SLEEP
Defining sleeep
Physiological perspectiee
- A reiersible unconscious state
- Iniolies specifc brainwave paterns
- There’s sporadic eye movements
- There’s decreased muscle tone
- There’s a compensatory increase following sleep depriiaton
Behaiioural perspectiee
- You’re non-responsive to external stmuli
- You adopt a typical posture
- You occupy a sheltered site
- You sleep at least once every 24 hours
Circadian Rhythm
The body’s natural oscillaton over 24 hours.
Controlled by SCN in the hypothalamus in the brain stem (i.e. your biological clock)
SCN = suprachiasmatc nucleus. Sensitve to chanees in lieht.
Light triggers the SCN, which instructs the pineal eland to release melatonin (which induces a
feeling of sleepiness)
Babies and adolescents need the most amount of sleep.
Stages of sleeep
Sleep is comprised or NREM and REM sleep. Each stage has a distnct cyclic nature throughout the
night.
NREM has 4 stages.
When we’re awake, brain waies are low-amplitude and high frequency. Many neurons are fring
simultaneously.
When we’re in deep sleep, neurons are fring in synchronised bursts, so brain waies and low
frequency and hieh amplitude.
REM has distnct electrophysiology. rrequency and amplitude is quite similar to when awake, but
rapid eye moiements and marked decrease in muscle tone.
REM is a physiological state that allows for dreaming to occur.
, - Betae Wide awake. Small and fast.
- Alpha: Relaxed awareness (like meditaton). Slightly larger and slower.
- Theta. Drowsiness, daydreamine, frst staee of sleep. Larger and slower.
- Deepest stages of sleepe delta waies. Largest and slowest. When dreamine usually occurs.
runctons of Slow Waie Sleep (SWS)
Memory traces redistributed from hippocampal networks to neocortex (frontal lobe)
i.e. Memory traces are inteerated into larger neural networks
Weakly potentated synapses are eliminated. “Downscaline”e irreleiant info eliminated.
runctons of REM Sleep
Immediate Early Genes (IEGs) are expressed, leading to lone-term potentaton (strengthening) of
associatons / neural connectons
Sleep and Emoton
Emotonal memory processine (correlated with quality and quantty of REM sleep)
Fear conditoning / extncton
Emotonal regulaton
- Sleep depriiaton creates a bias towards negatie informaton
rear Conditoning / Extncton
Sleep (REM in partcular) helps extnct preiiously learned fears
During REM, the limbic system is very actve (amygdala, hippocampus)e emotonal processing
Sleep depriied people + emotonally negatie stmuli
- Greater amyedala reactvity
- Greater loss of functonal connectiity between the media prefrontal cortex and amygdala
(less moderaton of emotons)
- More connectiity between locus coeruleus (releases noradrenalin during emotonal
experiences) and amygdala higher reactiity
Positie stmuli more likely to be met with blunt responses.
Also tend to antcipate negatie stmuli more readily
Defining sleeep
Physiological perspectiee
- A reiersible unconscious state
- Iniolies specifc brainwave paterns
- There’s sporadic eye movements
- There’s decreased muscle tone
- There’s a compensatory increase following sleep depriiaton
Behaiioural perspectiee
- You’re non-responsive to external stmuli
- You adopt a typical posture
- You occupy a sheltered site
- You sleep at least once every 24 hours
Circadian Rhythm
The body’s natural oscillaton over 24 hours.
Controlled by SCN in the hypothalamus in the brain stem (i.e. your biological clock)
SCN = suprachiasmatc nucleus. Sensitve to chanees in lieht.
Light triggers the SCN, which instructs the pineal eland to release melatonin (which induces a
feeling of sleepiness)
Babies and adolescents need the most amount of sleep.
Stages of sleeep
Sleep is comprised or NREM and REM sleep. Each stage has a distnct cyclic nature throughout the
night.
NREM has 4 stages.
When we’re awake, brain waies are low-amplitude and high frequency. Many neurons are fring
simultaneously.
When we’re in deep sleep, neurons are fring in synchronised bursts, so brain waies and low
frequency and hieh amplitude.
REM has distnct electrophysiology. rrequency and amplitude is quite similar to when awake, but
rapid eye moiements and marked decrease in muscle tone.
REM is a physiological state that allows for dreaming to occur.
, - Betae Wide awake. Small and fast.
- Alpha: Relaxed awareness (like meditaton). Slightly larger and slower.
- Theta. Drowsiness, daydreamine, frst staee of sleep. Larger and slower.
- Deepest stages of sleepe delta waies. Largest and slowest. When dreamine usually occurs.
runctons of Slow Waie Sleep (SWS)
Memory traces redistributed from hippocampal networks to neocortex (frontal lobe)
i.e. Memory traces are inteerated into larger neural networks
Weakly potentated synapses are eliminated. “Downscaline”e irreleiant info eliminated.
runctons of REM Sleep
Immediate Early Genes (IEGs) are expressed, leading to lone-term potentaton (strengthening) of
associatons / neural connectons
Sleep and Emoton
Emotonal memory processine (correlated with quality and quantty of REM sleep)
Fear conditoning / extncton
Emotonal regulaton
- Sleep depriiaton creates a bias towards negatie informaton
rear Conditoning / Extncton
Sleep (REM in partcular) helps extnct preiiously learned fears
During REM, the limbic system is very actve (amygdala, hippocampus)e emotonal processing
Sleep depriied people + emotonally negatie stmuli
- Greater amyedala reactvity
- Greater loss of functonal connectiity between the media prefrontal cortex and amygdala
(less moderaton of emotons)
- More connectiity between locus coeruleus (releases noradrenalin during emotonal
experiences) and amygdala higher reactiity
Positie stmuli more likely to be met with blunt responses.
Also tend to antcipate negatie stmuli more readily
