7B Techniques used to measure sleep Flashcards
Measuring sleep
detect and record features like the onset of sleep, body movement and wake-up time
enables us to diagnose sleep disorders, tracking how a person’s sleep is affected by various factors such as new medication, or even improving the performance of athletes
Techniques for Measuring sleep
- electroencephalography
- electromyography
- electro-oculography
- sleep diaries
- video monitoring
Combined to a sleep study called polysomnography
Polysomnography
a multi-parameter sleep study used as a diagnostic tool in sleep medicine
Electroencephalography
technique that detects, amplifies and records the electrical activity of the brain
1) electrodes are attached to a person’s scalp or through a cap or headset
2) electrodes detect the synchronised electrical impulses of neurons communicating together beneath the scalp at surface of cortex
3) Wires connected to the electrodes transmit data to an instrument (electroencephalograph) that amplifies the signals to a readable level and then sends them to a computer
4) they are recorded as brain wave patterns and interpreted by a specialist
electrical impulse of one neuron = not strong enough for EEG to detect, so recordings are summaries of the activity of thousands of neurons in the area
identifies stages or abnormal brain activity from the different brain waves
Different brain waves
beta, alpha, theta and delta, they differ in terms of their frequency and amplitude
relate to a persons level of awareness or state of consciousness, and general pattern shows that as frequency decreases the amplitude increases
brain waves decrease as person drifts into deeper sleep stages of sleep cycle
Increase in brain activity during REM sleep is shown by faster brain wave patterns
Frequency of brain waves
indicates the speed of brain waves or how much activity is occuring every second
can be visually identified in a brain wave recording accoring to how close together the waves are and the number of times the wave repeats in a 1-second interval
slower-frequency brain waves are prevalent when we are tired, relaxed or asleep
faster-frequency brain waves are prevalent when we are awake and alert
Amplitude of brain waves
indicates the intensity or strength of the brain wave, or how many neurons are firing at the same time together
can be visually identified in a brain wave recording as the height of the brain waves or the distance between the peaks and troughs
Higher peaks and lower troughs indicate more synchronised brain activity from multiple neurons working on a similar task, such as sleep
lower peaks and troughs indicate groups of neurons are working on different tasks, such as driving a car
Beta (frequency and amplitude and state)
Frequency: highest
Amplitude: lowest
State:
- normal waking consciousness
- awake, alert and focused
- high environmental stimulation
- brain working on several things at once
Alpha (frequency and amplitude and state)
Frequency: high
Amplitude: low
State:
- lower alertness
- awake but relaxed
- quiet and calm
- drowsy
- eyes closed
- low environmental stimulation
Theta (frequency and amplitude and state)
Frequency: low
Amplitude: high
States:
- low alertness
- light sleep
- senses withdrawn from the external environment
- deep meditation
Delta (frequency and amplitude and state)
Frequency: lowest
Amplitude: highest
States:
- lowest alertness
- deep N3 sleep
- dreamless sleep
Electromyography
technique that detects, amplifies and records the electrical activity of the skeletal muscles
1) electrodes are attached to the surface of the skin (around jaw, sometimes the legs or other body parts)
2) output is recorded similar to EEG but different names
used during a sleep study to measure muscle tension indicating the stages and type of sleep
deeper sleep decreases muscle movement
detects abnormal movements e.g tossing and turning, grinding teeth or leg movements, which could indicate sleep disorder (periodic movement disorder or sleep bruxism)
**Electro-oculography
**
technique that detects, amplifies and records the electrical activity of the muscles controlling the eyes
1) electrodes are attached to the surface of the skin around the sides of each eye
2) output recorded wave patterns similar to EEG
determine the onset of sleep as well as when the stages and types of sleep occur
deeper sleep = eye movement decreases and slows down. REM sleep eye movement increases
Sleep diaries
subjective, self-report tool used by a person to track their own sleep and wake patterns
aim to identify any patterns or habits that may be leading to the sleep trouble
can provide the sleep specialist with a personal and subjective account of the quantity and quality of sleep being experienced
Recorded for a couple of weeks
Disturbed sleep may be the cause or consequence of a mental health disorder, so once subjective data has been collected through a sleep diary, a sleep specialist can interpret it and make further assessments
A more accurate assessment can be made if information from the sleep diary is combined with information from objective measures such as physiological changes determined by an EEG, EOG or EMG
What sleep diaries include
spaces to record the time of sleep onset, waking time, how the person felt upon waking and any disturbances to sleep such as periods of waking, or unusual behaviours such as sleep walking or night terrors
may include space to track anything else that could be affecting a person’s sleep patterns, such as caffeine intake over the day, any naps taken and exercise completed
