Sleep Flashcards
What is consciousness
the level of awareness the individual has of their thoughts, feelings, perceptions and existence
2 types of consciousness
- normal waking consciousness
- altered state of consciousness
what is normal waking consciousness
an individual is awake and aware of thoughts, feelings, behaviours
e.g. being awake
what is altered state of consciousness
characteristics are different from normal waking consciousness, in terms of quality of experience and levels of awareness.
types of altered state of consciousness
Induced and naturally occurring
what is naturally occurring altered state of consciousness
a type of consciousness that that occurs without intervention.
e.g. sleep, and daydreaming
what is induced altered state of consciousness
a type of altered state of consciousness that occurs due to purposeful action or aid
e.g. meditation, alcohol, hypnosis
consciousness continuum
a visual representation of the different stages of consciousness that progress from lower levels of awareness to higher levels of awareness.
what is sleep
a regular and naturally occurring altered state if consciousness that involves loss of awareness and disengagement with internal and external stimuli
characteristics of sleep
- a reduced ability to control behaviour
- reduced control over thoughts e.g. we lack control over what we dream about
- less accurate understanding of time
- perseptual and cognitive disfunction
types of sleep
non-rapid eye movement (NREM)
rapid eye movement (REM)
what is NREM sleep
a type of sleep characterised by a lack of rapid eye movement and is subdivided into three stages.
(NREM 1,2,3)
what is REM sleep
a type of sleep characterised by rapid eye movement, high levels of brain activity, and low levels of physical activity
what is a sleep episode
the full duration of time spent asleep. it is made up of multiple repeated cycles of REM and NREM sleep
what is a sleep cycle
an approximately 90-minute-period that repeats during a sleep episode in which an individual progresses through stages of REM and NREM sleep
what is a hypnogram
a sleep graph that tracks the proportion of time spent in each stage of sleep, including awakenings, throughout a sleep episode
Characteristics of REM
- sleeper has a highly active brain and a less active body
- sleeper is virtually paralysed during REM sleep - most muscle movement is not possible
- relatively light stage of sleep; despite the muscle
paralysis, the brain is active and sleepers can be woken
fairly easily - Vivid dreaming tends to occur - sleeper frequently recalls dreams
- makes up approximately 20-25% of a sleep
episode for most age groups - The amount of time spent in REM sleep increases as the
sleep episode progresses, with the largest amount of REM
in the sleep cycle occurring immediately before waking
characteristics of NREM sleep
- sleeper has less active brain than normal waking consciousness.
- physical movement is possible - however, movement tends to decrease as NREM stages progress.
- Dreams can occur but they are often non-vivid - sleeper does not frequently recall dreams
- The amount of time spent in NREM sleep is highest during the
first half of a sleep episode. - makes up approximately 75-80% of a sleep episode
- NREM sleep tends to become shorter with each sleep cycle.
characteristics of NREM 1
- sleeper transitions from being awake into a light sleep
- hypnagogic state - feelings of floating or falling
- hypnic jerks/sudden jerks
- sleeper loses awareness of themselves and their surroundings but is still aware of faint sounds in the environment.
- sleeper can be easily woken
characteristics of NREM 2
- sleeper is still in relatively light sleep
- sleepers spend majority of their sleep time in NREM 2
- sleeper is considered “truly” asleep due to their brain waves
characteristics of NREM 3
- deepest sleep
- difficult to wake sleeper
- if sleeper is woken they are likely to be drowsy and disorientated
- sleep walking/talking is likely to occur
measures of consciousness (and sleep)
- the electroencephalograph (EEG)
- the electromyograph (EMG)
- the electro-oculograph (EOG)
- sleep diaries
- video monitoring
which measures of consciousness are objective
- the electroencephalograph (EEG)
- the electromyograph (EMG)
- the electro-oculograph (EOG)
advantages/disadvantages of objective measures of consciousness
provide reliable, unbiased, quantitative data that can indicate someone’s state of consciousness.
do not provide qualitative detail about the personal experience of sleep, such as thoughts or feelings.
changes in physiological responses may be due to factors other than a change in consciousness
which measures of consciousness are subjective
- sleep diaries
- video monitoring
are sleep measures always accurate
no
some techniques can be disruptive, invasive, or require
an individual to sleep in a sleep laboratory.
