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Topic 7 States of Consciousness: Circadian Rhythms, Sleep & Dreams Topic of focus Stages of sleep Why do we sleep? Biological clocks Sleep & Consicousness Physiological mechanism of Sleep and waking Consciousness • Consciousness can take many forms, while other mental processes occur simultaneously outside our awareness • Consciousness changes in cycles that correspond to our biological rhythms and the patterns of stimulation in our environment Everything of which we are aware at any given time o o o o Thoughts Feelings Sensations External stimuli Altered State of Consciousness o Changes in awareness produced by o o o o Sleep Meditation Hypnosis Drugs WHY DO WE NEED TO SLEEP? Why do we sleep? Recuperation theories Sleep is needed to restore homeostasis Wakefulness causes a deviation from homeostasis Circadian theories Sleep is the result of an internal timing mechanism Sleep evolved to protect us from the dangers of the night Comparative Analysis of Sleep All mammals and birds do it – must have an important function Not a special higher-order human function Not necessarily needed in large quantities No clear relationship between species’ sleep time and activity level BIOLOGICAL CLOCK The Influences of Circadian Rhythms o Environmental Cues o The ebb and flow of circadian rhythms is not strictly biological; environmental cues also play a part o Bright light o especially sunlight o Sleep-wakefulness cycle o Daily fluctuations of body temperature o Sleep is best when body is at lowest temperature (97-97.5) The Influences of Circadian Rhythms o Control of seasonal rhythms o Pineal Gland o A gland attached to the dorsal tectum; produces melatonin and plays a role in circadian and seasonal rhythms. o Secretes melatonin from dusk until just before dawn o Does not secrete melatonin during daylight hours o Melatonin o A hormone synthesized from serotonin in the pineal gland o Secreted during the night by the pineal body; o Melatonin levels display circadian rhythms controlled by the SCN o plays a role in circadian and seasonal rhythms. o Melatonin is not a sleep aid, but may be used to shift circadian rhythms Disruptions in Circadian Rhythms Jet lag o When traveling, you reach your destination at a time when it is daylight there, but it would have been time to go to sleep at the place you started o Can produce memory deficits that may be permanent o Supplemental melatonin has been shown to be an effective treatment for relapses of psychiatric disorders induced by jet lag o Zeitgebers are accelerated or decelerated o Research indicates that frequent flyers, such as this airline employee, are just as likely to suffer from jet lag when crossing several time zones as travelers who are on their first intercontinental journey. Disruptions in Circadian Rhythms Shift work o When people work during the night and sleep during the day o Shift workers average 2 to 4 hours less sleep than nonshift workers of the same age o Subjective night o The time during a 24-hour period when body temperature is lowest and when the biological clock is telling a person to go to sleep o During subjective night, energy and efficiency are at their lowest point, reaction time is slowest, productivity is diminished, and industrial accidents are significantly higher Zeitgebers unchanged, but sleep-wake cycle must be altered o Rotating work schedules forward from days to evenings to nights makes adjustment easier because people find it easier to go to bed later and wake up later than the reverse o Modafinil o A wakefulness drug that will help people remain alert without the side effects of stimulants such as caffeine Can the effects be prevented or minimized? o Both produce a variety of deficits o Can the effects be prevented or minimized? Reducing Jet Lag Gradually shift sleep-wake cycle prior to travel Administer post-flight treatments to promote the needed shift Phase advance following east-bound travel with intense light early in the morning Hamster studies suggest a good early morning workout may also help Can the effects be prevented or minimized? Reducing the Effect of Shift Changes Schedule phase delays, rather than phase advances Move from current schedule to one that starts later It is easier to stay up later and get up later than to retire and arise earlier Phase advances are harder, explaining why east-bound travel tends to be more problematic Shift workers who temporarily reside at their work places, such as workers on offshore oil rigs, appear to adjust more easily to the demands of night work than those who live at home Exposure to appropriately timed bright light or even light of medium intensity has been found to reset young adults’ biological clocks and improve