleep.
Stage 1+2 Light sleep EEG: theta (4-8 Hz) waves – gradually becoming more + more drowsy EOG: NO eye movements EMG: muscle activity reduced considerably Stage 3+4 Very deep sleep EEG: Delta activity (< 4 Hz) EOG: minimal eye movement EMG: continued relaxation of muscles
Describe the EEG, EMG and EOG activity in REM sleep.
EEG: brain shifts abruptly back to fast rhythm (similar to wakefulness)
EOG: rapid eye movement
EMG: muscle activity at its lowest, subject is basically paralysed
How long is a normal sleep cycle?
90 minutes
Compare the relative amounts of NREM and REM sleep in a sleep cycle at the start of a night’s sleep and at the end.
Start of the night: more NREM sleep
End of the night: more REM sleep
Describe how heart rate and respiratory rate change during sleep.
SLOW during NREM
FAST during REM sleep
Which system is responsible for maintaining consciousness?
Reticular activating system
How does the reticular activating system control the activity of the cortex?
Either via direct connections
Or via indirect connections through the intralaminar nuclei of the thalamus
What are the two important nuclei in the hypothalamus that are responsible for influencing the reticular activating system and, hence, regulating the sleep-wake cycle?
Lateral Hypothalamus: promotes wakefulness
Ventrolateral Preoptic Nucleus: promotes sleep
(antagonistic relationship)
Describe the circadian synchronisation of the sleep-wake cycle.
Suprachiasmatic nucleus is responsible for synchronising the sleep-wake cycle with falling light level
Receives an input from the retina (not the usual photogenic cells) + as light level falls the suprachiasmatic nucleus becomes more active
Describe the effect of falling light level on the suprachiasmatic nucleus on the nuclei within the hypothalamus.
increased activity of suprachiasmatic nucleus
Leads to activation of ventrolateral preoptic nucleus + inhibition of lateral hypothalamus so you become sleepier
What other important projection does the suprachiasmatic nucleus have and what is the importance of this projection?
Projection to the pineal gland
Increase in suprachiasmatic nucleus activity leads to activation of pineal gland so it releases melatonin
Melatonin adjusts physiological processes in the body that fit with sleep
What are 7 psychiatric consequences of sleep deprivation?
Sleepiness irritability Stress Mood fluctuations Depression Impulsivity Hallucinations
Describe 3 ways in which sleep is regulated after sleep deprivation.
Reduced latency of sleep onset (fall asleep faster)
Increased NREM sleep (sleep for longer)
Increased REM sleep (after selective REM sleep deprivation)