Sleep and wakefulness Flashcards
Delta waves
deepest sleep <4Hz
Alpha and beta waves
awake
Alpha=8-13 Hz
Beta=14-30 Hz
Sleep state is characterized by which wave states?
Theta waves (4-7 Hz) Delta waves (<4Hz)
What are the three brain states?
Awake
NREM
REM
What is the alpha rhythm? Where in the brain would you see activity?
Eyes are open
Rapid eye movements
Normal muscle tone
See activity in the occipital region. this is the hallmark of wakefulness
What are the different stages of sleep, on the way to REM?
N1=light sleep
N2=filler sleep
N3: deep sleep-slow waves
REM sleep
Describe N1 sleep:
LIGHT SLEEP o Alpha drops out and replaced by theta activity o Vertex sharp waves o Central apneas o Slower eye movements
Describe N2 sleep:
o Continued theta slowing
FILLER SLEEP
o Sleep spindles: 13-14 hz in the beta range that are football shaped
o K complexes: Large amplitude/biphasic evoked by stimulation (noise). Hypothesized to keep us asleep despite stimuli
Describe N3 sleep:
Deep sleep o >20% slow wave activity o .5-2 Hz slow waves o >75uV amplitude slow waves (tall!) o Highest arousal threshold of sleep
Describe REM sleep
o Stage-1 like EEG
o Sawtooth waves= sharp theta waves
o Rapid eye movements
o Reticular activation – desynchronization
o Phasic and tonic movements
o Muscle atonia
o Cognitive activity mostly in occipital lobes
o PGO spikes
o Autonomic instability—irregularity in respiration, arrhythmias. Switching back and forth between sympathetic and parasympathetic tone
NREM and REM cycle every how many minutes?
90 minutes.
When does N3 predominate? When does REM predominate?
o N3 predominates in the first 1/3 of night
o REM predominates in the last 1/3 of night
What sleep state predominates overall usually?
We are in N2 50% of the time we are sleeping
Describe Non-Rem sleep
Decreased HR and BP Low O2, high CO2 and slow breathing Normal thermal regulation Reduced muscle tone Reduced CBF Reduced cognition
Describe REM sleep
Variable sympathetic activity (breathing, HR, BP)
Very low O2, high CO2, slow breathing
Minimal muscle tone
Poikilothermic: Variable body temperature
Increased CBF
Bizarre cognition
Describe fetal sleep–how many hours?
What percent is active sleep vs quiet sleep?
Feti sleep 16-18 hrs each day
50/50 activity. Adults only spend 25% of their sleep cycle in REM sleep
What happens to slow wave sleep as we age?
Slow decline in slow wave sleep
What are Zeitgebers?
External cues which help us regulate circadian rhythms
What is entrainment?
Adjustment of circadian to surrounding cues. Bright light in evening will cause a phase delay (ie teenagers watching TV at night will go to bed at 3AM and sleep till NOON)
What is free running?
Persistence of circadian rhythms during constant conditions of light or darkness.Absence of Zeitgebers
What nucleus is responsible for regulating circadian rhythms?
SCN
what happens when you ablate the SCN?
Loss of rhthmycity
what happens when you isolate the SCN?
Loss of zeitgeber response. Cannot incorporate external cues into circadian rhythm
What cues cause melatonin to be released? What does melatonin do?
Melatonin is induced by darkness. It helps to shift the phase of the cycle towards sleep.
