Sleep and DreamingSleep and Dreaming

MethodologyMethodology

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EEGEEGelectroencephalogramelectroencephalogram

EEGEEG

An electroencephalogram (EEG) is a recording of brain activity.

The brain's cells produce tiny electrical signals when they send messages to each other. During an EEG test, small electrodes are placed on to your scalp.

They pick up your brain's electrical signals and send them to a machine called an electroencephalograph, which records the signals as wavy lines on to a computer screen or paper.

An EEG is painless, takes 30-45 minutes and rarely causes any side effects.

EEGs can also be used to diagnose and manage sleep disorders such as insomnia.

EMGEMGElectromyogramElectromyogram

EMGEMG

Definition: A measurement of the electrical activity of skeletal muscles are recorded with the placement of small metal discs, called "electrodes," applied to the skin’s surface.

It is useful for assessing nerve and muscle function, diagnosing restless legs syndrome and determining REM versus non-REM sleep.

The electrodes are generally placed on the chin and along the shin in sleep studies.

EOGEOGElectrooculogramElectrooculogram

EOGEOG

An automated method for detecting and counting eye movements.

Using the electrooculogram (EOG) wave form during rapid-eye-movement (REM) sleep is presented.

To measure eye movement, pairs of electrodes are typically placed either above and below the eye or to the left and right of the eye.

If the eye moves from centre position toward one of the two electrodes, this electrode "sees" the positive side of the retina and the opposite electrode "sees" the negative side of the retina. 

What limitations might these What limitations might these measures have?measures have?

EEG cannot determine what areas of the brain are active.

EEG determines neural activity that occurs below the upper layers of the brain (the cortex) poorly.

Often takes a long time to connect a subject to equipment, as it requires precise placement of dozens of electrodes around the head and the use of various gels, saline solutions, and/or pastes to keep them in place.

These measures tell us what is moving, but not why it is moving, we

can only infer reasons..

Biorhythms, Sleep and Biorhythms, Sleep and DreamingDreaming

Sleep Stages and CyclesSleep Stages and Cycles

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Stages of SleepStages of Sleep

Wakefulness Wakefulness • Beta wavesBeta waves

Low aplitude, high frequency waves of electrical activity Low aplitude, high frequency waves of electrical activity in the brainin the brain

Stages of SleepStages of Sleep

RelaxationRelaxation• Alpha WavesAlpha Waves

High amplitude, slow frequency wavesHigh amplitude, slow frequency waves

Stages of SleepStages of Sleep

Hypnagogic stateHypnagogic state• Muscles active, Muscles active,

Slow eye movementsSlow eye movements

Stage 1 of SleepStage 1 of Sleep

Theta waves –Theta waves – Slow frequency, irregular amplitudeSlow frequency, irregular amplitude

Stage 2Stage 2

Sleep SpindlesSleep Spindles Medium amplitude, slow frequency with bursts Medium amplitude, slow frequency with bursts

of high frequency.of high frequency. K-Complexes – brain is responsive to external K-Complexes – brain is responsive to external

stimulistimuli Eye and muscle movements are limited, Eye and muscle movements are limited, Easily wokenEasily woken

Sleep spindles/k-complexSleep spindles/k-complex

Stage 3Stage 3

Delta WavesDelta Waves Increased amplitude, slower frequency (20-Increased amplitude, slower frequency (20-

50%)50%) NREMNREM Brain unresponsive to external stimuliBrain unresponsive to external stimuli Difficulty in wakingDifficulty in waking

Delta WavesDelta Waves

Stage 4Stage 4

Increase of delta waves to more than 50%Increase of delta waves to more than 50% Lowest readings of heart rate, blood Lowest readings of heart rate, blood

pressure and temperaturepressure and temperature NREM, NREM, Brain unresponsive to stimuliBrain unresponsive to stimuli Difficulty in WakingDifficulty in Waking

REMREM

Rapid Eye Movements observedRapid Eye Movements observed Wildly oscillating brain wavesWildly oscillating brain waves Muscles in virtual paralysisMuscles in virtual paralysis Fluctuations in heart rate, blood pressure Fluctuations in heart rate, blood pressure

and respirationand respiration Difficulty in wakingDifficulty in waking

REM sleepREM sleep

Sleep CyclesSleep CyclesFirst CycleFirst Cycle

Hypnagogic stateHypnagogic state Stage 1Stage 1 Stage 2Stage 2 Stage 3Stage 3 Stage 4Stage 4 Stage 3Stage 3 Stage 2Stage 2 REMREM

1 min1 min 20 mins20 mins 5 mins5 mins 40 mins40 mins 5 mins5 mins 10 mins10 mins 10 mins10 mins

Second CycleSecond Cycle

Stage 2Stage 2 Stage 3Stage 3 Stage 4Stage 4 Stage 3Stage 3 Stage 2Stage 2 REMREM

25 mins25 mins 5 mins5 mins 30 mins30 mins 5 mins5 mins 10 mins10 mins 10 mins10 mins

Third CycleThird Cycle

Stage 2Stage 2 REMREM

30 mins30 mins 40 mins40 mins

44thth Cycle Cycle

Stage 2Stage 2 REMREM

70 mins70 mins 60 mins60 mins

55thth Cycle Cycleemergent cycleemergent cycle

Stage 2Stage 2 REMREM Hypnopompic stateHypnopompic state

May wakeMay wake May wakeMay wake

What have you learned?What have you learned?

Page 56,Page 56,

Have a go at the exam answer (8 marks, not Have a go at the exam answer (8 marks, not 9!)9!)

This is all AO1This is all AO1

““Outline the nature of sleep”Outline the nature of sleep”