Sleep and Dreaming Methodology PAGE 48

EEG  electroencephalogram

EEG

  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 minutes and rarely causes any side effects.   EEGs can also be used to diagnose and manage sleep disorders such as insomnia.insomnia

EMG  Electromyogram

EMG

  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.restless legs syndromeREMnon-REM   The electrodes are generally placed on the chin and along the shin in sleep studies.

EOG  Electrooculogram

EOG

  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 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 Dreaming Sleep Stages and Cycles Page 51

Stages of Sleep  Wakefulness Beta wavesBeta waves Low aplitude, high frequency waves of electrical activity in the brain Low aplitude, high frequency waves of electrical activity in the brain

Stages of Sleep  Relaxation Alpha WavesAlpha Waves High amplitude, slow frequency waves High amplitude, slow frequency waves

Stages of Sleep  Hypnagogic state Muscles active,Muscles active, Slow eye movements Slow eye movements

Stage 1 of Sleep  Theta waves – Slow frequency, irregular amplitude Slow frequency, irregular amplitude

Stage 2  Sleep Spindles Medium amplitude, slow frequency with bursts of high frequency. Medium amplitude, slow frequency with bursts of high frequency. K-Complexes – brain is responsive to external stimuli K-Complexes – brain is responsive to external stimuli Eye and muscle movements are limited, Eye and muscle movements are limited, Easily woken Easily woken

Sleep spindles/k-complex

Stage 3  Delta Waves Increased amplitude, slower frequency (20- 50%) Increased amplitude, slower frequency (20- 50%) NREM NREM Brain unresponsive to external stimuli Brain unresponsive to external stimuli Difficulty in waking Difficulty in waking

Delta Waves

Stage 4  Increase of delta waves to more than 50%  Lowest readings of heart rate, blood pressure and temperature  NREM,  Brain unresponsive to stimuli  Difficulty in Waking

REM  Rapid Eye Movements observed  Wildly oscillating brain waves  Muscles in virtual paralysis  Fluctuations in heart rate, blood pressure and respiration  Difficulty in waking

REM sleep

Sleep Cycles First Cycle  Hypnagogic state  Stage 1  Stage 2  Stage 3  Stage 4  Stage 3  Stage 2  REM  1 min  20 mins  5 mins  40 mins  5 mins  10 mins

Second Cycle  Stage 2  Stage 3  Stage 4  Stage 3  Stage 2  REM  25 mins  5 mins  30 mins  5 mins  10 mins

Third Cycle  Stage 2  REM  30 mins  40 mins

4 th Cycle  Stage 2  REM  70 mins  60 mins

5 th Cycle emergent cycle  Stage 2  REM  Hypnopompic state  May wake

What have you learned?  Page 56, Have a go at the exam answer (8 marks, not 9!) This is all AO1 “Outline the nature of sleep”