their performance The Influences of Circadian Rhythms Disruptions in Circadian Rhythms o Subjective night o The time during a 24-hour period when the biological clock is telling a person to go to sleep. o Energy and efficiency are at their lowest points o Reaction time is slowest o Productivity is diminished o Industrial accidents are higher o Daylight savings time in spring is associated with short term 6.5% increase in accidental deaths. o Work schedules o Moving work schedules forward from days to evenings to nights makes adjustment easier o Rotating shifts every three weeks lessens the effect on sleep The Influences of Circadian Rhythms o Circadian Rhythm o A daily rhythmical change in behavior or physiological process. o About a day o Regular fluctuation from high to low points of certain bodily functions and behaviors o Sleep debt o Deficiency caused by not getting the amount of sleep that one requires for optimal functioning o Affects psychological functions of o o o o o o o Blood pressure Heart rate Appetite Secretion of hormones and digestive enzymes Sensory acuity Elimination Body’s response to medication The Influences of Circadian Rhythms o Suprachiasmatic nucleus (SCN) o A nucleus, situated atop the optic chiasm, in the brain’s hypothalamus that control the timing of circadian rhythms o It contains a biological clock responsible for organizing many of the body’s circadian rhythms. o Lesions do not reduce sleep time, but they abolish its circadian periodicity o Exhibit activity that can be entrained by the light-dark cycle o Transplant SCN, transplant sleep-wake cycle o Melanopsin o A photopigment present in ganglion cells in the retina whose axons transmit information to the SCN, the thalamus, and the olivary pretectal nuclei. o Zeitgebers o A stimulus (usually the light of dawn) that resets the biological clock responsible for circadian rhythms. o Intergeniculate leaflet (IGL) o A part of the lateral geniculate nucleus that receives information from the retina and projects to the SCN; terminals release neuropeptide Y at the SCN Stages of sleep Sleep o Understanding of sleep increased by the study of o o o o o Brain waves Eye movements Chin muscle tension Heart rate Respiration rate Electro-oculogram (EOG) An electrical potential from the eyes, recorded by means of electrodes placed on the skin around them; detects eye movements. Electromyogram (EMG) An electrical potential recorded from an electrode placed on a muscle. 3 Physiological Measures of Sleep By means of Electroencephalogram (EEG) “brain waves” By means of EOG Eye movements seen during rapid eye movement (REM) sleep By means of EMG Loss of activity in neck muscles during some sleep stages Sleep Polysomnogram o Provides brain wave sleep recordings o Outlined REM and NREM sleep patterns EEG Beta activity Irregular electrical activity of 13–30 Hz recorded from the brain; generally associated with a state of arousal. Alpha activity A smooth electrical activity of 8–12 Hz recorded from the brain; generally associated with a state of relaxation Eyes closed, preparing to sleep Theta activity EEG activity of 3.5-7.5 Hz that occurs intermittently during early stages of slow-wave and REM sleep. Delta activity Regular, synchronous electrical activity of less than 4 Hz recorded from the brain; occurs during the deepest stages of slow-wave sleep. Stages of Sleep o Stage 1 o A transition period of drowsiness between waking and sleeping. o Sleep spindles occur o Stage 2 o Somewhat more deeply asleep. o Delta waves slight o Stage 3 o Slow wave sleep begins o Delta waves reach 20%. o Stage 4 – Delta waves reach nearly 100%. Sleep Cycle & EEG Stage 1 similar to awake EEG, but slower low-voltage, high-frequency EEG voltage increases and frequency decreases as one progresses from stage 1 through 2, 3, and 4 Stage 2 – characterized by K complexes – large negative waves Sleep spindles – burst of 12-14 Hz waves Stages 3 and 4 – delta waves, large and slow Progress to stage 4 sleep and then retreat to stage 1 Sleep Cycle & EEG Emergent stage 1 differs from initial stage 1 REMs Loss of body core muscle tone Progress through sleep stages in 90 minute cycles More time spent in emergent stage 1 as night progresses Emergent stage 1 sleep = REM sleep Non-REM (NREM) sleep = all other stages Stage 3 + 4 = slow-wave sleep (SWS) During REM: REMs, loss of core muscle tone, lowamplitude/high-frequency EEG, increased cerebral and autonomic activity, muscles may twitch NREM Sleep o Non-rapid eye movement sleep. o 1. 2. 3. 4. Four sleep stages Lightest sleep Mid-sleep Deep sleep Deepest sleep o Heart and respiration slow and regular o Little body movement o Blood pressure and brain activity at lowest points of 24 hour period. REM Sleep Non-REM sleep All stages of sleep except REM sleep. REM sleep A period of desynchronized EEG activity during sleep, at which time dreaming, rapid eye movements, and muscular paralysis occur. 