Conditions that alter the EEG pattern :::
1.Age: Alpha and theta waves are the characteristics of infancy and childhood with the advent of adolescence a gradual a- pattern appears
2.Blood -glucose level:: Hypoglycemia decreases the frequency of rhythm and even causes appearance of rhythm Hyperglycemia produces little effect on cortical potential
3.Hypoxia : Depending on the severity of hypoxia EEG the rhythm is slowed down and there is the appearance of $waves
4.Sleep and EEG:: when a person is alert he shows low voltage waves (B-waves) During drowsiness or light sleep slower but larger waves are seen In deep sleep there are often irregular delta waves having frequency less than 4 per second This pattern during deep sleep is sometimes replaced by low voltage high frequency irregular waves alongwith eye movements This is termed as rapid eye movement (REM) Sleep This phase is important and absence of REM sleep may lead to psychological disturbances
FIG EEG IN SLEEP
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