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Unformatted text preview: Consciousness and Sleep Consciousness : our subjective experience of the world, our bodies, and our mental perspective Your awareness and perspective of yourself and the world around you • When we sleep we depart from our conscious state • During sleep we are no longer aware of our surroundings & our bodies. • We engage in dreams in which we are aware of who we are, but often engage in impossible and fantastic activities Sleep • We spend one-third of our lives sleeping • Sleep is central to our health and development • Some theories suggest that sleep is crucial for memory consolidation, immune system, neural development, survival by conserving our energy Sleep-wake cycles Circadian rhythm : cyclical changes that occur on a roughly on 24-hourly basis in many processes Hormonal release, brain waves, body temperature fluctuate within the 24 hours Biological clock : term for the suprachiasmatic nucleus of the hypothalamus that’s responsible for controlling our levels of alertness. Makes us feel drowsy at different times during the day and night, production of melatonin is increased • Most people need about 7-10 hours per night • Newborns require 16 hours • People who carry DEC2 mutation gene (less than 1%) need only 6 hours • College students may need 9 hours to feel rested and not need a nap the next day • Few nights of sleep deprivation will create ‘sleep debt’ • Constant sleep deprivation increases risk of depression, inability to learn new information or pay attention, weight gain, high blood pressure, diabetes, heart problems Stages of Sleep • When we sleep our brain doesn’t just shut off • EEG recordings done during sleep identify different patterns of brain activity associated with different stages of sleep • Overall each night we repeatedly go through 5 states of sleep Stage I Sleep • Very light sleep, lasts 5 to 10 min • Sometimes not sure if you were asleep or awake • Brain activity powers down by 50 percent • Can experience hypnagogic images : dreamlike images • Jerks of the limbs Stage I I Sleep • Deeper sleep • Brain activity slows down further • Slowed heart beat • Lowered body temperature • Muscle relaxation • Eye movements cease • We spend as much as 65% of our sleep in stage I I Stage I I I and I V Sleep • Deeper stages of sleep • To feel rested we need to experience these deeper stages throughout the night • Children spend 40% of their sleep in stages I I I and IV • Great difficulty to be awaken Sleep V Stage • We return to stage I I sleep before stage V • Brain activity increases dramatically • Rapid eye movement (REM) sleep : stage of sleep which the brain is most active and during which vivid dreaming most often occurs • Increased heart rate and blood pressure • Rapid and irregular breathing • Occupies 20-25% of the night’s sleep • Lasts 10-20 min and the sleep cycle starts up again • Amount of time we spend in REM sleep increases with each cycle, each night we...
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