Circadian Rhythms and Sleep 1 Endogenous Cycles a Circannual Rhythms Internal cycles controlling cycles in physiological and behavioral processes that occur with a period 1 year Prepares animals for the changes in seasons b Circadian Rhythms Internal oscillations controlling cycles in the physiological and behavioral processes that occur with a period of 24 hours Plays a large part in sleep wake cycles i Based on internal clock that has a period T that runs over 24 hours ii T is determined by measuring activity and physiological patterns in constant darkness iii The slope of raster plots reveal T iv Humans have a circadian temperature cycle that peaks 6 hours before sleep and reaches a minimum 2 hours after sleep onset v Can be set by external cues called zeitgebers time givers 1 Light is one of the most zeitgebers vi The phase of the rhythm refers to when a specific physiological or behavioral event occurs in a 24 hour period 2 Phase Shifting a Advancing the onset of the event is called phase advance delaying the event is called phase delay Jet lag is an example of a phase shift East phase advance West phase delay b c Phase delays are easier to adjust to 3 Other Cells with Endogenous Rhythms a Cardiac Pacemaker cells b Respiratory neurons in the Medulla c Neurons in the Superachiasmatic nucleus of they Hypothalamus a Located at the base of the hypothalamus above the optic chiasm b Receives input from the retina via the retinohypothalamic tract c When the SCN is damaged animals have severely disrupted circadian patterns of temperature and activity d When the SCN are held in culture they maintain rhythmic patterns of neural activity 4 Melatonin a A hormone released by the pineal gland thought to help induce sleep b The SCN regulates melatonin release by the pineal gland c Release increases about 2 hours before the person s routine bedtime d Melatonin taken at other times of the day causes sleepiness when taken in the mid afternoon a phase advance is reported e The practice of taking melatonin to help with jet lag is under controversy 5 Sleep a Sleep is an active process b Sleep occurs in stages that can be differentiated by a Electrical activity in cortex b Rapid Eye Movements REM c Muscle tone in major limbs d Certain physiological events 6 Electrorncephalography EEG a Electrodes are placed on the scalp b Each electrode measures the summed electrical activity over time occurring in its vicinity c Different types of waveforms occur during different stages of sleep a Alpha waves low amplitude 9 12 Hz b Sleep spindles bursts of 12 14 Hz waves lasting for 5 seconds c K complex sharp high amplitude negative wave followed by a smaller more gradual positive wave d Delta waves large amplitude waves 1 2 Hz slow waves 7 Stages of Sleep a Awake and Alert desynchronized EEG b Awake and Relaxed pre sleep Presence of Alpha waves c Stage 1 desynchronized low amplitude EEF d Stage 2 appearance of sleep spindles and K complexes e Stage 3 appearance of 20 50 Delta waves f Stage 4 appearance of 50 Delta waves g REM a Postural and limb muscles are relaxed virtually paralyzed state b Eyes move bac and forth under the eyelids c Erections in males vaginal secretions in females d Associated with dreams of complex visual imagry and plots e A paradoxical sleep EEG indicates light sleep easily awaken from muscle inhibition indicates deep sleep 8 Dreams a Generally people only remember dreams BEFORE awakening b Memory details quickly decay without rehearsal c REM dreams tend to be longer on the average and generally involve more complex visual imagery and plots d Dream content is not connected to other dreams e Content is not related to external stimuli f Dreams involving explicit sexual content are relatively infrequent 9 Brain Structures for Arousal and Sleep a Pontomesencephalon between hind midbrain increases cortical arousal b Locus coeruleus increases the information storage during wakefulness suppresses REM Acetylcholine glutamate sleep norepinephrine c Basal forebrain a Excitatory cells excites thalamus and cortex increases learning attention shifts sleep from NREM to REM Acetylcholine b Inhibitory cells inhibits thalamus and cortex GABA d Hypothalamus increases arousal and maintains wakefulness Histamine Orexin e Dorsal raphe and pons Interrupts REM sleep Serotonin 10 PGO Waves Located in the hindbrain a b Bursts of activity starting at the pontine reticular formation and progressing to the lateral geniculate nucleus vision and then occipital cortex c Associated with the eye movements during REM 11 Sleep Deprivation a Prolonged sleep deprivation has led to a Increases in metabolic rate appetite and body temperature b Immune system failure c Decrease in brain activity d Irritability e Unpleasant mood f Tremors b Well practiced activities are less affected than those that require sustained attention Why you often have to re read pages right before bed c Delusions and hallucinations are only known to affect a subset of the population d The body will compensate by sleeping more when given the chance e The body enters the portion of sleep deprived more often when given the chance after deprivation 12 Why Sleep 13 Sleep Disorders a Energy Conservation b Restorative Functions depleted biochemicals c Memory Consolidation improve performance on newly formed tasks a Sleep Apnea the inability to breath while sleeping a Lasting a minute or longer b Person usually feels very tired during the day because of the interrupted sleep c Generally affects older people b Periodic Limb Movement repeated involuntary movement of the limbs during the initial hours of non REM sleep c Night Terrors a Occurs in children 6 10 yrs old b Happens in the initial hours of non REM sleep c Child screams sits up in bed in a state of terror and anxiety d This is not a reaction to a dream d Sleepwalking a Happens in the initial hours of non REM sleep b More common in children c Runs in families d Generally harmless Insomnia a Onset Insomnia trouble falling asleep b Maintenance Insomnia frequent awakenings during sleep trouble falling back e asleep f Narcolepsy c Termination Insomnia Waking up too early and failing to fall back asleep a Intrusion of REM during wakefulness b Onset 10 20 yrs c About 1 in 1000 Americans affected d Caused by an absence of orexin expressing cells in the hypothalamus e Traits i Sleep attack sudden attack of extreme sleepiness during the day ii Cataplexy sudden weakness in the muscles elicited by a sudden
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