February 23 2015 Chapter 4 Consciousness Textbook Notes Section 1 What is Consciousness 4 1 What does it mean to be conscious and are there different levels of consciousness Consciousness is a person s awareness of everything awareness of everything that is going on at any given moment Most waking hours are spent in waking consciousness Altered states of consciousness are shifts in the quality or pattern of mental activity Section 2 Sleep 4 2 Why do people need to sleep and how does sleep work Sleep is a circadian rhythm lasting 24 hours and is a product of the activity of the hypothalamus the hormone melatonin the neurotransmitter serotonin and body temp Adaptive theory states that sleep evolved as a way to conserve energy and keep animals safe from predators that hunt at night Restorative theory states that sleep provides the body with an opportunity to restore chemicals that have been depleted during the day as well as the growth and repair of cell tissue Average amount of sleep needed by adults is about 7 to 9 hours within each 24 hour period The Rhythms of Life Circadian Rhythms The sleep wake cycle is ultimately controlled by the brain specifically by an area within the hypothalamus the tiny section of the brain that influences the glandular system The Role of the Hypothalamus The Mighty Mite Melatonin a hormone normally secreted by the pineal gland hoping to sleep better and perhaps even slow the effects of aging The release of melatonin is influenced by a structure deep within the tiny hypothalamus in an area called the suprachiasmatic nucleus internal clock tells people when to wake up and when to fall asleep Serotonin producing neurons are most active during wakefulness less active during SWS and relatively inactive during REM Some serotonin receptors are excitatory and others are inhibitory For example some receptors facilitate some stages of sleep while others inhibit other stages The suprachiasmatic nucleus as part of the hypothalamus controls body temp The higher the body temp the more alert people are the lower the temp the sleepier they are When people are asleep at night their body temp is at lowest level As body temp drops sleep begins The importance of sleep and the price of not sleeping More complex task such as math problems suffer less than these simple task bc people know they must concentrate on a complex task Nearly 50 of an infant s sleep is REM compared to only about 20 for a normal healthy adult February 23 2015 Consequences of poor nights sleep and sleep deprivation are increased risk of insulin resistance which can lead to diabetes and even possible delays in the onset of puberty Sleep is important for forming memories Studies show physical changes in the brain that occur when we form memories are strengthened during sleep and particularly so for children This memory effect is no doubt due at least in part to the finding that sleep enhances the synaptic connections among neurons thus increasing the plasticity of the brain the brain s ability to adapt to experiences Theories of sleep If active in a hunting hour the prey is in a safe place sleeping and conserving energy in order to remain unharmed If the adaptive theory is true then one would expect prey animals to sleep mostly at night and for shorter periods of time than predator animals you would also expect that predators could sleep in the daytime virtually as much as they want The Restorative Theory of Sleep Brain elasticity is enhanced by sleep evidence supports most bodily growth and repair occur during the deepest stages of sleep when enzymes responsible for these functions are secreted in higher amounts Adaptive theory explains why people sleep when they do and restorative theory explains why people need to sleep What Is Consciousness People s awareness of everything that is going on around them at any given moment thoughts sensations and feelings much of the day is spent in waking consciousness where these are clear and organized Altered states of consciousness occur when there is a shift in the quality or pattern of mental activity as compared to waking consciousness alertness thought content and focus can vary greatly Sleep one of the body s daily circadian biological rhythms sleep wake cycle controlled by the brain including the hypothalamus and the neurotransmitter serotonin hypothalamus contains the suprachiasmatic nucleus SCN SCN is sensitive to light influences pineal gland s secretion of melatonin melatonin sleepiness light through eyes relayed to SCN SCN signals pineal gland to stop producing melatonin melatonin alertness sleepiness SCN also influences body temperature temperature sleepiness people can live without sleep for a while can t live without it altogether sleep deprivation can lead to serious changes in body and mental functioning February 23 2015 amount of sleep needed ranges from 4 10 hours most people need 7 9 hours every 24 hours adaptive theory of sleep suggests sleep is a product of evolution sleep has evolved to avoid the active time of predators restorative theory of sleep suggests sleep is vital to the physical health of the body body growth and repair occur during the deepest stages of sleep 4 3 What are the different states of sleep including the stage of dreaming and its importance N1 NREM Stage 1 sleep is light sleep Theta waves slower and larger than alpha waves N2 NREM Stage 2 sleep indicated by presence of sleep spindles last a second or two bursts of activity on the EEG theta waves are predominant in this stage If people are awakened in this stage they will be aware that they were sleeping N3 NREM Stage 3 and 4 highlighted by the first appearance of delta waves the slowest and largest waves and the body is at its lowest level of functioning deepest stage of sleep slow wave sleep SWS or simply deep sleep During this stage of sleep growth hormones often referred to as GH are released from pituitary gland and reach their peak Deep sleep time body growth occurs REM sleep occurs 4 or 5 times a night replacing N1 after a full cycle through N1 N3 and then ascending back to lighter stages of sleep It is accompanied by paralysis of the voluntary muscles but rapid movement of the eyes Electroencephalograph EEG allows scientists to record the brain wave activity as a person passes through the various states of sleep and determine type of sleep person has entered In REM sleep voluntary muscles are inhibited making person in REM sleep move very little Beta waves