Changes to an individual’s regular sleep patterns, such as having to record their sleep or having electrodes attached
to their head, can influence the quality and quantity of an individual’s sleep.
what is an Electroencephalograph (EEG)
a device that detects, amplifies, and records the electrical
activity of the brain
how does an electroencephalograph work
a medical professional or researcher attaches electrodes to the
outside of a person’s head.
electrodes detect electrical impulses that are emitted by neurons when they communicate.
the impulses are presented as brain wave patterns.
different brain wave patterns correlate to different states of consciousness.
brain waves in REM sleep
beta
higher frequency and lower amplitude
brain waves in NREM 1
alpha
high frequency (lower than beta) and low amplitude (higher than beta)
brain waves in NREM 2
theta
medium frequency and medium amplitude
can show ‘sleep spindles’ - brief bursts of high frequency waves which sleep researchers identify as the point where a sleeper is truly asleep.
brain waves in NREM 3
delta
low frequency and high amplitude
Strengths of electroencephalography (EEG)
useful for sleep studies or diagnoses of patients with brain damage or a neurological or mental disorder
limitations of electroencephalography (EEG)
measures neural activity underneath a thick and hard skull and
thus is not entirely precise
does not identify functional and dysfunctional brain areas
what is electromyography (EMG)
a device that detects, amplifies, and records the electrical activity of the body’s muscles
how does electromyography work
electrodes are attached to the skin above the muscles under investigation, and the movement and tension of muscles are recorded.
REM sleep = EMG readings show low activity due to low levels
of physiological activity.
NREM sleep = EMG readings show medium/moderate activity, at first, and as stages progress, an EMG is likely to show lower activity as movement is less likely to occur
what is Electro-oculography (EOG)
a device that detects, amplifies, and records the electrical activity of the muscles responsible for eye movement.
how does electro-oculography work
electrodes are attached to the skin above the muscles responsible for eye movement.
REM sleep = EOG is likely to show high activity
NREM sleep = EOG is likely to show low activity.
what are sleep diaries
a record containing self reported descriptions from an individual about their sleeping periods, including an estimated time spent sleeping, and judgement they may have about the quality and nature of their sleep
what information can a sleep diary include
includes quantitative and qualitative info
- duration of sleep
- quality of sleep
- thoughts and feelings before going to sleep
- thoughts and feelings after waking up
- behaviours before going to sleep
- behaviours after waking up
- the number of times sleep was disrupted.
strengths of sleep diaries
they provide qualitative information and therefore are often
extensive in detail and description
limitations of sleep diaries
as the patient is responsible for collecting and reporting the information within a sleep diary, it is subjective and therefore may not be accurate.
What is video monitoring?
the use of camera and audio technologies to record an individual as they sleep.
strengths of video monitoring
provides data specific to the individual to track their sleeping and waking periods, their movements and activities when sleeping, and the sounds they make while sleeping
useful for individuals with sleep disorders, as their behaviors
during sleep can be observed
Limitations of video monitoring
video monitoring is subjective.
e.g. it may be unclear whether an individual seen to be getting out of bed during the night is awake or sleep-walking.
biological rhythms
repeated biological processes that are regulated by internal mechanisms
e.g. blood pressure, body temperature
two types involved in sleep: circadian and ultradian
circadian rhythms
biological and behavioral changes that occur as part of a cycle that lasts around 24 hours
e.g. sleep-wake cycle - involves biological changes
that occur over a 24-hour period
what is the sleep wake cycle
a 24-hour-cycle that is made up of time spent sleeping and time spent awake and alert
ultradian rhythms
biological and behavioural changes that occur in a cycle that lasts less than 24 hours
e.g. sleep cycle - involves changes in physiological activity that repeat in a cyclic manner in less than 24 hours
suprachiasmatic nucleus (SCN)
an area of the hypothalamus that is responsible for regulating
an individual’s sleep-wake patterns
acts as an internal body clock
- made up of 2 nuclei that have approximately 10,000 neurons each and are located above the optic chiasm