Notes problem 7
How much sleep do we need? two possible answers: 1. Sleep has health-promoting and
recuperative powers and suggests that people need as much sleep as they can get, the usual
prescription is 8 hours per night. 2. The other answer is that many of us sleep more than we actually
need to and are consequently sleep a big part of our life away.
Stages of sleep
Three standard psychophysiological measures of sleep:
- REM sleep (rapid eye movement sleep) during low voltage (fast waves) and activity in the neck
muscles. This was discovered with EEG,EOG and EMG machines and thus making them the three
standard measures of sleeping behaviour.
First-night phenomenon: the disturbance of sleep due to a new environment.
Four stages of sleep EEG:
when a person goes to sleep alpha begin to punctuate the low voltage, high frequency signal that is
similar but slower than that of alert wakefulness. There is a gradual increase in EEG voltage and a
decrease in EEG frequency as the person progresses from stage 1 to stage 2.
Stage 1: low voltage high frequency signal.
stage 2: slightly higher amplitude and a lower frequency, in addition it is punctuated by two
characteristic wave forms: K complexes and sleep spindles.
K complexes: each k complex is a single large negative wave followed by a single large positive wave.
Sleep spindle: a 1/2 second waxing and waning burst of 12 to 14 Hz waves. – caused by random
impulses and linked to the function: memory consolidation.
stage 3: defined by the occasional presence of delta waves, these are the largest and slowest waves
with a frequency of about 1 to 2 Hz.
stage 4: is defined by a predominance of delta waves. – largest and slowest waves
each night about 4 to 5 cycles.
The first stage is called REM sleep and all other stages were called nREM but now stage 3 and 4 are
called slow-wave sleep (SWS).
Once sleepers reach stage 4 EEG sleep, they stay there for a time and then they retreat back through
the stages of sleep to stage 1. However when we return to stage 1 the stage is suddenly marked by
striking’s of electromyographic and electrooculographic changes which cause REMs and a loss of
tone in the muscles of the body core.
After the first cycle of sleep EEG the rest of the night is spent going back and forth through these
stages.
correlations of REM sleep:
- loss of core muscle tone
- low amplitude, high frequency
- cerebral activity, such as blood flow and oxygen consumption, increases to waking levels in many
brain structures and in general increase in the variability of the autonomic nervous system activity
(for example: blood pressure, pulse and respiration).
- muscles of the extremities twitch.
- often some degree of penile erection in males.
REM sleep theory: rapid eye movement because we need oxygen in the cortex.
, REM sleep and dreaming
- All measures tested except for loss of tone in the core muscles suggested that REM sleep
episodes are charged by emotions.
- Theory: is REM sleep the physiological correlate of dreaming?
Support: 80% of the awakenings from REM sleep but only 7% of awakenings from nREM
sleep led to dreaming recall. people who don’t remember their dreams awaken during an
episode of nREM sleep.
Criticism: dreaming is much more prevalent during NREM sleep than first was assumed. Also
REM sleep and dreaming can be disassociated, for example antidepressants greatly reduce or
abolish REM sleep without affecting aspects of dream recall.
Testing common beliefs about dreaming
1. External stimuli become incorporated into their dreams. Study: water was sprayed on
volunteers after they had been in REM sleep for a few minutes and then awakened a few
seconds later. In 14 of the 33 cases the water was actually incorporated into the dream
report.
2. Dreams only last an instant. Research suggests that dreams run on ‘real time’. Study:
volunteers were awakened 5 or 15 minutes after the beginning of a REM episode and asked
to decide based on the duration of the events in their dreams whether they had been
dreaming for 5 or 15 minutes. They were correct in 92 of 111 cases.
3. Some people do not dream. These people have just as much REM sleep as others and they
also report dreams if they wake up during REM sleep, although they may wake up less often
in REM sleep than others do.
4. Penile erections are commonly assumed to be indicative of dreams with sexual content.
Erections are reported just as often when not dreaming about sex related things as when
they were dreaming about sex related stuff. due to the increase in blood flow in the body
during the increased cerebral activity.
5. Sleep talking and walking occur during REM sleep. Sleep talking has no special association
with REM sleep. It can occur during any stage but often occurs during the transition to
wakefulness. Sleep walking often occurs during the SWS stages and never occur during the
REM sleep stage when muscles tend to be totally relaxed.
Interpretation of dreams
Freud: dreams are triggered by unacceptable repressed wishes, often of a sexual nature. Manifest
dreams: the way we see the dreams disguised as our latent dreams which include the real meaning
of our dreams. Freuds idea was, to understand a person’s psychological problems is to expose the
meaning of their latent dreams by interpretation of their manifest dreams.
The modern theory about this is from Hobson and is called the activation synthesis theory. It is based
on observation that during REM sleep many brain stem circuits become active and bombard the
cerebral cortex with neural signals. The most important aspect of this theory is that the information
supplied to the cortex during REM sleep is largely random and that the resulting dream is the cortex’
effort to understand these random signals.