80% of awakenings from REM yield reports of story-like dreams Slow-wave sleep Non-REM sleep, characterized by synchronized EEG activity during deeper stages. Basic rest-activity cycle A 90-minute cycle (in humans) of waxing and waning alertness, controlled by a biological clock in the caudal brain stem; controls cycles of REM sleep and slow-wave sleep. REM Sleep o Rapid eye movement sleep o Called “active sleep” o 20-25% of a night’s sleep o Internally: o Intense brain activity o Brain metabolism increases o Brain temperature rises rapidly o Epinephrine release leads to increases in o Blood pressure o Heart rate o respiration o Externally: o Body appears calm o Large muscles become paralyzed o Eyes dart around o Dreaming occurs in 80% of people o The brain conducts o Consolidation of learning (all night studying doesn’t help) o perceptual skills increase after 8-10 hours of sleep o Memory consolidation REM Rebound o The increased amount of REM sleep that occurs after REM deprivation o Intensity of REM sleep increases o Those with Sleep Deprivation o Proceed more rapidly into REM as REM deprivation increases o More time spent in REM when deprivation is over o Often associated with unpleasant dreams or nightmares o Alcohol, amphetamines, cocaine, and LSD use suppress REM sleep results in REM rebound o Withdrawal results in REM rebounds REM rebound suggests that REM sleep serves a special function Purpose of REM? Necessary for mental health Inconsistent with the effects of tricyclic antidepressants – block REM Necessary for maintenance of normal levels of motivation Necessary for processing of memories No clear purpose Default Theory of REM REM serves no critical function One can’t stay continuously in non-REM sleep, so we switch between REM and wakefulness When bodily needs exist – wake up No immediate needs – REM No REM rebound seen when lost REM periods replaced with 15-mins awake Variations in Sleep o Infants and young children o have the longest sleep time o Have the highest of REM and slow wave sleep o Ages 6-puberty o Most consistent sleepers and wakers o Sleep and awake same time daily o Adolescents o Sleep patterns are influenced by their schedules o Sleep longer when no schedule conflicts o Poor sleep may contribute to poor school performance Effects of Sleep Deprivation o Causes o o o o o Difficulty concentrating Attention lapse General irritability Decreases cognitive functioning Impairs learning Recuperation theories predict: Long periods of wakefulness will result in disturbances Disturbances will get worse as deprivation continues After deprivation, much of the missed sleep will be regained What does the research indicate? Studies of Sleep Deprivation in Humans Does sleep loss affect your performance? We tend to be poor judges of the effects of sleep deprivation on our performance 3-4 hours of deprivation in one night Increased sleepiness Disturbances displayed on written tests of mood Perform poorly on tests of vigilance 2-3 days of continuous deprivation Experience microsleeps, naps of 2-3 seconds Effects on complex cognitive function, motor performance, and physiological function are less consistent Sleep-Deprivation Studies with Lab Animals Carousel apparatus used to deprive rats of sleep When the experimental rat’s EEG indicates sleep, the chamber floor moves – if the rat does not awaken, it falls into water Yoked controls – subjected to the same floor rotations Experimental rats typically die after several days Postmortem studies reveal the extreme stress experienced by the experimental rats Carousel apparatus Theories of Sleep Function o Restorative theory, holds that being awake produces wear and tear on the body and brain, and sleep serves the function of restoring the body and mind. o Circadian theory of sleep is based on the premise that sleep evolved to keep humans out of harm’s way during the dark of night and possibly from becoming prey of some nocturnal predator. Sleep Disorders - Parasomnias o Somnambulism (sleepwalking) o occurs during partial arousal from stage 4 sleep. o Sleep terror o happens during partial arousal from stage 4 sleep o usually begins with a piercing scream. o Nightmares o are frightening dreams that occur during REM sleep. o Somniloquy (Sleeptalking) o occurs during any sleep stage o is more frequent among children. Major Sleep Disorders o Insomnia A sleep disorder characterized by Disorders of sleep initiation and maintenance o Difficulty falling or staying asleep o Waking too early o Sleep that is light, restless, or of poor quality Symptoms can lead to distress and impairment