Let’s learn about Pathophysiology Sleep Disorders
There are 6 classifications of sleep disorders identified by the American Academy of Sleep
Medicine.
These include insomnia, sleep related breathing disorders, central disorders of hypersomnolence,
circadian rhythm sleep-wake disorders, parasomnias, sleep related movement disorders.
Insomnia is the inability to fall asleep.
Insomnia can be mild, moderate or severe.
Insomnia usually causes tiredness during awake time and can be transient or chronic.
Transient insomnia can be caused by stress or travel across time zones.
It usually only lasts a few days.
Chronic insomnia can have a number of causes including drug abuse, chronic pain, depression,
medications, obesity, the environment and aging.
One of the most common sleep disorders is Obstructive sleep apnea syndrome (OSAS).
Sleep apnea occurs in as much as 24% of men and 9% of women in the United States.
Sleep apnea results from airway collapse causing obstruction of airflow occurring during sleep.
Sleep apnea is associated with apneic periods of 10 seconds or longer, loud snoring, and
gasping for breath.
The breathing abnormalities result in interruption of the sleep cycle.
Sleep apnea can result in hypersomnia or sleepiness during the day.
Sleep apnea can be treated with a continuous positive airway pressure (CPAP) machine
Another disorder that causes hypersomnia is obesity hypoventilation syndrome.
This syndrome may be associated with leptin resistance.
Leptin is a hormone produced by fat cells (adipocytes) that affects satiety or fullness.
In leptin resistance, people don’t feel as full when eating as they should.
Leptin also has an effect on the respiratory system and acts as a stimulant.
Resistance to leptin results in respiratory depression and hypoventilation which results
in an increase in blood CO2 (hypercapnia), which, along with decreased oxygen saturation
causes hypertension, stroke, right-sided congestive heart failure, heart rhythm problems, liver
damage, cyanosis and peripheral edema.
Narcolepsy is characterized by episodes of daytime sleep that can include sleep paralysis,
hallucinations and cataplexy or sudden loss of muscle control.
Narcolepsy Type 1 is characterized by the loss of neurons in the brain that produce
a chemical known as orexin.
Orexin helps to regulate sleep and wakefulness.
Narcolepsy Type 2 is also associated with decreased orexin, but is not as severe as
Type 1.
Narcolepsy can occur from genetics and diseases of the brain.
A common sleep disorder is Circadian rhythm sleep disorder which is characterized by alterations
of the normal sleep wake cycle.
This disorder can be caused by time-zone changes, working hours that require nighttime shifts,
and genetics.
Parasomnias are characterized by abnormal behaviors occurring during sleep.
These include sleepwalking (somnambulism), eating food, violent behavior, and night terrors
and are associated with a loss of REM paralysis.
Restless legs syndrome (RLS)/Willis Ekbom disease is associated with sensations such
as tingling, crawling, and prickling as well as involuntary leg movements that occur during
periods of rest.
RLS is more common in women and the elderly and can occur during pregnancy and with iron
deficiency.
RLS is also associated with fluctuations of dopamine in an area of the brain called the
substantia nigra.
Iron is involved in dopamine production and some patients improve with iron supplements.
I hope you have learned something about sleep disorders and see you next time.