Overview – Sleep-Wake Disorders, Part 2
The various types of Sleep-Wake Disorders in Part 2 are characterized by disturbed sleep involving quality, timing, or duration. There is a bidirectional link between sleep disorders and coexisting psychiatric and/or medical illnesses. Sleep deprivation is a major risk factor for many medical conditions including heart disease, stroke, diabetes, kidney disease, osteoarthritis, common infections like flu and pneumonia, disorders of the musculoskeletal system, and chronic obstructive pulmonary disease. Sleep deprivation is also linked with mental disorders including Parkinson’s Disease, Alzheimer’s Disease, anxiety disorders, and depressive disorders. Sleep disorders are also an established risk factor for the subsequent development of common mental illnesses and may represent the prodromal expression of an episode of mental illness.
Unlike a coma, sleep is a quiet, partially-conscious, and reversible state from which one can be aroused by stimulation—albeit sometimes with difficulty—because sensitivity to environmental stimuli such as sounds, smells, and physical sensations is lowered but not completely blocked. Estimates are that most humans will spend about a third of their life sleeping—important to help them be productive during the remaining two-thirds of their life. Estimates are that 17.0 percent in the general population in the United States have a sleep apnea disorder.
Sleep-Wake Disorders, Part 1, presented information on four types of disorders, one type each day for four days. These were:
- Insomnia Disorder
- Hypersomnia Disorder
- Narcolepsy Disorder
- Circadian Rhythm Sleep Disorder
Sleep-Wake Disorders, Part 2, presents information on six additional types of disorders, Two Related types each for days one and two, and one type each day for days three and four. These are:
Central Sleep Apnea and Obstructive Sleep Apnea hypopnea disorders
Obstructive Sleep Apnea-Hypopnea and Central Sleep Apnea Disorder are both Sleep-Wake Disorders and are quite similar although Obstructive Sleep Apnea-Hypopnea Disorder is the more common. Hypopnea is characterized by overly shallow breathing or an abnormally low respiratory rate. Hypopnea is typically defined by a decreased amount of air movement into the lungs and can cause oxygen levels in the blood to drop. Hypopnea is defined by some to be less severe than Central Sleep Apnea, while other researchers have discovered Hypopnea to have a “similar if not indistinguishable impact” on the negative outcomes of sleep breathing disorders. In sleep clinics, obstructive sleep apnea syndrome or obstructive sleep apnea-hypopnea syndrome—normally is diagnosed based on the frequent presence of apneas and/or hypopneas rather than differentiating between the two phenomena.
Central Sleep Apnea
A significant number of patients with Obstructive Sleep Apnea-Hypopnea Disorder are also diagnosed with Central Sleep Apnea. It is linked with low blood oxygen levels due to the interruption of the normal breathing cycle during sleep, It is a sleep disorder characterized by a brief cessation of breathing during sleep. in which the person briefly stop breathing during sleep. It is caused when the brain temporarily stops sending signals to the muscles that control breathing. A key characteristic of Central Sleep Apnea is where after a long pause, due to gradually increasing levels of carbon dioxide (CO2), shallow breathing is triggered which gradually becomes deeper and deeper. Once carbon dioxide levels reach a safer level, the breathing becomes shallow again.
A diagnosis of Central Sleep Apnea may be given when the patient has more than four central sleep apneas for every hour of sleep, which can be determined using polysomnography. And when the apneas are not caused by some other sleep disorder.
REM Sleep Behavior Disorder & Non-REM (NREM) Sleep Arousal Disorders
REM Sleep Behavior Disorder is a Sleep-Wake Disorder. It is characterized by behaviors in which the patient acts out the dreams through limb movements and talking. It occurs during rapid eye movement or REM sleep, a normal sleep stage that occurs primarily during the second half of the night It accounts for about 20 percent of the sleep cycle and is the usual time for dreaming.
Normally, the human body does not move voluntary muscles during REM sleep except for the eyes, a paralysis phenomenon known as atonia. This is a very good thing as it helps to prevent a sleeping and dreaming individual from acting out their dreams. In REM Sleep Behavior Disorder, however, there is no atonia, no temporary paralysis of arms and legs. This allows movement of voluntary muscles. On waking from these episodes, the individual is not confused or disoriented and is completely alert.
Individuals with REM sleep behavior disorder awaken easily, and report detailed and vivid dream content. They often report “acting out” their dreams. The onset of REM sleep behavior disorder can be gradual or sudden, and episodes may occur occasionally or several times a night. The disorder often worsens with time, and the disorder can last for weeks or months.
Nightmare Disorder or Dream Anxiety Disorder is a Sleep-Wake Disorder that involves recurrent episodes of awakening from sleep. It is characterized by a recollection of terrifying dreams, usually involving fear or anxiety from threats to survival, safety, or physical integrity, but also anger, sadness, or disgust. The content of these scary and disturbing nightmares may vary widely from person-to-person, but common themes include being chased, falling, or feeling lost or trapped.
Nightmares differ from bad dreams in that nightmares cause the individual to wake immediately, usually when the feeling of terror reaches a climax. It can affect the patient’s life in various ways: by disrupting sleep and causing sleep deprivation through a fear of falling asleep, as well as causing or exacerbating other psychological or medical conditions. Nightmare Disorder can have several causes or no identifiable cause, or they can be linked with other disorders.
Approximately one-third of adults with recurrent nightmares have onset of symptoms in childhood. Nightmares occur in all races and cultures, with no reported differences in prevalence. Nightmares tend to decline in school-age and adolescence, presumably due to progressive neurological maturation and reduction in separation anxiety.
Restless Legs Syndrome
Restless Legs Syndrome is a neuro-motor, Sleep-Wake Disorder. It is characterized by unpleasant sensations that usually start at the soles of the feet and move up the calves. It can occur at any time but often tends to worsen in the evening, around bedtime. Individuals with this syndrome try to stop the sensation. They may stamp their feet, shake their legs, stand up, rub their calves, walk back and forth and so it. These activities produce some momentary relief. However, the sensations resume as soon as they stop the movement activities or try to rest. Naturally, this produces a great deal of frustration, which can further disrupt efforts to sleep.
Five diagnostic criteria include:
- While resting, and most frequently and severely at night, there is an urge to move the legs, accompanied by uncomfortable sensations, which are at least partially relieved by movement.
- These symptoms occur at least three times a week for at least three months,
- Resulting in significant distress or impairment in functioning, and
- Symptoms are not better accounted for by another medical or mental disorder, or by the
- Use of prescribed medications or illicit drugs or alcohol
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