Psych U4 A1

Consciousness

Is awareness of your own internal mental processes, including your thoughts, feelings, sensations and perceptions as well as your awareness of the external world around you.

psychological construct

Because it cannot be objectively observed or measured by collecting data, but it is widely understood to exist.

Normal waking consciousness (NWC)

is a state associated with being aware of our internal and external environments.

Altered state of consciousness (ASC)

is any state that differs in awareness from NWC. Levels of awareness can be lower or higher than in NWC.

Naturally occurring altered states of consciousness

Occur without any external influence, such as sleep or a state of fatigue.

Induced altered states of consciousness

Are brought about on purpose, such as an alcohol-induced state, an anaesthetised state for a surgery or a meditative state.

Sleep

Is a naturally occurring and reversible altered state of consciousness, characterised by a reduction in awareness and responsiveness to external surroundings.

REM

• is a type of sleep characterized by a quick darting of the eyes behind closed eyelids and an increase in physiological activity.

  •The sleeper is considered to have a highly active brain and a less active body during REM sleep.

  •The sleeper is virtually paralysed during REM sleep, meaning that most muscle movement is not possible.

  •Sleepers can be woken fairly easily.

  •Vivid dreaming tends to occur during REM sleep. The sleeper frequently recalls dreams when woken during REM sleep.

  •REM sleep makes up approximately 20–25% of a sleep episode for most age groups.

  •The amount of time spent in REM sleep increases as the sleep episode progresses, with the largest amount of REM in the sleep cycle occurring immediately before waking.

NREM

• is a type of sleep characterized by a progressive decline in physiological activity.

  •Muscle movement is possible for the sleeper during NREM sleep.

  •Dreams can occur in NREM sleep but they are often non-vivid (as opposed to REM sleep) and difficult to recall.

  •The amount of time spent in NREM sleep is highest during the first half of a sleep episode.

  •NREM sleep makes up approximately 75–80% of a sleep episode.

  •NREM sleep tends to become shorter with each sleep cycle.

NREM 1

•A transitional phase between wakefulness and sleep.

•Considered to be light sleep, where physiological responses begin to slow down, including brain activity, heart rate and body temperature.

•When a person ‘dozes’ off to sleep and when they are most easily woken up.

•This transition is signified by the experience of the hypnagogic state, in which some people experience feelings of floating or falling, or a sudden jerk (referred to as a hypnic jerk).

•In this stage, the sleeper loses awareness of themselves and their surroundings but is still aware of faint sounds in the environment.

NREM 2

•Also considered light sleep, during which physiological responses continue to slow down.

•A person can still wake relatively easily.

•Individuals spend the majority of their time asleep in NREM stage 2.

•The sleeper is considered ‘truly’ asleep, due to the types of brain waves occurring.

NREM 3

•Considered to be deep sleep, during which physiological responses are at their slowest.

•A person is most difficult to wake.

•Known as ‘slow wave sleep’ as brain activity is at its slowest.

•Experienced more in the first half of the night and lessens as the sleep episode progresses.

•If the sleeper is woken during this stage they are likely to feel drowsy and disoriented.

•During this stage, sleepwalking and sleep talking are most likely to occur.

Electroencephalography (EEG)

Is a technique that detects, amplifies and records the electrical activity of the brain.

•As different types and stages of sleep produce different brain waves, and EEGs may be used to identify a particular stage or abnormal brain activity that differs from what would usually be expected.

frequency

Of a brain wave indicates the speed of the brain waves or how much activity is occurring every second.

oSlower frequency brain waves are prevalent when we are tired, relaxed or asleep.

oFaster frequency brain waves are prevalent when we are awake and alert.

amplitude

Of a brain wave indicates the intensity or strength of the brain wave, or how many neurons are firing at the same time together.
Lower peaks and troughs indicate groups of neurons are working on different tasks, such as driving a car.

Higher peaks and lower troughs indicate more synchronised brain activity from multiple neurons working on a similar task, such as sleep.

Electromyography (EMG)

Is a technique that detects, amplifies and records the electrical activity of the skeletal muscles.

•An EMG may be used during a sleep study to measure muscle tension, which can indicate the stages and type of sleep the person is experiencing.

§In general, more muscle tension indicates greater alertness.

Electro-oculography (EOG)

Is a technique that detects, amplifies and records the electrical activity of the muscles controlling the eyes.

As you drift into deeper sleep, your eye movement decreases and slows down, and when you experience REM sleep, your eye movement increases.

Sleep diaries

Are a subjective, self-report tool used by a person to track their own sleep and wake patterns.

They aim to identify any patterns or habits that cause sleep trouble, and they provide the sleep specialist with a personal and subjective account of the quantity and quality of sleep being experienced

Video monitoring

•During a sleep study, video monitoring is used to collect qualitative visual and audio information about a person’s sleep.

•Video monitoring is used alongside EEGs, EOGs and EMGs.

Circadian rhythms

are biological processes in all animals that coordinate the timing of activity of body systems over a 24-hour period.
e.g. circadian rhythm

Ultradian rhythms

are biological processes that coordinate the timing of activity of body systems over periods of less than 24 hours.

sleep episode

consists of several sleep cycles occurring as ultradian rhythms

Suprachiasmatic nucleus

Is a part of the brain’s hypothalamus, which functions as the master body clock.

Zeitgebers

External cues, such as light, exercise, social activity, eating patterns and temperature.

SCN and Melatonin at night

•At night-time, when the eyes detect no light, the suprachiasmatic nucleus sends a signal to the pineal gland in the human brain.

•This results in the pineal gland releasing melatonin, a hormone that induces drowsiness. The increased release of melatonin by the pineal gland at night-time induces sleepiness and decreases cell activity.

SCN and melatonin in the day

•During the day, when the eyes detect more light, the suprachiasmatic nucleus sends inhibitory messages to the pineal gland, resulting in the inhibition of melatonin release by the pineal gland.

•Less melatonin release by the pineal gland increases cell activity in the body.

•The result is that a person does not feel drowsy, and therefore wakefulness is promoted during the day.

Cortisol

Is a hormone that is responsible for increasing alertness and maintaining heightened arousal.

•released by the adrenal glands

•released in the morning

•promotes wakefulness and alertness.