NORMAL AWAKE AND SLEEP STATES

I. NORMAL AWAKE AND SLEEP STATES
A. 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.
B. Awake state.
Beta and alpha waves characterize the electroencephalogram (EEG) of the awake individual (Table 10-1).

1. Beta waves over the frontal lobes are commonly seen with active mental concentration.
2. Alpha waves over the occipital and parietal lobes are seen when a person relaxes with closed eyes.
3. Sleep latency (period of time from going to bed to falling asleep) is normally less than 10 minutes.
C. Sleep state.
During sleep, brain waves show distinctive changes (Table 10-1).
1. Sleep is divided into REM (rapid eye movement) sleep and non-REM sleep. Non-REM sleep consists of stages 1, 2, 3, and 4.
2. Mapping the transitions from one stage of sleep to another during the night produces a structure known as sleep architecture (Figure 10-1).


FIGURE 10-1 Sleep architecture in normal young adult
a. Sleep architecture changes with age. The elderly often have poor sleep quality because aging is associated with reduced REM sleep and delta sleep
(stage 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) (Table 10-2).

b. Sedative agents, such as alcohol, barbiturates, and benzodiazepines, also are associated with reduced REM sleep and delta sleep.
c. Most delta sleep occurs during the first half of the sleep cycle.
d. Longest REM periods occur during the second half of the sleep cycle.
3. During REM sleep, high levels of brain activity occur.
a. Average time to the first REM period after falling asleep (REM latency) is 90 minutes.
b. REM periods of 10–40 minutes each occur about every 90 minutes throughout the night.
c. 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).
d. Extended REM deprivation or total sleep deprivation may also result in the transient display of psychopathology, usually anxiety or psychotic symptoms.
D. Neurotransmitters are involved in the production of sleep.
1. Increased levels of acetylcholine (ACh) in the reticular formation increase both sleep efficiency and REM sleep. Acetylcholine levels sleep efficiency,
And REM sleep decrease in normal aging as well as in Alzheimer disease.
2. Increased levels of dopamine decrease sleep efficiency. Treatment with antipsychotics, which block dopamine receptors, may improve sleep in patients
With psychotic symptoms.
3. Increased levels of norepinephrine decrease both sleep efficiency and REM sleep.
4. 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 in depressed patients.
II. CLASSIFICATION OF SLEEP DISORDERS
The Diagnostic and Statistical Manual of Mental Disorders, 4th Edition Text Revision (DSM-IV-TR) classifies sleep disorders into two major categories.
A. Dyssomnias are characterized by problems in the timing, quality, or amount of sleep. They include insomnia, breathing-related sleep disorder (sleep apnea), and narcolepsy, as well as circadian rhythm sleep disorder, nocturnal myoclonus, restless legs syndrome, and the primary hypersomnia s
(e.g., Kleine-Levin syndrome and menstrual-associated syndrome).
B. 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.
C. These sleep disorders are described in Table 10-3.
table 10-3 Other Sleep Disorders and Their Characteristics

Sleep Disorder Characteristics
Sleep terror disorder Repetitive experiences of fright in which a person (usually a child) screams in fear during sleep
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 years 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 days 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
Restless legs syndrome More common in the elderly :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 disease, pregnancy, and kidney disease
Treat with antiparkinson (i.e., dopaminergic) agent (e.g., levodopa, ropinirole [Requip])
Primary hypersomnias
(Kleine-Levin syndrome
and menstrualassociated
syndrome [symptoms
only in the premenstruum]) Recurrent periods of excessive sleepiness occurring almost daily for
at least 1 month
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 abuse or other sleep disorder
Associated with genetic factors
Bruxism Tooth grinding during sleep (stage 2)
Can lead to tooth damage and jaw pain
Treated with dental appliance worn at night or corrective orthodontia
REM sleep behavior
disorder REM sleep without the normal skeletal muscle paralysis
Patients can injure themselves or their sleeping partners
Associated with Parkinson disease; treat with antiparkinson agent

D. Insomnia, breathing-related sleep disorder, and narcolepsy are described below.
III. INSOMNIA
A. Insomnia is difficulty falling asleep or staying asleep that occurs three times per week 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.
B. Psychological causes of insomnia include the mood and anxiety disorders.
1. Major depressive disorder
a. Characteristics of the sleep pattern in depression (Table 10-2)
1. Short sleep latency
2. Repeated nighttime awakenings leading to poor sleep efficiency
3. Waking too early in the morning (terminal insomnia) is the most common sleep characteristic of depressed patients.
b. Characteristics of the sleep stages in depression (Table 10-2).
1. Short REM latency (appearance of REM within about 45 minutes of falling asleep)
2. Increased REM early in the sleep cycle and decreased REM later in the sleep cycle (e.g., in the early morning hours)
3. Long first REM period and increased total REM
4. Reduced delta sleep
2. Bipolar disorder. Manic or hypomanic patients have trouble falling asleep and sleep fewer hours.
3. Anxious patients often have trouble falling asleep.
C. Physical causes of insomnia
1. Use of central nervous system (CNS) stimulants (e.g., caffeine) is the most common cause of insomnia.
2. Withdrawal of agents with sedating action (e.g., alcohol, benzodiazepines) can result in wakefulness.
3. Medical conditions causing pain also result in insomnia, as do endocrine and metabolic disorders.
IV. BREATHING-RELATED SLEEP DISORDER (SLEEP APNEA)
A. Patients with sleep apnea stop breathing for brief intervals. Low oxygen or high carbon dioxide level in the blood repeatedly awakens the patient
during the night, resulting in daytime sleepiness and respiratory acidosis (blood pH < 7.35).
1. In patients with central sleep apnea (more common in the elderly), little or no respiratory effort occurs, resulting in less air reaching the lungs.
2. In patients with obstructive sleep apnea, respiratory effort occurs, but an airway obstruction prevents air from reaching the lungs. Obstructive sleep
apnea occurs most often in people 40–60 years of age, and is more common in men (8:1 male-to-female ratio) and in the obese. Patients often snore.
3. Pickwickian syndrome is a related condition in which airway obstruction results in daytime sleepiness.
B. Sleep apnea occurs in 1%–10% of the population and is related to depression, morning headaches, and pulmonary hypertension. It may also result in sudden death during sleep in the elderly and in infants.
V. NARCOLEPSY
A. Patients with narcolepsy have sleep attacks (i.e., fall asleep suddenly during the day) despite having a normal amount of sleep at night. While normal 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).
B. 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:
1. 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.
2. 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.
3. Sleep paralysis. This is the inability to move the body for a few seconds after waking.
C. Narcolepsy is uncommon.
1. It occurs most frequently in adolescents and young adults.
2. There may be a genetic component.
3. Daytime naps leave the patient feeling refreshed.
VI. TREATMENT OF SLEEP DISORDERS
The treatment of insomnia, breathing-related sleep disorder, and narcolepsy are described in Table 10-4.