How Does Sleep Affect Mental Processes And Behaviour

Regular and naturally occurring altered state of consciousness that involves a loss of awareness and disengagement with internal and external stimuli

Two distinct states:

• NREM (non-rapid eye movement sleep)

• REM (rapid eye movement sleep)

Occur in a continuous cycle.

The full duration of time spent asleep. A sleep episode is made up of multiple repeated cycles of REM and NREM sleep, called sleep cycles.

Consists of a period of NREM sleep (but not necessarily all four stages) and then a period of REM sleep

• Lasts 80-120 minutes so we go through this approx. 4-5 times a night

A type of sleep characterised by rapid eye movement, high levels of brain activity, and low levels of physical activity. Eyes move rapidly beneath eye lids.

• Irregular beta/beta like brainwaves

• REM periods lengthen and get closer together as the night progresses

• Highly active brain and less active body

• Virtually paralysed, meaning most muscle movement is not possible

• Relatively light stage of sleep

• Vivid dreaming

• Makes up approximately 20-25% of sleep episode for most age groups

• Increases as sleep episode progresses

• Lasts little time near the start of sleep, but can last hours later on

A type of sleep characterised by a lack of rapid eye movement and is subdivided into three different stages

• Less active brain

• Physical movement is possible and body is seen as ‘more active’. Movement decreases over the progress of the stages

• Muscle movement possible

• Dreams can occur but often non-vivd. Dreams not frequently recalled

• Amount of this sleep is highest during first half of sleep cycle

• Approximately 75-80% of sleep and becomes shorter with each sleep cycle

• Subdivided into three stages

Drift in and out of true sleep. Gradually lose awareness of surrounding. Physiological changes indicate lowered arousal and hypnic jerks occur as muscles relax.

• Lasts 5-10 minutes.

Point in which you are truly asleep. Sleep is less easily disturbed than previous stage. Movements lesson, breathing becomes regular, BP and Body temp continue to drop, HR slower.

• Lasts 10-20 minutes

Start of deeper period of sleep (moderately deep sleep). Physiological responses continue to slow. Less responsive to outside world, difficulty to wake and are groggy and disoriented if woken

• Lasts approx. 10 minutes

• Theta and <50% Delta waves occur

Internal body and brain active - shown through physiological measures such as:

• EEG → Irregular beta

• EOG → High

• HR, BT → High

External body relaxed - shown through physiological measures such as:

• EMG → Very low activity

May need REM to consolidate memories by strengthening neural connections

The number of brain waves per second

The height of the peaks and troughs of the curved graph that represents brain wave activity

Detects, amplifies and records electrical activity of the brain. Small electrodes are attached to the surface of the scalp at the top and sides of the head in order to detect electrical activity.

• Alternatively, a swimming cap device could be worn

Detects, amplifies and records electrical activity of the muscles that move the eyes. Electrical activity is produced by the muscles that control eye movements. This device can therefore measure eye movements and eye position. This is done by attaching electrodes to areas of the face surrounding the eyes

• Used to measure changes in eye movements over time during different stages of sleep and while dreaming

Recording generally show strength of electrical activity occurring in the muscles, which indicates changes in muscle activity and muscle tone. Information about electrical activity is obtained by attaching electrodes to the skin above the muscles which are to be monitored

Frequency: High

Amplitude: Low

Frequency: High (but lower than beta)

Amplitude: Low (but higher than beta)

Frequency: Medium

Amplitude: Medium-high

Frequency: Low

Amplitude: High

The use of camera and audio technologies to record an individual as they sleep. Useful for individuals with sleep disorders as their behaviours can be observed as they sleep.

A record containing self-reported descriptions from an individual about their sleeping periods, including an estimated time spent sleeping and judgements they might have about the quality and nature of their sleep

• The duration of sleep

• The quality of sleep

• Thoughts and feelings before going to sleep

• Thoughts and feelings after waking up

• Behaviours before going to sleep

• Behaviours after waking up

• The number of times sleep was disrupted

Changes in bodily functions or activites that repeat through time in the same order. Examples:

• Blood sugar levels

• Digestive secretions

• Body temperature

A biological rhythm that involves changes in bodily functions or activities that occur as part of a cycle with a duration of about 24 hours

• Most extensively studied, and happens due to both internal and external factors

A biological rhythm that involves changes in bodily functions or activities that occur as part of a cycle shorter than 24 hours

• Sleep cycle

Cycles that last longer than a day

• Menstruation

An area of the hypothalamus that is responsible for regulating an individuals sleep-wake patterns. Regulates the timing and activity of the sleep-wake cycle. Receives both external and internal cues. Receives information about the amount of incoming light from the eyes and adjusts our sleep-wake cycle accordingly. Sends messages to the pineal gland to release less or more of the hormone melatonin into the blood.

Involves information from the environment, such as the presence or absence of light

Involve information that originates within the body (such as the expression and suppression of particular genes, known as clock genes)

A hormone released by the pineal gland typically at night-time to induce sleep as part of the sleep-wake cycle

1 → SCN receives external and internal cues

2 → SCN sends neural messages to the pineal gland to produce and release melatonin

3 → The pineal gland releases melatonin into the blood stream which promotes feelings of calm and relaxation, therefore promoting sleep

Many characteristics of sleep that can change over the lifespan, those characteristics being:

• Sleep onset

• Sleep duration

• Awakenings during sleep

• Proportions of REM sleep

• Proportions of NREM sleep

Sleep duration is the highest it will ever be, approx. 16 hours. 50/50% of each sleep episode is REM/NREM sleep.

• Lifespan from 1-15 days old

Sleep decreases est. to 13.5 hours. Proportion of REM and NREM sleep in sleep episode changes to 35% and 65% respectively

• Lifespan period 3-24 months of age

Sleep period decreases again to est. 11 hours. NREM sleep period increases to 80% per sleep episodes. Variations of the amount of REM and NREM as this age period is quite expansive

• Lifespan period of 2-14 years

Sleep duration decreases to est. 9 hours. REM and NREM period remain consistent in each sleep episode est. 20% and 80% (respectively). Experience biological delayed sleep onset, meaning sleepier later and wake up later

• Lifespan period of 14-18 years old

Sleep period duration decrease to 7.75 hours. REM and NREM stay 20& and 80% (respectively)

• Lifespan age period of 18-30 (young adulthood) and 30-75 (middle adulthood)

Duration of sleep decreases to approx. 6 hours. REM and NREm stay 20% and 80% (Respectively). Experience advanced sleep phase syndrome, which is a biological shift forward in sleep-wake cycle, meaning they become sleepier earlier and wake up earlier

• Lifespan period of 75+

Alpha-theta brainwaves

Theta brainwaves

Delta brainwaves

Beta-like brainwave

Beta Brainwaves

Alpha Waves

Delta Waves