week 8- sleep Flashcards
Behavioural definition of Sleep
- Eyes Shut (humans)
- Certain Postures
- Inactivity
- Reduced muscle tone
- Reduced responsiveness
Measures of Sleep
-Summated brain wave activity (EEG)
-Active eyes open wakefulness: beta activity (13-30 Hz) is present in the EEG record (desynchrony: low amplitude, high frequency waveforms)
-Eyes closed wakefulness: alpha activity (8-12 Hz) appears in the EEG record
With sleep EEG synchrony develops: (high amplitude, low frequency waveforms)
Eye movements (EOG)
Muscle tone (EMG)
stage 1 non rem sleep
slow rolling eyes
K complex more than 75- lasts more than a half a second
stage 2 non rem sleep
Spindle- 12-14 hz- half to2 seconds
k complex
stage 3 non rem sleep
More and more k complexes= delta waves 3-2 hertz
30 5 of epoch delta waves
stage 4 non rem sleep
50% delta waves
Non REM sleep
-Theta and delta activity, and K Complexes and Sleep Spindles are present in the EEG record
-Stages 1 and 2 (N1, N2)
-Stages 3 and 4: delta activity (synchronized)
-Termed slow-wave sleep (SWS or N3)
-Light, even respiration and regular Heart Rate
Muscle control is present (toss and turn)
-Cognitive Activity (thought like, rational)
Difficult to rouse from SWS
REM sleep
- EMG activity extremely low
- Presense of saw tooth waves-
- Presence of theta activity (desynchronized EEG pattern)
- Enhanced and variable respiration and blood pressure
- Rapid eye movements (REM)
- Pontine-Geniculate-Occipital (PGO) waves
- Loss of muscle tone (paralysis)
- Vivid, emotional dreams
- Signs of sexual arousal
- Assess impotence - functional vs organic
Mental Activity in Sleep
- Mental activity continues during sleep
- Dreams occur during SWS and REM sleep
- REM sleep is accompanied by high levels of blood flow in the visual association cortex but low levels in the inferior frontal cortex
- REM eye movements resemble those made when a person scans a visual image
- Nightmares can occur during stage 4 of SWS
Ontogenetic Development of Sleep
50% when we are born- active sleep
Rapidly reduces then stays constant
Structure of Sleep in the Elderly
Same 9- minute cycling but waking up or lighter sleep
Possible Functions of Sleep
Protection Energy Conservation Restoration Brain Body
Sleep Deprivation Studies
- Human sleep deprivation studies indicate that sleep deprivation can impair cognitive function
- Perceptual distortions and hallucinations as well as impaired ability to concentrate have been reported during sleep deprivation
- But sleep deprivation does not result in a physiological stress response nor does it interfere with normal bodily function
- Animal studies indicate drastic health consequences of sleep deprivation
- Rats that are forced to walk on rotating platform lose sleep
- Sleep deprived rats exhibited increased eating and activity and eventually became ill and died
Biological Rhythms
-Many of our behaviors display rhythmic variation
SWS/REM cycles last about 90 minutes
-Daily rest-activity cycle is about 90 minutes
Circadian rhythms (“about a day”)
-One cycle lasts about 24 hours (e.g. sleep-waking cycle)
-Light is an external cue that can set the circadian rhythm
-Monthly rhythms
-Menstrual cycle
-Seasonal rhythms
-Aggression, sexual activity in male deer
Adaptive Advantage of Biological Rhythms
- Biological rhythms ensure that physiological and behavioural processes occur at times they will be of the greatest benefit.
- In the case of humans, that sleep occurs during the dark phase when the lack of night vision would be disadvantages.
Suprachiasmatic Nucleus
-The suprachiasmatic nucleus (SCN) contains a biological clock that governs some circadian rhythms
SCN receives input from
melanopsin containing ganglion cells in the retina, a pathway that may account for the ability of light to reset the biological clock (zeitgeber function)
the intergeniculate leaflet of the lateral geniculate thalamic nucleus
This pathway may mediate the ability of other environmental stimuli to reset circadian rhythms (e.g. animals own activity)
SCN lesions disrupt circadian rhythms
SCN cells don’t require direct neural connections to control circadian rhythms, but may do using chemical signals