6A: Sleep as a psychological construct

What is consciousness?

The awareness of internal mental processes (thoughts, feelings, sensations) and the external world.

Why is consciousness considered a psychological construct?

It cannot be directly measured or observed, only inferred through behaviour, physiology, or self-report.

Is there a specific brain structure responsible for consciousness?

No, there is no single brain structure where consciousness resides.

How is consciousness typically measured?

Through physiological changes, observable behaviours, and self-report methods.

What are the two main states of consciousness?

Normal waking consciousness and altered states of consciousness.

What is normal waking consciousness?

When we are aware of our internal and external environments.

Give an example of normal waking consciousness.

Reading a book or having dinner with family.

What is an altered state of consciousness?

A state that differs significantly from normal waking consciousness in levels of awareness.

Give an example of a naturally occurring altered state.

Sleep or daydreaming.

Give an example of an induced altered state.

Alcohol-induced state or anaesthesia.

What is sleep classified as?

A naturally occurring and reversible altered state of consciousness.

What happens to awareness during sleep?

There is reduced awareness and responsiveness to the external environment.

Name four features that characterise sleep.

Reduced behavioural control, less thought control, distorted time perception, cognitive and perceptual distortions.

Why is sleep considered a psychological construct?

Because it is part of consciousness, which itself is a psychological construct.

What are the two types of sleep?

REM (Rapid Eye Movement) sleep and NREM (Non-Rapid Eye Movement) sleep.

How many sleep cycles occur in a typical 8-hour sleep episode?

About five cycles.

How long does one sleep cycle last?

Approximately 90 minutes.

What happens in REM sleep?

High brain activity, low physical activity, and vivid dreaming occur.

How is the body during REM sleep?

Virtually paralysed.

What percentage of sleep is spent in REM sleep?

About 20–25% of a sleep episode.

What happens in NREM sleep?

It has lower brain activity, allows physical movement, and includes less frequent dream recall.

How many stages are in NREM sleep?

Three stages: NREM 1, NREM 2, and NREM 3.

Describe NREM Stage 1.

Light sleep with hypnagogic sensations and hypnic jerks; easy to wake the sleeper.

Describe NREM Stage 2.

True sleep begins, still light; the stage in which people spend most of their sleep.

Describe NREM Stage 3.

Deep sleep; hard to wake the person, and sleepwalking/talking may occur.

Which stage of NREM is deepest?

NREM Stage 3.

When is most NREM sleep experienced?

In the first half of the sleep episode.

What physical activity occurs during NREM?

Muscle movement and physical activity are possible.

When is dream recall most likely?

During REM sleep.

What is a sleep episode?

The full duration of time spent asleep, made up of repeated sleep cycles.

What is a sleep cycle?

A 90-minute period containing both REM and NREM stages that repeats throughout a sleep episode.

What is a hypnogram?

A graph showing stages of sleep, awakenings, and the time spent in each stage during a sleep episode.