in daytime functioning o Hypersomnia o Disorders of excessive sleep or sleepiness Major Sleep Disorders o Sleep apnea Periods during sleep when breathing stops and the individual must awaken briefly in order to breathe o 2 types 1. Caused by muscle spasms or atonia 2. Failure of the CNS to stimulate breathing Most commonly seen in males, the overweight, and in the elderly The major symptoms are excessive daytime sleepiness and extremely loud snoring, often accompanied by snorts, gasps, and choking noises Alcohol and sedatives aggravate the condition Can lead to chronic high blood pressure, heart problems, and even death Neuroscientists have also found that it can cause mild brain damage The interrupted sleep experienced by individuals with this disorder affects cognitive as well as physiological functioning Major Sleep Disorders o Narcolepsy o Also a form of hypersomnia o Characterized by excessive daytime sleepiness and repeated brief uncontrollable attacks of daytime REM sleep, usually lasting 10 – 20 minutes o An incurable sleep disorder o Cataplexy – loss of muscle tone while awake o Sleep paralysis – paralyzed while falling asleep or upon waking o Hypnagogic hallucinations – dreaming while awake o Appears to be an abnormality in the mechanisms that triggers REM o Dreaming and loss of muscle tone while awake – suggest REM intruding into wakefulness o REM without atonia – able to act out dreams – possibly caused by damage to the nucleus magnocellularis or its output What Other Forms Can Consciousness Take? • An altered state of consciousness • A mental state other than ordinary waking consciousness, such as sleep, meditation, hypnosis, or a drug-induced state • occurs when some aspect of normal consciousness is modified by mental, behavioral, or chemical means • Hypnosis • Induced state of altered awareness, characterized by heightened suggestibility and deep relaxation • Meditation • Form of consciousness change induced by focusing on a repetitive behavior, assuming certain body positions and minimizing external stimulation • Psychoactive drug states • Chemicals that affect mental processes and behavior by their effects on the nervous system Hypnosis A procedure through which one person, thehypnotist, uses the power of suggestion to induce changes in a person’s: o o o o Thoughts FeelingsSensations Perceptions Behavior Hypnotizability – Degree to which an individual is responsive to hypnotic suggestions o 80-95% of people are hypnotizable to some degree o About 5% can reach deepest levels Misconceptions About Hypnosis o Hypnotized people are under the complete control of the hypnotists and will violate their moral values o People can demonstrate superhuman strength and perform amazing feats under hypnosis o Subjects are not stronger or more powerful under hypnosis o Memory is more accurate under hypnosis o Pseudomemories – false memories constructed through guidance. o People under hypnosis will reveal embarrassing secrets o Hypnosis is not like a truth serum o Subjects can keep secrets or lie under hypnosis o People under hypnosis can relive an event that occurred when they were children and can function mentally as if they were that age. Careful reviews of studies on hypnotic age regression have found no evidence to support this claim Meditation A group of techniques that involve o focusing attention on o o o o o o o o an object a word one’s breathing, one’s body movements An effort to block out all distractions Enhance well-being Achieve an altered state of consciousness. Includes: Yoga, Zen, and transcendental meditation Yoga A meditator typically assumes a cross-legged position known as the lotus and gazes at a visual stimulus Zen The individual counts breaths or concentrates on the breathing process o Can be helpful with physical and psychological problems o Lower blood pressure o Learn how to control emotions Physiological Mechanisms of Sleep and Waking Types of neurotransmitter involved 1. Acetylcholine One of the most important neurotransmitters involved in arousal. Two groups of acetylcholinergic neurons located in the pons and basal forebrain. They produce activation and cortical desynchrony when they are stimulated. 2. Norepinephrine Catecholamine agonists produce arousal and sleeplessness; effects appear to be mediated by the locus coeruleus in the dorsal pons. 3. Serotonin (5-HT) Appears to play a role in activating behavior; almost all of the brain’s serotonergic neurons are found in the raphe nucleus. These neurons are located in the medullary and pontine regions of the brain. 