Lecture 9 Flashcards
What is sleep
A condition of body and mind which typically recurs for several hours per day, in which the eyes are closed, the postural muscles relaxed, and consciousness is practically suspended
How to tell is someone is asleep?
Why do we need different methods for measuring sleep
specific postures, inactivity, reduced responsiveness, rapidly reversible, eyes closed, behavioural preludes
sometimes it is not possible to do EEG on animals, especially when you go out of the primates range
The three E measures of sleep
Electroenchephalogram (EEG): Summated brain wave activity
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)
Electrooculogram (EOG): Eye movements
Electromyogram (EMG): Muscle tone
Describe EEG, EMG and EOG features for different stages of sleep
Awake - eye movements, Beta, alpha also occurs
Stage 1 drowsiness - eye movement slows, alpha disappear, theta appears - consicous
stage 2 light sleep - eye movement stops, sleep spindles and K complexes, theta wave
stage 3 deep sleep SWS - no eye movement, delta wave appears, sleep spindles and K complexes (due to neurons firing in synchrony), increase in amplitutde
stage 4 deep sleep SWS - no eye movement, delta wave, high amplitude
REM - rapid eye movement, sporadic muscle twitches little EMG, saw tooth wave, theta, desynchronized
in term of EMG, for resting wakefulness and NREM sleep, the muscle is relaxed and it shows on the graph, however, during REM, the muscle is very relaxed and the graph becomes super smooth (used to distinguish stage 1, wakefulness from REM
Features of 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, N3)
Light, even respiration and regular Heart Rate
Muscle tone is present (lower than wake)
Cognitive Activity (thought like, rational)
Difficult to rouse from SWS
Features of REM sleep
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, except breathing and eye muscles)
Vivid, emotional dreams
Signs of sexual arousal
CHECK THE SUMMARY OF SLEEP STAGES, IT’S A TABLE
basically another summary of features of eeg, emg and eog
CHECK
The structure of sleep over the night
Start with a lot of N-REM, and gradually stage 3-4 (sws) decreases over the night, REM increase
we also wake up several times during the night but we don’t know
Ontogenetic development of sleep
babies sleep for 16 hours a day and half are REM, during the first two years the amount of REM sleep drastically decreases
when you are old, it is harder to maintain sleep, you get about 4-6 hours not much REM at all
How is sleep controled
Process S - homeostatic
Process C - circadian factor
Describe homeostatic control of sleep
Evidence?
Regulatory process are activated to ensure that appropriate levels of sleep occur, including rebound effects
If sleep is reduced or disturbed negative consequences ensue.
The homeostatic process in sleep is reflected in SWS
Decrease in sws over the night thought to reflect the need for sws dissipating
What is circadian rhythm
not a good definition at all but
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 Circadian rhythms are endogenous (do not require input) suggesting the existence of an internal (biological) clock
Describe to me the 50 or so day of lock up experiment
Original version is that after setting people up with regular on and off of lights they are able to control their own schedule. However over the years, variations in flavour emerged such as dim lights, IV drops to keep people alive so they don’t rely on food…… lolol, you no gonna get be 2 do dis
The conclusion of the 50 or so day lock up experiment
Interpretations:
The sleep-wake cycle remains rhythmical, therefore the source of the rhythmicity must be internal.
The period of the internal clock must be greater than 24 hours.
In a normal environment, the 24-hour period must be the result of external factors.
Describe the two afctor theory (Borbely) - and how the graph would look like
Two basic processes underlie sleep regulation:
Homeostatic factor (Process S)
Circadian factor (Process C)
Process S is hypothesised to increase exponentially during wakefulness and decrease exponentially during sleep.
Process C is a sine wave function.
