Chapter 6b Flashcards
Measuring sleep
Measuring sleep:same for consciousness due to the changes that occur being similar, can be gathered is through analysing the objective physiological changes that occur during sleep or exploring qualitative information about changes that occur during sleep.
• the electroencephalograph (EEG)
• the electromyograph (EMG)
• the electro-oculograph (EOG)
• sleep diaries
• video monitoring.
Objective sleep measured
EEGs, EMGs, and EOGs are considered to be objective physiological measures. This means that they provide reliable, unbiased, quantitative data that can indicate someone’s state of consciousness. However, they do not provide qualitative detail (thoughts or feelings). “, lack validity at times.
Subjective sleep measures
In comparison, sleep diaries and video monitoring are considered to be subjective measures. This means that information is provided by an individual and is related to their personal experiences. In this way, subjective measures do not provide a direct observation and the accuracy and reliability of such measures can be limited can provide both qualitative and quantitative data.
Measuring sleep difficulties
Measuring sleep can be difficult as some techniques can be disruptive, invasive, or may require an individual to sleep in a sleep laboratory for a period of time. Changes to an individual’s regular sleep patterns, can influence the quality and quantity of an individual’s sleep. Therefore, sleep measures may not provide a true reflection of an individual’s usual sleeping patterns.
EEG
EEG: An electroencephalograph (EEG) is a device that detects, amplifies, and records the electrical activity of the brain. When neurons communicate, they emit electrical impulses. These impulses are detected by the EEG and then presented as brain wave patterns. Brain waves can be used to make a judgement about the state of consciousness a person might be in, as different brain wave patterns correlate to different states of consciousness. In this way, the different stages of sleep can be correlated with particular brain wave patterns recorded by an EEG.
In order to take these readings, a medical professional or researcher attaches electrodes to the outside of a person’s head.
Brain waves vary in frequency (rate) and amplitude (height). Frequency is the number of brain waves that occur per second, whilst amplitude is the intensity and height of the brain waves. Indicating state of consciousness
EEGs can indicate altered state of consciousness and. asleep. Often, an EEG will show a higher frequency and lower amplitude when in normal waking consciousness, and a lower frequency and higher amplitude during an altered state of consciousness. Therefore, an EEG is likely to show:
• higher frequency and lower amplitude in REM sleep.
• high frequency and low amplitude in NREM sleep stage 1 (transitioning from wakefulness to sleep), but lower frequency and higher amplitude than normal-waking consciousness.
• medium frequency and medium amplitude in NREM sleep stage 2 (light sleep).
• lower frequency and higher amplitude in NREM sleep stage 3 (deep sleep).
A strength of EEGs as a measure of sleep is that it is useful for sleep studies or diagnoses of patients with brain damage or a neurological or mental disorder. However, a limitation of EEGs as a measure of sleep is that it measures neural activity underneath a thick and hard skull and thus is not entirely precise. It also does not pinpoint or identify functional or dysfunctional areas of the brain as well as neuroimaging techniques, such as an fMRI.
EMG
EMG: An electromyograph (EMG) is a device that detects, amplifies, and records the electrical activity of the body’s muscles. By attaching electrodes to the skin above the muscles under investigation, the movement and tension of muscles are recorded.
Muscle movement and tension can be used to identify the different stages and types of sleep an individual may be experiencing through gathering information about how active a person’s muscles are. During REM sleep, EMG readings show low activity, due to there being low levels of physiological activity during this type of sleep. During NREM sleep, EMG readings show medium/moderate activity, due to there being some physiological activity during this type
of sleep. However, as NREM sleep stages progress, an EMG is likely to show lower activity
as movement is less likely to occur (although it is still possible).
EOG
EOG:An electro-oculograph (EOG) is a device that detects, amplifies, and records the electrical activity of the muscles responsible for eye movement. The movement of these muscles, and therefore movement of the eyes, is measured by electrodes that are attached to the skin above the muscles.
Eye movements, which are facilitated by the movements of muscles surrounding the eyes, are a physiological response that can be used to investigate the type of sleep a person is experiencing. One of the main distinguishing features of REM sleep and NREM sleep is eye movement. Therefore, EOGs are helpful in determining what type of sleep an individual is experiencing. During REM sleep, an individual experiences rapid eye movement, so an EOG is likely to show high activity. By comparison, during NREM sleep, an individual does not experience rapid eye movement, so an EOG is likely to show low activity.
Sleep diaries
Sleep diaries: Sleep diaries are a record containing self-reported descriptions from an individual about their sleeping periods, including an estimated time spent sleeping and judgements they might have about the quality and nature of their sleep. It can include both qualitative and quantitative information. This information is recorded over a period of time, most commonly a few weeks. This method is subjective and therefore can be less reliable than objective measures, such as EEGs, as individuals may not be able to determine the exact time they fell asleep or be able to remember the quality of their sleep upon waking.
Some of the information that can be recorded by an individual in a sleep diary include:
• the duration of sleep
• the 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.
Sleep diaries are beneficial as they provide qualitative information and therefore are often extensive in detail and description. However, as the patient is responsible for collecting
and reporting the information within a sleep diary, it is subjective and therefore may not be accurate. Further, as sleep diaries are also interpreted by a doctor or professional, this leaves more room for error and inaccuracy.
Video monitoring
Video monitoring: Video monitoring involves the use of camera and audio technologies to record an individual as they sleep. This 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.
Video monitoring is particularly useful for individuals with sleep disorders, as their behaviours during sleep can be observed. Video monitoring can also be used in conjunction with physiological measures to give validity to a phenomenon. For example, a spike in an EMG recording could correspond to bodily movement in the bed, which would be validated with video monitoring.
The interpretation of video monitoring is subjective. For example, it may be unclear whether an individual seen to be getting out of bed during the night is awake or sleep-walking.