4. Histamine A neurotransmitter implicated in the control of wakefulness and arousal; a compound synthesized from histidine, an amino acid. Physiological Mechanisms of Sleep and Waking Neural control of arousal Locus coeruleus A dark color group of noradrenergic cell bodies located in the pons near the rostral end of the floor of the fourth ventricle; involved in arousal and vigilance. Raphe nucleus A group of nuclei located in the reticular formation of the medulla, pons, and midbrain, situated along the midline; contains serotonergic neurons. Tuberomammillary nucleus A nucleus in the ventral posterior hypothalamus, just rostral to the mammillary bodies; contains histaminergic neurons involved in cortical activation and behavioral arousal. Hypocretin A peptide also known as orexin, produced by neurons whose cell bodies are located in the hypothalamus; their destruction causes narcolepsy. Physiological Mechanisms of Sleep and Waking Neural control of slow-wave sleep Ventrolateral preoptic area (VLPA) A group of GABAergic neurons in the preoptic area whose activity suppresses alertness and behavioral arousal and promotes sleep. Destruction of this area has been reported to result in total insomnia, coma, and eventual death in rats. Physiological Mechanisms of Sleep and Waking Neural control of REM sleep PGO wave (pontine, geniculate, occipital): Bursts of phasic electrical activity originating in the pons, followed by activity in the lateral geniculate nucleus and visual cortex, a characteristic of REM sleep. Psychoactive Drugs Any substance that has powerful effects on the brain and alters: o Consciousness Psychoactive drugs are: o Controlled substances o approved for medical use o Illicit drugs o Mood o drugs that are illegal o Perception o Over-the counter drugs o Thought o Antihistamines o Decongestants Hallucinogens o Herbal preparations Depressants Opiates Stimulants o Certain foods o chocolate How Drugs Affect The Brain All physical pleasure has a neurological basis: Brought about by increase of dopamine in limbic system known as the Nucleus Accumbens A surge of dopamine has a o reward and motivational effects o produced by psychoactive drugs. The effects of drugs cascades down involving the brain’s entire neurotransmitter system. How Drugs Affect The Brain Hallucinogens Alter perceptions of the external environment and inner awareness (also called psychedelics) • Mescaline • LSD • PCP • Cannabis How Drugs Affect The Brain Opiates Highly addictive; produce a sense of well-being and have strong pain-relieving properties Heroin, Morphine, Heroin and Methadone o Mimic the effects of the brain’s own endorphins o Chemicals in the brain with pain relieving properties o Produce feelings of well-being o Useful in pain management How Drugs Affect The Brain Depressants Slow down mental and physical activity by inhibiting transmission of nerve impulses in the central nervous system o Alcohol o Barbiturates o Benzodiazepines (Tranquilizers) oValium and Librium o Act on GABA receptors to produce a calming, sedating effects. o Useful in reducing a patient’s nervousness prior to undergoing a medical procedure. How Drugs Affect The Brain Stimulants Arouse the central nervous system, speeding up mental and physical responses o Mimics the effects of epinephrine o The neurotransmitter that triggers the nervous system o Caffeine o Nicotine o Amphetamines o Cocaine o MDMA (ecstasy) o Benefits include suppression of hunger and digestion o Often found in “diet pills” How Drugs Affect The Brain Amphetamines affect the parts of the brain that control attention and concentration, as well as the nucleus accumbens. o Stimulate the release of dopamine in frontal cortex improving attention and concentration This helps explain why these stimulants are useful in the treatment of attention problems in school children (i.e. ADHD). Substance Abuse A continued use of a substance after several episodes in which use of the substance has negatively affected an individual's work, education, and social relationships. o People progress from substance “use” to “abuse” by o The physical pleasure o Genetically based differences in people’s responses to drugs o e.g. People who drink more to “feel the effect” are more likely to become alcoholics o Personality and social factors o e.g. Impulsiveness o Stress related variables o e.g. Victim of child abuse or domestic violence o Social and cultural factors o e.g. Associating with peers who abuse drugs Drug Dependence Commonly called “addiction” o Physical drug dependence o A compulsive pattern of drug use in which o the user develops a drug tolerance o coupled with unpleasant withdrawal symptoms when the drug is discontinued. o Drug Tolerance o A condition in which the user becomes o progressively less affected by the drug o must take increasingly larger doses to maintain the same effect or high. Drug Dependence o Withdrawal Symptoms o The physical and psychological symptoms