Sleep Flashcards
What three techniques are used to monitor activity during sleep?
Which phase of sleeping shows similar patterns of being awake
Where is sleep spindle located
Electroencephalography (EEG)
Electromyography (EMG)
Electrooculography (EOG) (eye)
REM seems awake
Sleep spindle located in stage 2 non rem
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 and ready for action
EOG -muscle of eye activity
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 and 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?
approx 90mins
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?
Stems from where and up to where
Reticular activating system
From brainstem to hypothalamus, thalamus and cortex
HYPERSOMNIA
Subjective test for sleepiness
Hypersomnia, which refers to either excessive daytime sleepiness or excessive time spent sleeping, is a condition in which a person has trouble staying awake during the day.
Epworth Sleepiness scale
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 – excitatory + effect on RAS
Ventrolateral Preoptic Nucleus – promotes sleep - effect on RAS
NOTE: they have an antagonistic relationship
Describe the circadian synchronisation of the sleep-wake cycle.
The suprachiasmatic nucleus is responsible for synchronising the sleep-wake cycle with falling light level
It receives an input from the retina (not from the usual photogenic cells) and as light level falls the suprachiasmatic nucleus becomes more active
Describe the effect of the suprachiasmatic nucleus on the nuclei within the hypothalamus.
Falling light level –> increased activity of suprachiasmatic nucleus
This leads to activation of ventrolateral preoptic nucleus and 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 that it releases melatonin –sleepy
Melatonin adjusts various physiological processes in the body that fit with sleep
What are some consequences of sleep deprivation?
Categorise them into
- Psychiatric and neurological
- pure neurological
- somatic
Psychiatric and neurological:
– Sleepiness, irritability, stress, mood fluctuations, depression,
impulsivity, hallucinations
neurological:
– Impaired attention, memory, executive function
– Risk of errors and accidents
– Neurodegeneration (?)
Somatic: – Glucose intolerance – Reduced leptin/increased appetite – Impaired immunity – Increased risk of cardiovascular disease and cancer – Death
Describe three ways in which sleep is regulated after sleep deprivation.
Functions of sleep
Reduced latency of sleep onset (fall asleep faster. Sleep onset latency= speed of falling asleep)
Increased NREM sleep (sleep for longer)
Increased REM sleep (after selective REM sleep deprivation)
Restoration and recovery – but active individuals do not sleep more • Energy conservation – 10% drop in BMR – but lying still is just as effective • Predator avoidance – but why is sleep so complex? • Specific brain functions – memory consolidation, …
