<prompt> Sleep spindle and K complexes are seen in: RepeatREMNREM Stage IINREM Stage IIINREM Stage IV  <response>: Ans: B NREM Stage II Ref: Pal GK, Reticular Formation, EEG and Sleep, In: Textbook of Medical Physiology, 2nd ed, Ahuja Publishing House, 2011: 119: 895-96Explanation:SleepIt is defined behaviorally by four criteriaReduced motor activityDecreased response to stimulationStereotypic postures in humans, for example, lying down with eyes closedRelatively easy reversibility distinguishing it from coma, hibernation and estivationEEG pattern repeats in every 90 minutesNon-REM phase4 stagesREM phaseLate part of night25 of total sleep periodNon-REM Sleep Slow Wave SleepStage 1Beta to alpha rhythmStage 2Amplitude increasesSleep spindle 12-14 Hz: 50 mV; for about 2 seconds and K complexes high amplitudeStage 3High amplitude: low frequencyStage 4Delta rhythmAutonomic and visceral changes heart rate and BP body temperatureSlow regular respiration GI activity muscle toneNo rapid eye movementAdrenal Steroid Hormones in AdultsSteroidsAverage plasma concentrationfree and bound. mg100 mlAverage amountsecreted mg24 hrGlucocorticoidactivityMineralocorticoidactivityAdrenal Steroids Cortisol12151.01.0Corticosterone0.430.315.0Aldosterone0.0060.150.33000Deoxycorticosterone0.0060.20.2100Dehydroepiandrosterone17520--Paradoxical sleep REM Sleep FeaturesRapid eye movementsEECdeg High frequency; low voltage rhythmdeg PGO spikes Ponto-Geniculo- OccipitalDifficult to arouse; likely to wakeup spontaneouslyDream is remembered sympathetic system HR. BP. RespirationPenile erectionDecreased muscle tone except extraoccular and middle ear 