Psych U4 AOS 1

Sleep

A naturally recurring altered state of consciousness characterised by reduced awareness of the external environment and changes in physiological activity.

Altered state of consciousness

A state in which a person's awareness, perception, cognition and responsiveness differ from normal waking consciousness.

REM sleep

Rapid eye movement sleep; a sleep stage characterised by rapid eye movements, relatively low skeletal muscle activity and brain activity similar to wakefulness.

NREM sleep

Non-rapid eye movement sleep; sleep consisting of stages 1, 2 and 3, generally characterised by progressively deeper sleep.

NREM Stage 1

The lightest stage of NREM sleep, characterised by relaxed muscles, slow eye movements and a transition from wakefulness to sleep.

NREM Stage 2

A stage of NREM sleep characterised by sleep spindles and K-complexes, with reduced responsiveness to the environment.

NREM Stage 3

The deepest stage of NREM sleep, characterised by slow, high-amplitude delta waves and the greatest difficulty waking.

Sleep cycle

A recurring sequence of NREM and REM sleep that occurs approximately every 90 minutes throughout the night.

Ultradian rhythm

A biological rhythm that occurs more than once within a 24-hour period, such as the approximately 90-minute sleep cycle.

EEG (electroencephalography)

A physiological measure that records electrical activity of the brain using electrodes placed on the scalp; it can identify changes in brain-wave activity across sleep stages.

EOG (electro-oculography)

A physiological measure that records eye movements using electrodes placed around the eyes; it is particularly useful for identifying REM sleep.

EMG (electromyography)

A physiological measure that records electrical activity associated with skeletal muscle activity; it can identify the reduced muscle activity characteristic of REM sleep.

Sleep diary

A subjective record in which an individual records information about their sleep, such as bedtime, wake time, sleep duration and perceived sleep quality.

Video monitoring

A method of observing and recording physical behaviours and movements during sleep.

Physiological measure

A measure of a physical or biological response associated with sleep, such as brain activity, eye movements or muscle activity.

Subjective measure

A measure based on an individual's personal perception or experience, such as perceived sleep quality recorded in a sleep diary.

Qualitative data

Non-numerical descriptive information that provides information about the characteristics or subjective experience of sleep.

Quantitative data

Numerical information about sleep that can be measured, counted or statistically analysed.

Sleep-wake cycle

The recurring pattern of periods of sleep and wakefulness across approximately 24 hours.

Circadian rhythm

A biological rhythm that follows an approximately 24-hour cycle.

Suprachiasmatic nucleus (SCN)

A cluster of neurons in the hypothalamus that acts as the body's master biological clock and regulates circadian rhythms.

Melatonin

A hormone produced by the pineal gland that promotes sleepiness and helps regulate the sleep-wake cycle.

Pineal gland

A small endocrine gland that produces and releases melatonin in response to signals from the SCN.

Light-dark cycle

The predictable daily pattern of light and darkness in the external environment that helps synchronise circadian rhythms.

Zeitgeber

An environmental time cue that helps synchronise the body's biological clock with the external environment.

Sleep onset

The point at which an individual transitions from wakefulness into sleep.

Sleep need

The amount of sleep an individual requires to function effectively and maintain health and wellbeing.

Total sleep duration

The total amount of time an individual spends asleep during a sleep episode or period.

Adolescent phase delay

The tendency during adolescence for sleep onset and wake time to occur later, partly due to a delay in the timing of melatonin release.

Delayed melatonin release

The later timing of melatonin secretion during adolescence, contributing to later sleepiness and sleep onset.

Sleep deprivation

A state resulting from obtaining insufficient sleep in terms of quantity and/or quality to meet an individual's sleep need.

Partial sleep deprivation

A state resulting from obtaining less sleep than required, either through insufficient quantity or quality of sleep, without complete loss of sleep.

Full sleep deprivation

A state in which an individual obtains no sleep for a prolonged period, such as remaining awake for an entire night.

Sleep debt

The accumulated difference between the amount of sleep an individual needs and the amount of sleep they actually obtain over time.

Sleep quality

The degree to which sleep is uninterrupted, restorative and sufficient to support effective functioning.

Sleep quantity

The amount or duration of sleep obtained.

Cognitive effects of sleep deprivation

Effects of insufficient sleep on mental processes such as attention, concentration, memory, learning, decision-making and reaction time.

Affective effects of sleep deprivation

Effects of insufficient sleep on emotions and mood, such as increased irritability, negative mood and difficulty regulating emotions.

Behavioural effects of sleep deprivation

Effects of insufficient sleep on observable actions and performance, such as reduced performance, impaired behavioural control and increased risk-taking.

Delayed Sleep Phase Syndrome (DSPS)

A circadian rhythm sleep disorder involving a persistent delay in sleep onset and waking, making it difficult to sleep and wake at socially required times.

Advanced Sleep Phase Disorder (ASPD)

A circadian rhythm sleep disorder involving an unusually early sleep onset and early waking, making it difficult to remain awake in the evening.

Shift work

A work schedule involving employment during hours that differ from the conventional daytime schedule, potentially disrupting the sleep-wake cycle and circadian rhythms.

Circadian rhythm sleep disorder

A disorder involving a persistent misalignment between an individual's biological clock and the external environment, causing difficulty sleeping or waking at socially required times.

Bright light therapy

A treatment involving controlled exposure to bright light at an appropriate time to help adjust the circadian rhythm.

Sleep hygiene

Behaviours and environmental practices that promote healthy and effective sleep.

Daylight

A natural source of light that acts as a zeitgeber and helps synchronise the circadian rhythm with the external environment.

Blue light

A wavelength of light that can suppress or delay melatonin release and therefore potentially delay sleep onset when exposure occurs at night.

Temperature

An environmental factor that can influence sleep and can act as a cue affecting sleep timing and comfort.

Eating patterns

The timing and nature of food consumption, which can influence sleep quality and sleep timing.

Drinking patterns

The timing and type of fluids or drinks consumed, which can influence sleep, particularly when caffeine or large amounts of fluid are consumed close to bedtime.

Sleep-wake schedule

The regular timing of when an individual goes to sleep and wakes, which can influence the consistency and alignment of their circadian rhythm.