Sleep Disorders Put the Z’s in Disease
What can interfere with sleep? What are sleep disorders?
Any interruption of the normal sleep cycle, a sequential passing from light sleep to deep sleep and which contains both REM and Non-REM components, and which interferes with one’s function during the wakeful hours, is a sleep disorder. Some examples are:
Narcoleptic patients have REM sleep very early in their sleep cycle. This shortens the time it takes to go from wakefulness to deep sleep. This tendency, plaguing a person during the day, can jeopardize their employment and their safety.
Sleep-related breathing disorders
With pulmonary disease, when someone can’t breathe right during the day, they’re not going to be breathing right at night, either. With sleep apnea, however, they may do fine during the day, but at nighttime when they relax, allowing structures such as the soft palate or other obesity-influenced tissues to collapse and obstruct the airway, a person can bounce back and forth along the different phases of sleep, essentially getting very little real rest. Low oxygen is usually accompanied by higher than normal CO2 buildup. This CO2 can become toxic to the brainstem that regulates automatic, unconscious breathing.
Sleep apnea and pulmonary disease
Air hunger, besides resulting in the noisy sputtering and gasping, wakes up people with sleep apnea, sometimes every few moments! How can the brain get anything done?
Obstructive and central sleep apnea are now recognized as having many co-morbidities, such as hypertension, nocturnal cardiac arrhythmias, and fatal heart disease, making it a serious problem.
Obesity hypoventilation, medication-provoked respiratory depression, and hypoventilation due to medical disorders, can all cause a continuous rise in CO2 levels. When this happens, the body loses its ability to prompt reflex breathing, leaving low oxygen as the only remaining trigger. This results in episodic air-hunger alternating with gasping.
REM-related sleep disorders
These can exist either for REM phases or NREM phases.
In REM-related sleep disorders, features of REM sleep invade wakefulness (such as sleep paralysis), nightmares, or lack of paralysis during REM sleep.
These are disorders of arousal (awakening, not sexual), such as recurrent episodes of incomplete awakening, confused arousals, and sleepwalking.
Jet lag, night shifts, or intrinsic circadian dysfunction can prevent jiving with one’s daytime/nighttime rhythm. Such disruptions of the normal sleep cycle can interfere with our human need to synch with the 24-hour day. We evolved to fit into this and anything that interferes with it can prevent “entrainment,” or alignment with the 24-hour day.
Modern people now lead double lives. Unlike our ancestors, we are no longer content to hunt-gather in the daytime for men (or to be involved in childrearing with women), only to collapse for the night at dusk after eating. Today there are movies, candlelight dinners, TV-binging, parties, hobbies, and sexually socializing way into our nights. Additionally, modern cities with their artificial lighting, both inside and outside, have played havoc with our light-dark rheostat—our pineal glands. Therefore, circadian disorders are becoming more common, with an impact not only on our performance, but on our general health, too.
Those who work night shifts have demonstrated, repeatedly, being sleepy at their jobs, impaired cognition (vigilance and error detection), psychomotor disruptions in high-precision tasks and driving, and social dysfunction, such as less ability to regulate emotions. This results in accidents, troubled relationships, and psychological abnormalities like depression and anxiety. Also, heart attacks strokes, and obesity are higher.
How are sleep disorders diagnosed?
The standard for diagnosing sleep disorders is with a sleep study (polysomnogaphy), entailing an observed night’s sleep at a facility that can monitor brainwaves via an EEG, pulse, and respirations. From that, and a careful history, the problems that are causing the ravages of sleep disorders can be identified. This “night out” also allows a before-and-after assessment of approaches to sleep apnea, such as applying a CPAP machine for half the time to compare results with the non-CPAP sleep.
From the EEG readings, which phase of sleep is affected can be identified; from the pulmonary assessment, sleep apnea can be recorded and its severity assessed; and from pulse oximetry, not only hypoxia, but arrhythmias can be spotted.
Sleep disorders are often invisible, but they are insidious. They aren’t noticed because they occur during times of unconsciousness. But the recent troubling association between them and other serious—even life threatening –conditions has prompted an aggressive search for them in the medical office. Of course, one’s bed partner may be all that is needed to know when there is one, but it’s the professional sleep expert who can then identify the particular dysfunction and advise how to treat it, which is covered in the next article.
- American Academy of Sleep Medicine. International Classification of Sleep Disorders, 3rd ed, American Academy of Sleep Medicine, Darien, IL 2014.
- Sateia MJ. International classification of sleep disorders-third edition: highlights and modifications. Chest 2014; 146:1387.
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