Clinical anatomical theory:
How much sleep do we need? two possible answers: 1. Sleep has health-promoting and
recuperative powers and suggests that people need as much sleep as they can get, the usual
prescription is 8 hours per night. 2. The other answer is that many of us sleep more than we actually
need to and are consequently sleep a big part of our life away.
Stages of sleep
Three standard psychophysiological measures of sleep:
- REM sleep (rapid eye movement sleep) during low voltage (fast waves) and activity in the neck
muscles. This was discovered with EEG,EOG and EMG machines and thus making them the three
standard measures of sleeping behaviour.
First-night phenomenon: the disturbance of sleep due to a new environment.
Four stages of sleep EEG:
when a person goes to sleep alpha begin to punctuate the low voltage, high frequency signal that is
similar but slower than that of alert wakefulness. There is a gradual increase in EEG voltage and a
decrease in EEG frequency as the person progresses from stage 1 to stage 2.
Stage 1: low voltage high frequency signal.
stage 2: slightly higher amplitude and a lower frequency, in addition it is punctuated by two
characteristic wave forms: K complexes and sleep spindles.
K complexes: each k complex is a single large negative wave followed by a single large positive wave.
Sleep spindle: a 1/2 second waxing and waning burst of 12 to 14 Hz waves. – caused by random
impulses and linked to the function: memory consolidation.
stage 3: defined by the occasional presence of delta waves, these are the largest and slowest waves
with a frequency of about 1 to 2 Hz.
stage 4: is defined by a predominance of delta waves. – largest and slowest waves
each night about 4 to 5 cycles.
The first stage is called REM sleep and all other stages were called nREM but now stage 3 and 4 are
called slow-wave sleep (SWS).
Once sleepers reach stage 4 EEG sleep, they stay there for a time and then they retreat back through
the stages of sleep to stage 1. However when we return to stage 1 the stage is suddenly marked by
striking’s of electromyographic and electrooculographic changes which cause REMs and a loss of
tone in the muscles of the body core.
After the first cycle of sleep EEG the rest of the night is spent going back and forth through these
stages.
correlations of REM sleep:
- loss of core muscle tone
- low amplitude, high frequency
- cerebral activity, such as blood flow and oxygen consumption, increases to waking levels in many
brain structures and in general increase in the variability of the autonomic nervous system activity
(for example: blood pressure, pulse and respiration).
- muscles of the extremities twitch.
- often some degree of penile erection in males.
REM sleep theory: rapid eye movement because we need oxygen in the cortex.
, REM sleep and dreaming
- All measures tested except for loss of tone in the core muscles suggested that REM sleep
episodes are charged by emotions.
- Theory: is REM sleep the physiological correlate of dreaming?
Support: 80% of the awakenings from REM sleep but only 7% of awakenings from nREM
sleep led to dreaming recall. people who don’t remember their dreams awaken during an
episode of nREM sleep.
Criticism: dreaming is much more prevalent during NREM sleep than first was assumed. Also
REM sleep and dreaming can be disassociated, for example antidepressants greatly reduce or
abolish REM sleep without affecting aspects of dream recall.
Testing common beliefs about dreaming
1. External stimuli become incorporated into their dreams. Study: water was sprayed on
volunteers after they had been in REM sleep for a few minutes and then awakened a few
seconds later. In 14 of the 33 cases the water was actually incorporated into the dream
report.
2. Dreams only last an instant. Research suggests that dreams run on ‘real time’. Study:
volunteers were awakened 5 or 15 minutes after the beginning of a REM episode and asked
to decide based on the duration of the events in their dreams whether they had been
dreaming for 5 or 15 minutes. They were correct in 92 of 111 cases.
3. Some people do not dream. These people have just as much REM sleep as others and they
also report dreams if they wake up during REM sleep, although they may wake up less often
in REM sleep than others do.
4. Penile erections are commonly assumed to be indicative of dreams with sexual content.
Erections are reported just as often when not dreaming about sex related things as when
they were dreaming about sex related stuff. due to the increase in blood flow in the body
during the increased cerebral activity.
5. Sleep talking and walking occur during REM sleep. Sleep talking has no special association
with REM sleep. It can occur during any stage but often occurs during the transition to
wakefulness. Sleep walking often occurs during the SWS stages and never occur during the
REM sleep stage when muscles tend to be totally relaxed.
Interpretation of dreams
Freud: dreams are triggered by unacceptable repressed wishes, often of a sexual nature. Manifest
dreams: the way we see the dreams disguised as our latent dreams which include the real meaning
of our dreams. Freuds idea was, to understand a person’s psychological problems is to expose the
meaning of their latent dreams by interpretation of their manifest dreams.
The modern theory about this is from Hobson and is called the activation synthesis theory. It is based
on observation that during REM sleep many brain stem circuits become active and bombard the
cerebral cortex with neural signals. The most important aspect of this theory is that the information
supplied to the cortex during REM sleep is largely random and that the resulting dream is the cortex’
effort to understand these random signals.
Clinical anatomical theory:
