Unit 1: Ch 3 - Sleep

Partial sleep deprivation

getting less than the required amount of sleep

We enter the REM stage approximately ____ minutes after falling asleep

90

Galvanic Skin Response (GSR)

A physiological response that indicates the change in the resistance of the skin to an electrical current. The experience of high emotional arousal gives a rise in sweating, which is shown in a GSR as an increase in electrical conductivity (that is, a decrease in electrical resistance) Pro => provides useful informational about an individual's state of consciousness, particularly the level of alertness Con => can be misleading as changes in physiological responses occur for many reasons apart from a change in the state of consiousness

Electromyograph (EMG)

Detects, Amplifies and Records Electrical activity occurring in the muscles, Indicates: changes in muscle movement and muscle tension by surface electrodes. Measures: muscle activity and muscle tone throughout the sleep cycle Value: Identifies the systematic changes in muscular activity during a nights sleep

Electroencephalograph (EEG)

Detects, Amplifies and Records Electrical activity of the brain. Measures: the changes in electrical activity shown as distinctive brainwaves on a graph with the frequency and amplitude of each kind of brainwave associated with a different stage of sleep. Value: Enables researchers to distinguish between the 5 stages of sleep

Electro-Eculogram (EOG)

Detects, Amplifies and Records Electrical activity of the muscles that control eye movement. Measures: changes in eye movements during different stages and types of sleep.

Total sleep deprivation

going without sleep for an entire 24-hour period

chronic sleep deprivation

going without sleep over an extended period

Cataplexy

muscle paralysis during REM

sleepwalking is also called

somnambulism

Amplitude

the intensity of the brain waves and is estimated by the size of the brain waves

Frequency

the number of brain waves

Effects of chronic sleep deprivation

Psychological: - Anxiety disorders - Hallucinations - Delusions - paranoia Linked with: - Heart disease - Diabetes - Obesity - Cancer

Sleep lab

- A controlled environment - enables the electronic recording of muscle activity, eye movement, heart rate, body temperature, respiration and other bodily functions by the researcher

Sleep

- A regularly occurring altered state of consciousness - which is characterised by a loss of conscious awareness

Self-report

- A self-reported record of an individual's sleep and waking time and activities throughout the day - usually over a period of several weeks. - It measures various behaviours of interest during the sleep-wake cycle. Pro => Can be used to diagnose causes of sleep phenomena and disorders Con => 1. Missing entries and incompletion. 2. Inaccurate reporting: participants may not be willing to share private thoughts, emotions and dreams. 3. Participants may not be able to remember dreams and other information. 4. The researcher may misinterpret descriptions

Why do we need sleep?

1. Restoration Recovery from physical and mental exertion Repair damaged cells Replenish energy stores Memory formation 2. Survival Night time is dangerous for humans Being inactive during this time aids our survival as we are less likely to be eaten!

Video monitoring

- A sleep measure assessment - where a person's sleep positions are recorded for later analysis. - It measures externally observable physiological responses and changes - in types and patterns of sleep and dreaming Pro => Particularly useful in studying sleep disorders. Useful for identifying activity of sufferers of sleep disorders Con => Observations can be subjective

Hypnogogic/hypnopompic state

- A state that is experienced just between wakefulness and entering stage 1 of non-REM sleep. - It is characterised by slow eye rolling movements and deep relaxation. Duration: 1-2 mintues May experience: - flashes of light or colour - feelings of floating and weightlessness - dreamlike images that resemble vivid photographs - swift, jerky movements and a sense of falling or slipping.

Microsleep

- A very short period of drowsiness or sleeping - that occurs while the person is apparently awake. Occurs after 3 or 4 sleepless days, people automatically drift into periods of microsleeps and individuals may have no recollection of what happened during the microsleep.

Criticisms to restorative theory

- Assumes more sleep is needed to recover when physically active- yet physically disabled people sleep the same amount. - Assumes the body rests during sleep- yet the brain is active during sleep, increased blood flow and energy expenditure occurs during REM sleep.

Criticisms to survival theory

- Assumes sleep is useful but not essential- yet all species must sleep. - Assumes sleep is a way to hide safely from predators- yet loss of awareness can make animals very vulnerable

Sleep-wake cycle shift/ sleep phase onset:

- Hormonally induced shift of the body clock forward

Evidence for restorative theory

- Individuals deprived of sleep for more than 24 hours tend to sleep more the next time they are allowed - The body is actually 'at rest' during sleep. Physiological funtions such as heart rate and breathing rate slow down and muscles are relaxed compared to the awake state. - Organisms with higher metabolic rates sleep more than those with lower rates - Sleep increases immunity to disease and people tend to sleep longer during an illness - Sleep activates growth hormone which promotes body repair (NREM Stage 4) - Sleep helps consolidate memories - More REM sleep occurs in infants which is when the brain is developing than in older people - People who are ill sleep more, indicating that sleep assists recovery - Those who are involved in physically demanding tasks or activities sleep more - Babies have a higher proportion of REM sleep than adults due to the peak of growth in cognitive development

Polysomnography

- Intensive study of a sleeping person - Involving simultaneous monitoring and recording - Of various physiological responses of the sleeper - During the course of the night

Paradoxical sleep

- Internally, the brain and body are active - While externally the body appears calm and inactive

Sleep diary

- Self-reported record - Of an individual's sleep and waking time activities - Usually over a period of several weeks

Sleep debt

- Sleep that is owed and needs to be made up

REM rebound

- The tendency - for REM sleep to increase following REM sleep deprivation (created by repeated awakenings during REM sleep)

Side effects of partial sleep deprivation:

- Tiredness - Lack of energy - Lapses in attention - Inability to concentrate - Low level of motivation - Loss of interest - Impaired motor skills - Irritability - Slower reaction times - Impaired cognitive skills - Impaired memory processes

Polysomnogram

- a continuously moving chart - that displays data collected simultaneuously from EEG, EOG, EMG and other devices

Circadian rhythm/ cycle:

- a cycle during which hormones are produced to control body functions

Evidence for survival theory

- animals sleep less to find more food to survive - small animals sleep more to hide from predators while large animals sleep less to be ready to escape from predators - during sleep, the metabolism slows down, reducing the need for food and thus conserving energy

Features of sleep cycles

- progress through cycles of about 1 1/2 hours - 4-5 cycles - periods of deep sleep occur earlier in the night - during an 8 hour sleep period, we dream every 90 mins - an adult experiences a total of 1-2 hours REM sleep - each session increases as the night goes on - starting from 10mins to 30+ mins in the morning

Survival theories of sleep (also called adaptive theories, evolutionary theories and preservation and protection theories)

- propose that sleep evolved to enhance survival - by protecting an organism through making it inactive during the part of the day - when it is most risky or dangerous to move about

Restorative theories (also called recovery theories or restore and recovery theories)

- propose that sleep provides 'time out' to help us recover from depleting activities during waking time - that use up the body's physical and mental resources

Sleep-wake Cycle Shifts During Adolescence

During adolescence, the release of melatonin occurs 1-2 hours later compared with children and adults, therefore there is a shift of the body clock, forward by about 1-2 hours, making the adolescence sleepier later.

NREM: Stage 4 (Measures, duration, physiological changes and special features)

EEG: Mostly Delta waves. High amplitude+low frequency EOG: No eye movement EMG: Barely any muscle movement (completely relaxed) Duration: 20 minutes at beginning, less as night goes on Physiological changes: Heart rate and breathing most regular and at their slowest, body temp at its lowest Special features: Sleep talking+walking occurs

Features of REM sleep 85% of dreaming

EEG: Sawtooth patterns of Beta-like waves EOG: Rapid eye movement EMG: Lack of tension/tone of muscles;occasional twitch Duration: A few minutes to an hour, lengthening as night progresses Physiological changes: Breathing and heart rate becomes more rapid and irregular, body temperature varies and blood pressure rises Special features: sawtooth waves - special theta-like waves paradoxical (contradictory) sleep because it involves heightened brain activity, faster heart rate and breathing rate, but virtual muscle paralysis (atonia)

NREM: Stage 3 (Measures, duration, physiological changes and special features)

