Psyc 362Chapter8 text-Sleep and Biological RhythmsA Physiological and Behavioral Description of Sleep● Sleep is a behavior characterised by the insistent urge of sleepiness forcing us to seek out quiet, warm, comfortable places, and remain there for several hours. It is also a change of consciousness● Sleep laboratory: experimenter spends the night, prepares the sleeper for electrophysiological measurements by attaching electrodes to the scalp to monitor the electroencephalogram (EEG) and to the chin to monitor muscle activity, recorded as electromyogram (EMG). May also want to measure heart rate, breathing, and changes in skin’s ability to conduct electricity. ○ EEG shows two basic patterns of activity during wakefulness1. alpha activity: regular, medium frequency waves of 8-12 hz as produced when a person is resting quietly, not aroused or excited, and not engaged in strenuous mental activity. Mostly when eyes are closed2. Beta activity: irregular, mostly low amplitude waves of 13-30 hz to reflect the fact that many different neural circuits in the brain are actively processing information (showing desynchrony). This occurs when a person is alert/attentive to the environment or thinking actively○ Typical sleep: after stages 1-4, patient alternates through Rem and non-REM sleep, each cycle about 90 mins long (8 hour sleep contains about 4-5 periods of REM sleep)■ stage 1 (a transition stage between sleep and wakefulness) of sleep marked by the presence of theta activity (3.5-7.5 hz), which indicates more synchronized firing of neurons in the neocortex. ■ stage 2 sleep with EEg generally irregular containing periods of theta activity, sleep spindles (short bursts of 12-14 Hz between 2-5 times a minutes during stages 1-4) and K complexes (sudden sharp waveforms,usually found only in stage 2, that play a role in memories. Often spontaneous, one per minute, can be stimulated by noise. Are isolated periods of neural inhibition).■ stage 3 sleep is signaled by start of high amplitude delta activity (slower than 3.5 Hz). About 20-50% is delta. stage 4 sleep has more than 50% delta. Slow wave EEG activity predominates in these stages so collectively referred to as slow-wave sleep.● Most important feature of slow-wave activity is the presence of slow oscillations of less than 1Hz, each consisting of one high-amplitude wave of slightly less than 1Hz. The wave is biphasic, consisting of a down state (first part, a period of inhibition during which neurons in the neocortex are absolutely silent and the neocortical neurons are able to rest. Its an inhibitory hyperpolarization silent phase) and an up state (second part, a period of excitation when neurons briefly fire at a high rate. its an excitatory depolarizing phase when neurons fire at high rates).■ Stage 5/REM sleep involves a much more desynchronized EEG with a sprinkling of theta waves, similar to stage 1, plus rapid darting of the closed eyes (Rapid Eye Movement). There is also a loss of muscle tone, and a seeming paralysis of the body, minus some twitching, because most of our spinal and cranial motor neurons are strongly inhibited (but the brain is very active). “Dreaming” occurs in this stage. ● TABLE 8.1Disorders of SleepInsomnia: a difficulty falling asleep after going to bed or after awakening during the night. ● hard to identify due to unreliability of self-reports, but often treated without direct clinical evidence. Most individuals underestimate the amount of time they spend sleeping. ● Many traditional drugs put people to sleep with drowsiness, but made them groggy and unable to concentrate the next day. The goal should be to make individuals feel more refreshed the next day. ● Many people are often sleep-deprived due to the demands of their daily schedules keeping them up/waking them up early. This can lead to increased risk of obesity, diabetes, and cardiovascular disease● Sleep apnea is caused by an inability to sleep and breathe at the same time; individuals fall asleep and then cease to breathe. (nearly all people have occasional episodes of sleep apnea, but not to the extent that it interferes with sleep. Most cases caused by an obstruction of the airway, which can be surgically fixed or relieved with breathing device that keeps airway open. Narcolepsy: a neurological disorder where one sleeps at inappropriate times. ● sleep attack: an overwhelming urge to sleep that can happen at any time but occurs most often under boring conditions. They generally last for 2-5 minutes, and the person wakes up feeling refreshed. ● cataplexy: during a cataplectic attack, one sustains varying amounts of muscle weakness. one may become completely paralyzed and slump down to the floor, and maylie there fully conscious for a few seconds or minutes,while still able to breathe and control eye movement. (muscular paralysis of REM sleep occurs inappropriately) ○ usually caused by strong emotional reactions or by sudden physical effort. Common situations: attempting to discipline one’s children and making love. So, patients try to avoid thoughts and situations likely to evoke strong emotions that are likely to trigger a cataplectic attack. ● sleep paralysis: symptom where paralysis occurs just before onset of sleep or upon waking in the morning. Can be snapped out by being touched or hearing someone call his or her name (similar to REM sleep). ○ Hypnagogic hallucinations can occur during a sleep paralysis in which one hasa vivid dream while lying there awake. it’s often alarming or even terrifying. ● Hereditary with gene found on chromosome 6, but strong environmental influence.○ The lateral hypothalamus contains the somas of all the neurons that secrete this peptide (hypocretin/orexin), and the destruction of orexin appears to be a mutation responsible for narcolepsy. orexin plays a role in control of metabolism and eating. THere are two orexin receptors and the mutation involves the orexin B receptor.○ Appear to be caused by a hereditary autoimmune disorder, such that they are born with orexinergic neurons that are attacked by the immune system, beginning narcolepsy. REM Sleep Behavior Disorder: a neurological disorder in which the person doesn’t become paralyzed during REM sleep so they act out their dreams. (NOT Sleep Walking)● Appears to be a neurodegenerative disorder, with opposite symptoms of cataplexy: rather than exhibit paralysis outside REM sleep, patients with this fail