that occur when a regularly used drug is discontinued o Usually the exact opposite of the effects produced by the drugs o Symptoms terminate when drug is taken again. o Psychological Drug Dependence o A craving or irresistible urge for the drug’s pleasurable effects. o More difficult to combat than physical dependence o Drugs that may not be physically addictive may be due to psychological dependence o Learning processes (classical conditioning) are important elements in development and maintenance of psychological dependence The Behavioral Effects of Psychoactive Drugs DETAILED DESCRIPTION The Behavioral Effects of Psychoactive Drugs o Stimulants o Speed up activity in the central nervous system o Increase blood pressure, pulse rate, respiration rate, and reduce cerebral blood flow o o o o Suppress appetite Help ‘feel’ more awake and energetic Also called “uppers” High doses make people “feel” more o Nervous o Jittery o Restless o Shaky or trembling o Interfere with sleep Stimulants Continued o Caffeine o Coffee, tea, cola, chocolate, and 100+ prescriptions and overthe-counter drugs o May improve visual acuity o Withdrawal for moderate to heavy use induces o o o o Nervousness Instability Headaches, drowsiness Decreased alertness o EEG’s confirm withdrawal effects on the brain o Significant increases in blood pressure and velocity of blood flow in all four cerebral arteries o Increase in slower brain waves causing decreased alertness and drowsiness Stimulants Continued o Nicotine o o o o o Increases alertness Suppresses appetite in some people Highly addictive Hypnosis treatments are largely ineffective Nicotine patches help 1 in 5 smokers quit Stimulants Continued o Amphetamines o o o o o o Increase arousal Relieve fatigue Improve alertness Suppress appetite Give a rush of energy Stimulate the release of dopamine in frontal cortex improving attention and concentration o (helping with ADHD ) o Can cause confused and disorganized behaviors o o o o Extreme fears and suspiciousness Delusions and hallucinations Aggressive and antisocial behaviors Manic behaviors and paranoia Stimulants Continued o Cocaine o Stimulant derived from coca leaves o Can be sniffed, injected, or smoked as crack o Euphoria is followed by an equally intensive crash marked by o o o o Depression Anxiety Agitation A powerful craving for more drug o Stimulate the reward (pleasure) pathways in brain o Reward pathways fail with continued use so no pleasure is felt except when taking the drug o Main withdrawal symptoms are psychological o Inability to feel pleasure o Strong desire for more drug Depressants o Alcohol o Depresses central nervous system o Increased drinking causes o Slurred speech o Poor coordination o Staggering o Impaired depth perception o Men tend to become aggressive and sexually aroused yet less able to perform sexually o Decreases ability to form new memories o Drinker’s expectations of alcohol effects also contribute to alcohol’s effect Depressants o Barbiturates o Depress central nervous system o Act as sedative or sleeping pill dependent on amount taken o Abusers become o o o o o Drowsy and confused Thinking and judgment suffer Coordination and reflexes are affected Can kill if taken in overdose (as little as three times regular dose) When taken with alcohol are potentially fatal o Minor Tranquilizers o Benzodiazepines (valium, Librium, dalmane, xanax) o Abuse is associated with o temporary and permanent impairment of memory and other cognitive functions Hallucinogens (psychedelics) o Drugs that alter and distort perceptions of time and space, alter mood, produce feelings of unreality, and cause hallucinations. o Marijuana (THC tetrahydrocannabinol) o o o o o o o o o Produces a high Remains in the body for days or even weeks Impairs attention and coordination Slows reaction time after intoxication feeling has passed Interferes with concentration, logical thinking, and ability to form new memories Produces fragmentation in thought Confusion in remembering recent occurrences Chronic use associated with loss of motivation, general apathy, and decline in school/work performance Medical benefits include treatment of glaucoma, controlling nausea in cancer patients, and improving appetite and controlling weight loss in AIDS patients Hallucinogens (psychedelics) o LSD (Llysergic Acid Diethylamide) o Often referred to as “acid” o A “trip” lasts 10-12 hours and produces o extreme perceptual and emotional changes o Visual hallucinations o Feelings of panic o Bad “trips” are associated with o Accidents, death, or suicide o Flashbacks or ‘hallucinogen persisting disorder’ o Designer Drugs o o o o Mimic pleasurable effects of other drugs STP and Ecstasy Derived from amphetamines Have hallucinogenic and stimulant effect