<prompt> In a healthy alert adult sitting with eyes closed, which of the following EEG rhythms will be seen when electrode is placed in occipital region?Delta 0.5-4 HzTheta 4-7 HzAlpha 8-13 HzFast irregular low-voltage activity  <response>: Ans. c. Alpha waves Ref. Guyton physiology 11th ed., 742NORMAL SLEEPStage of sleepCharacteristic features1. Stage 1 5EEG: The appearance of theta waves slow 3 to 7 cycles per secondDisappearance of alpha waves - drowsy rapid 8 to 12 cycles per second2. Stage 2 45Longest stageEEG: K complexes sleep spindles very rapid 12 to 14 cycles per second3. Stage 3 12.5EEG: appearance of delta waves slowest 2 cycles per second.Hardest to arouseTends to vanish in the elderlyStage 3 with stage 4 are called slow wave sleep or delta sleep4. Stage 4 12.5EEG: continuation of delta wave5. REM sleep 25EEG: Saw-tooth wavesREM like SEX: Pulse PenileClitoral arousal, but with ageLengthens in time as the night progressesIncreased during the second half of the nightFour simple periodic rhythms recorded in the EEG are alpha, beta, delta, and theta. The four basic rhythms have been associated with various states.RhythmFreq HzAmp mValpha8-1320-200beta13-305-10delta1-520-200theta4-810Alpha: In general, the alpha rhythm is the prominent EEG wave pattern of an adult who is awake but relaxed with eyes closed. Each region of the brain had a characteristic alpha rhythm but alpha waves of the greatest amplitude are recorded from the occipital and parietal regions of the cerebral cortex. In general, amplitudes of alpha waves diminish when subjects open their eyes and are attentive to external stimuli although some subjects trained in relaxation techniques can maintain high alpha amplitudes even with their eyes open.Beta: Beta rhythms occur in individuals who are alert and attentive to external stimuli or exert specific mental effort, or paradoxically, beta rhythms also occur during deep sleep, REM sleep when the eyes switch back and forth. This does not mean that there is less electrical activity, rather that the positive and negative activities are starting to counterbalance so that the sum of the electrical activity is less. Thus, instead of getting the wave-like synchronized pattern of alpha waves, desynchronization or alpha block occurs. So, the beta wave represents arousal of the cortex to a higher state of alertness or tension. It may also be associated with remembering or retrieving memories.Delta and Theta: Delta and theta rhythms are low-frequency EEG patterns that increase during sleep in the normal adult. As people move from lighter to deeper stages of sleep prior to REM sleep, the occurrence of alpha waves diminish and is gradually replaced by the lower frequency theta and then delta frequency rhythms.Additional Educational Points:NEUROTRANSMITTERS OF SLEEP T SA-ND4Serotonin during sleep -Initiates sleepAcetylcholine during sleep - REM sleepNorepinephrine during sleep -REM sleepDopamine during sleep - arousal wakefulnessCHEMICAL EFFECTS ON SLEEP Tryptophan Serotonin; total sleep time Dopamine agonists Bromocriptine Produces arousal; total sleep time Dopamine antagonists Haloperidol Arousal; Produce sleep Imipramine Stage 4 used for Rx of Enuresis Benzodiazepines Stage 4 used for Rx of Night Terrors Sleepwalking Benzodiazepines withdrawal after chronic use T sleep latency Cant Sleep Alcohol Barbiturate intoxication REM Alcohol Barbiturate withdrawal REMParasomniasParasomniasSleeping StageCharacteristicsRxNightmareBad DreamOccurs during REM sleepMemory of events depends upon awakening. during stress.Reported by 50 of the population.REM suppressants such as TricyclicAnti-depressants TCAsNight TerrorOccurs during stages 3 4Awakened by scream or intense anxietyNo memory of the event. in children BoysNo treatment is necessary OR use drugs to suppress stages 3 A, such as BenzodiazepinesSleeptalkingCan occur in all stages of sleepUsually involves a few words.May accompany night terrors sleepwalking. in children.No treatment is necessary.SleepwalkingOccurs during stages 3 4Sequence of behaviors without full consciousness. No memory of the events. Begins at young age in boysUse drugs to suppress stages 3 4, such as Benzodiazepines. 