States of Consciousness
Consciousness is our awareness of internal states and external stimuli. It exists on a continuum, from focused attention to unconsciousness. Explore the two primary states below.
Normal Waking Consciousness (NWC)
The state of being awake and aware of thoughts, feelings, and what is happening around you.
- Clear awareness of internal/external world
- Good sense of time and place
- Voluntary control over attention and actions
- Can perform controlled and automatic processes
Altered State of Consciousness (ASC)
Any state that is characteristically different from NWC in terms of awareness and experience.
- Perceptual & cognitive distortions (e.g., time)
- Changes in emotional awareness
- Reduced self-control
- Can be natural (sleep) or induced (meditation)
Measuring States of Consciousness
Psychologists use physiological measures to objectively distinguish states of consciousness. Click the buttons to learn about the three main tools used in polysomnography.
EEG (Electroencephalograph)
Detects, amplifies, and records the electrical activity of the brain. It shows brainwave patterns (frequency/amplitude) that differ between alertness and sleep stages.
EMG (Electromyograph)
Detects, amplifies, and records the electrical activity of muscles. It indicates muscle tone, which is high when awake but very low in REM sleep.
EOG (Electrooculograph)
Detects, amplifies, and records the electrical activity of muscles controlling eye movements. It is key for identifying REM sleep.
Effects of Partial Sleep Deprivation
Getting insufficient sleep impairs functioning across three key domains: Affective, Behavioural, and Cognitive (ABC). Performance after 17 hours awake can be equivalent to a BAC of 0.05.
Affective (Mood)
Difficulty controlling emotions. Leads to irritability, mood swings, heightened anxiety, and reduced motivation.
Behavioural (Actions)
Slowed reaction times and clumsiness. Can lead to fatigue, microsleeps, and reduced motor control.
Cognitive (Thinking)
Impaired attention, concentration, and memory. Decision-making and problem-solving abilities decline.
The Sleep Cycle: Ultradian Rhythms
Within a night, we cycle through different stages of sleep in predictable 90-minute ultradian rhythms. A cycle involves progressing through NREM stages before entering REM. Click ‘Start Cycle’ to see how it works.
Ready to Sleep?
Click the start button to begin the sleep cycle.
Sleep Across the Lifespan
The duration and composition of sleep change significantly as we age. Generally, we need less sleep overall, and the proportion of REM and deep sleep decreases. Click the cards to learn more.
Newborn
15-16 hours/day
Child
10-11 hours/day
Adolescent
8-9 hours needed
Adult & Older Adult
6-8 hours/day
Select an age group to learn more.
Sleep Disturbances and Disorders
Sleep disorders disrupt the normal sleep-wake cycle. They are broadly categorized as Dyssomnias (problems with sleep timing/quantity) and Parasomnias (abnormal events during sleep).
Dyssomnia: Sleep-Onset Insomnia
A disorder involving persistent difficulty falling asleep.
- Core issue is initiating sleep.
- Leads to a change in the quantity and timing of sleep.
- Person cannot get to sleep, resulting in sleep loss.
- Can disrupt the circadian rhythm, causing a delayed sleep phase.
Parasomnia: Sleep Walking
A disorder involving getting up and walking around while in deep NREM sleep.
- Core issue is an abnormal event during sleep.
- Does not typically alter total sleep time or circadian rhythm.
- The person is asleep, but performing unusual behaviours.
- Disrupts the quality of sleep by fragmenting deep sleep.
Interventions for Sleep Disorders
Effective, non-pharmacological treatments address the underlying causes of sleep disorders. Explore two key interventions below.
Theories of Sleep
Why do we sleep? Psychologists propose two major theories that are complementary, not mutually exclusive. Explore them below.
