Normal Awake and Sleep States PDF

# Normal Awake and Sleep States ## Circadian Cycle - In the absence of outside information about light and dark periods, humans show a circadian cycle, including awake and sleeping states closer to 25 hours than to 24 hours in length. ## Awake State - Beta and alpha waves characterize the elect...

# Normal Awake and Sleep States ## Circadian Cycle - In the absence of outside information about light and dark periods, humans show a circadian cycle, including awake and sleeping states closer to 25 hours than to 24 hours in length. ## Awake State - Beta and alpha waves characterize the electroencephalogram (EEG) of the awake individual. - Beta waves over the frontal lobes are commonly seen with active mental concentration. - Alpha waves over the occipital and parietal lobes are seen when a person relaxes with closed eyes. - Sleep latency (period of time from going to bed to falling asleep) is typically less than 10 minutes. ## Sleep State - During sleep, brain waves show distinctive changes. - Sleep is divided into rapid eye movement (REM) sleep and non-REM sleep, which consists of stages 1, 2, 3, and 4. - Mapping the transitions from one stage of sleep to another during the night produces a structure known as sleep architecture. - Sleep architecture changes with age. The elderly often have poor sleep quality because aging is associated with reduced REM sleep and delta sleep (stages 3-4 or slow wave) and increased nighttime awakenings, leading to poor sleep efficiency (percent of time actually spent sleeping per percent of time trying to sleep). - Sedative agents, such as alcohol, barbiturates, and benzodiazepines, are associated with reduced REM sleep and delta sleep. - Most delta sleep occurs during the first half of the sleep cycle. - Longest REM periods occur during the second half of the sleep cycle. - During REM sleep, high levels of brain and cardiovascular activity occur. - Average time to the first REM period after falling asleep (REM latency) is 90 minutes. - REM periods of 10-40 minutes each occur about every 90 minutes throughout the night. - A person who is deprived of REM sleep one night (e.g., because of inadequate sleep, repeated awakenings, or sedative use) has increased REM sleep the next night (REM rebound). ## Sleep Architecture - Sleep architecture in a typical young adult (Adapted from Wedding D. Behavior & Medicine. St. Louis, MO: Mosby Year Book; 1995:416.) - Awake - REM - Stage 1 (Delta) - Stage 2 (Delta) - Stage 3 (Delta) - Stage 4 (Delta) - REM - Waking - REM - Waking ## Electroencephalographic Tracings and Characteristics of the Awake State and Sleep Stages | Sleep Stage | Associated EEG Pattern (Cycles/Second cps) | % Sleep Time in Young Adults | Characteristics | |---|---|---|---| | Awake | Beta waves (14-30 cps); Alpha waves (8-13 cps) | | Active mental concentration; Relaxed with eyes closed | | Stage 1 | Theta waves (4-7 cps) | 5% | Lightest stage of sleep characterized by peacefulness, slowed pulse and respiration, decreased blood pressure, and episodic body movements | | Stage 2 | Sleep spindle (13-16 cps) and K-complex | 45% | Largest percentage of sleep time; bruxism (tooth grinding) may occur | | Stages 3 and 4 | Delta (slow-wave sleep) waves (1-3 cps)| 25% (decreases with age) | Deepest, most relaxed stage of sleep; sleep disorders, such as night terrors, sleepwalking (somnambulism), and bed-wetting (enuresis), may occur | | Rapid eye movement (REM) sleep | "Sawtooth," beta, alpha, and theta waves | 25% (decreases with age) | Dreaming; penile and clitoral erection; increased pulse, respiration, and blood pressure; absence of skeletal muscle movement | ## Narcolepsy - Patients with narcolepsy have sleep attacks (i.e., fall asleep suddenly during the day) despite having a normal amount of sleep at night. - While typical in amount, their nighttime sleep is characterized by decreased sleep latency, very short REM latency (<10 minutes), less total REM, and interrupted REM (sleep fragmentation). - Decreased REM sleep at night leads to the intrusion of characteristics of REM sleep (e.g., paralysis, nightmares) while the patient is awake resulting in: - Hypnagogic or hypnopompic hallucinations. These are strange perceptual experiences that occur just as the patient falls asleep or wakes up, respectively, and occur in 20%-40% of patients. - Cataplexy. This is a sudden physical collapse caused by the loss of all muscle tone after a strong emotional stimulus (e.g., laughter, fear) and occurs in 30%-70% of patients. - Sleep paralysis. This is the inability to move the body for a few seconds after waking. - Narcolepsy is uncommon. - It occurs most frequently in adolescents and young adults. - There may be a genetic component. - Daytime naps allow the patient to make up some lost REM sleep and, as such, leave the patient feeling refreshed. ## Sleep Disorder Characteristics | Sleep Disorder | Characteristics | |---|---| | Sleep terror disorder | Repetitive experiences of fright in which a person screams in fear during sleep (usually normal in children); The person cannot be awakened; The person has no memory of having a dream; Occurs during delta sleep; Onset in adolescence may indicate temporal lobe epilepsy | | Nightmare disorder | Repetitive, frightening dreams that cause nighttime awakenings; The person usually can recall the nightmare; Occurs during REM sleep | | Sleepwalking disorder | Repetitive walking around during sleep; No memory of the episode on awakening; Begins in childhood (usually 4-8 y of age); Occurs during delta sleep | | Circadian rhythm sleep disorder | Inability to sleep at appropriate times; Delayed sleep phase type involves falling asleep and waking later than wanted; Jet lag type lasts 2-7 d after a change in time zones; Shift work type (e.g., in physician training) can result in work errors | | Nocturnal myoclonus | Repetitive, abrupt muscular contractions in the legs from toes to hips; Causes nighttime awakenings; Treat with benzodiazepine, quinine, or antiparkinsonian, i.e., dopaminergic agent (e.g., levodopa, ropinirole [Requip]) | | Restless legs syndrome | Uncomfortable sensation in the legs necessitating frequent motion; Repetitive limb jerking during sleep; Causes difficulty falling asleep and nighttime awakenings; More common with aging, Parkinson's disease, pregnancy, and kidney disease; Treat with antiparkinsonian agent, iron supplements, or magnesium supplements | | Kleine-Levin syndrome and menstrual-associated syndrome (symptoms only in the premenstruum) | Recurrent periods of excessive sleepiness occurring almost daily for weeks to months; Sleepiness is not relieved by daytime naps; Often accompanied by hyperphagia (overeating); Kleine-Levin syndrome is more common in adolescent males | | Sleep drunkenness | Difficulty awakening fully after adequate sleep; Rare, must be differentiated from substance use or other sleep disorder; Associated with genetic factors | | Bruxism | Tooth grinding during sleep (stage 2); Can lead to tooth damage and jaw pain; Treat with dental appliance worn at night or corrective orthodontia | ## Classification of Sleep Disorders - The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) classifies sleep disorders into sleep-wake disorders, breathing-related sleep disorders, and parasomnias. - Sleep-wake disorders include insomnia, hypersomnolence, and narcolepsy and are characterized by problems in the timing, quality, or amount of sleep. Breathing-related sleep disorders include sleep apnea, as well as circadian rhythm sleep disorder. - Parasomnias are characterized by abnormalities in physiology or in behavior associated with sleep. They include bruxism (tooth grinding) and sleepwalking, as well as sleep terror, REM sleep behavior, and nightmare disorders. - These and other sleep disorders are described in Table 10.3. - Insomnia, breathing-related sleep disorder, and narcolepsy are described below. ## Insomnia - Insomnia is difficulty falling asleep or staying asleep that lasts for at least 1 month and leads to sleepiness during the day or causes problems fulfilling social or occupational obligations. - It is present in at least 30% of the population. ## Summary of Characteristics of Sleep in Typical, Depressed, and Elderly People | Sleep Measure | Typical Young Adult | Depressed Young Adult | Typical Elderly Adult | |---|---|---|---| | Sleep latency | About 10 min | >10 min | >10 min | | REM latency | About 90 min | About 45 min | About 90 min | | Sleep efficiency| About 100% | <100% | <100% | | Percentage delta | About 25% | <25% | <25% | | Percentage REM | About 25% | > 25% | <25% | - Extended REM deprivation or total sleep deprivation may also result in the transient display of psychopathology, usually anxiety or psychotic symptoms. ## Neurotransmitters - Neurotransmitters are involved in the production of sleep. - Increased levels of acetylcholine (ACh) in the reticular formation increase both sleep efficiency and REM sleep. - ACh levels, sleep efficiency, and REM sleep decrease in typical aging as well as in Alzheimer's disease. - Patients taking anticholinergic agents show decreased REM sleep, while patients taking cholinomimetic agents (e.g., physostigmine) show increased REM sleep. - Increased levels of dopamine decrease sleep efficiency. Treatment with antipsychotics, which block dopamine receptors, may improve sleep in patients with psychotic symptoms. - Increased levels of norepinephrine decrease both sleep efficiency and REM sleep. - Increased levels of serotonin increase both sleep efficiency and delta sleep. Damage to the dorsal raphe nuclei, which produce serotonin, decreases both of these measures. Treatment with antidepressants, which increase serotonin availability, can improve sleep efficiency in depressed patients. ## Management of the Major Sleep Disorders | Disorder | Management (in Order of Highest to Lowest Utility) | |---|---| | Insomnia | Avoidance of caffeine, especially before bedtime; Development of a series of behaviors associated with bedtime (i.e., "a sleep ritual"; "sleep hygiene"); Maintaining a fixed sleeping and waking schedule (i.e., "sleep hygiene"); Daily exercise (but not just before sleep); Relaxation techniques; Psychoactive agents (i.e., limited use of sleep agents to establish an effective sleep pattern and antidepressants or antipsychotics, if appropriate) (see Table 16.3)| | Breathing-related sleep disorder (obstructive sleep apnea)| Weight loss (if overweight); Continuous positive airway pressure (CPAP) (a device with a mask applied to the face at night to gently move air into the lungs); Breathing stimulant, e.g., medroxyprogesterone acetate, protriptyline (Vivactil), fluoxetine (Prozac) | | Narcolepsy | Stimulant agents (e.g., modafinil [Provigil]; methylphenidate [Ritalin], if cataplexy is present, sodium oxybate [Xyrem] or an antidepressant may be added); Scheduled daytime naps | ## Management of Sleep Disorders - The management of insomnia, breathing-related sleep disorder, and narcolepsy are described in Table 10.4.