EEG: Theta waves and some Delta waves. Higher amplitude. Lower frequency. EOG: Eyes do not move EMG: Muscles are relaxed Duration: 10 minutes Physiological changes: Breathing becomes more slow and steady, heart rate, blood pressure and body temperature continues to drop Special features: Emergence Delta waves (20-50%)- indicates deep sleep

NREM: Stage 2 (Measures, duration, physiological changes and special features)

EEG: Theta waves. Moderate-high amplitude. Moderate-low frequency. EOG: Limited eye movement, eyes stop rolling EMG: Limited muscle movement, more relaxed Duration: 10- 20 minutes, makes up half of our total sleep Physiological changes: Breathing becomes more regular, heart rate is slower, body temperature drops Special features: K-complex (single, large bursts of high amplitude waves, occur once a minute) and sleep spindles (short bursts of increased brainwave frequency)

NREM: Stage 1 - Light sleep (Measures, duration, physiological changes and special features)

EEG:Alpha+Theta waves. Moderate amplitude+frequency EOG: Some eye movements EMG: Some body movements Duration: 5-10 minutes Physiological changes: Breathing becomes irregular, decrease in heart rate, body temperature and muscles tension Special features: hypnogogic state possible hypnic jerk (involuntary muscle contraction)

Effects of total sleep deprivation

Psychological: Affective: - Mood disturbances - high emotionality, confusion and irritability, feelings of sadness - Previously enjoyed activities seem boring - Lack of motivation - lack of energy Behavioural: - Slowed performance - Clumsiness, injuries - Risk-taking behaviour Cognitive: - Difficulties paying attention and concentrating - Difficulty processing info - Difficulty thinking and reasoning - Memory problems - Impaired creativity - Distorted perceptions Physiological: - Sleepiness - Fatigue - Hand tremors - Drooping eyelids - Difficulty focusing the eyes - Lack of energy and strength - Slurred speech - Increased sensitivity to pain - Heart and respiratory become slower - Body temperature drops - Impaired immune system

EOG readings through the stages of sleep

Records eye movements through small discs or electrodes attached to the skin around the eyes Awake: Few or many eye movements Drowsy: Slow, gentle, rolling eye movements Stage 1 Sleep (NREM): Slow, gentle, rolling eye movements Stage 2 Sleep (NREM): Rare eye movements Stage 3 Sleep (NREM): Rare eye movements Stage 4 Sleep (NREM): Rare eye movements REM Sleep: Bursts of rapid eye movements

EMG readings through the stages of sleep

Records the electrical activity created by active muscles Awake: High to moderated muscle activity, depends on muscle tension Drowsy: Muscles relaxed Stage 1 Sleep (NREM): Moderate to low muscle activity Stage 2 Sleep (NREM): Moderate to low muscle activity Stage 3 Sleep (NREM): Low muscle activity Stage 4 Sleep (NREM): Low muscle activity REM Sleep: Mostly no activity, occasional twitches, no muscle movement (atonia)

Features of NREM sleep

Sleep stages 1 through 4, which are marked by an absence of rapid eye movements, relatively little dreaming, where the body's physiological functions and brain activities slow down throughout the stages. This is when the body recovers, body tissues are repaired, waste materials are removed and neurotransmitters are replenished.

What is the sequence of the sleep cycle like?

Stage 1, 2, 3, 4, 3, 2, REM, 2, 3 etc

Characteristics of sleep

There are 4-5 continuous sleep cycles per night Each sleep cycle (REM & NREM) lasts 80-120 mins Approximately 80% of adult sleep is NREM

Brainwave table

Type, Frequency, Amplitude, When does it occur?

Heart rate (ECG) and Body temp

Value: Dramatic fluctuations can indicate sleep phenomena

When we are awake and alert, our brain emits _____ waves, and when we are drowsy, our brain emits _____ waves.

beta, alpha

Heart rate (ECG) and body temp. Both gradually ______ as we drift from a light sleep into a deeper state of sleep and _______ as we drift from deeper sleep into light sleep.

drop, increase Core body temp. can drop by more than 1°C while asleep