Sleep and Biological Rhythms Flashcards
What is sleep?
A behavior
Mostly unconscious state
We spend about 1/3 of our lives asleep
How do we measure sleep?
Electroencephalogram
Electrooculogram
Muscle tension
Stages of sleep
Waking
Non-rapid eye movement (NREM) sleep (1, 2, 3)
Rapid eye movement (REM) sleep
Waking
Alpha waves
Beta waves
Alpha waves
8-12 Hz
Usually when eyes are closed
Resting, little mental activity
Just before skilled actions
Beta waves
High frequency (13-30 Hz)
Irregular, desynchronous
Mostly frontal lobe
Alertness, attentiveness, active thinking
Dreaming
NREM 1
First fall asleep
Very light sleep
NREM 2
Light sleep where you can be easily aroused
NREM 3 (slow wave sleep)
Deeper stage of sleep
More difficult to rouse
May feel disoriented if woken from this stage
Rapid eye movement sleep
Rapid eye movement
On EEG looks similar to wakefulness
Stage 1 sleep
Theta waves
Theta waves
Low frequency (3.5-7.5 Hz)
Transition between waking and sleeping
Drowsiness, boredom
Hypnic jerks
Stage 2 sleep
Sleep spindles
K complexes
Sleep spindles
Short bursts of waves of 12-14 Hz
2-5 times a minute
Consolidation of memories, correlated with intelligence
K complexes
Sudden, sharp waveforms
Only found during this stage
Unsure of what they do
Once a minute
Stage 3 sleep
Delta waves
Delta waves
Very low frequency (less than 3.5 Hz)
High amplitude
“Slow wave sleep”
If woken up at this stage, will feel groggy
Brain activity increases in visual and auditory cortexes, decreases in thalamus and cerebellum
REM sleep
EEG becomes desynchronized, appears similar to waking state
Brain is very active with high oxygen consumption and blood flow
Increased limbic activity, but prefrontal is deactivated
Body mostly paralyzed, rapid eye movements, dreaming
If woken up, will remember dreams, alert and attentive
Easily aroused by relevant stimuli
Sleep across the lifespan
Early in life, sleep a lot (about half the time is REM sleep)
By adulthood, average 8 hours a night, 20% is REM sleep
REM sleep decreases with age
Functions of slow-wave sleep
Essential for survival
Allows brain to rest (decreased cerebral metabolic rate/blood flow)
Greater mental, but not physical, activity during the day increases slow wave sleep at night
Functions of REM sleep (several hypotheses)
Need to survive
Maybe helps with early brain development
Maybe for learning and memory consolidation
Neural control of sleep
Adenosine (a neuromodulator) may play a role in control of sleep
If awake too long, accumulation of adenosine –> cognitive/emotional effects of sleep deprivation
Caffeine is an adenosine antagonist
5 neurotransmitters that play a role in arousal
Acetylcholine
Norepinephrine
Serotonin
Histamine
Orexin
Acetylcholine
Involved in arousal of the cerebral cortex
2 groups: dorsal pons and basal forebrain
Agonists increase signs of cortical arousal
Most ach neurons elevated in REM sleep and when awake but decreased during slow-wave sleep
