Sleep Study Referrals – Disorders

Sleep Disorders occur when an individual has problems with his/her sleep cycle. As a result, it may take patients longer to fall asleep, patients may wake up during the night, wake up early, they may fall asleep throughout the day, have severe nightmares (called night terrors), act out their dreams, or stop breathing during sleep.

The most common types of sleep disorders include delayed sleep phase syndrome (DSPS), insomnia, narcolepsy, night terrors, REM sleep behavior disorder (RBD), and sleep apnea.

There are two phases of sleep: non-rapid eye movement (NREM) sleep and rapid eye movement sleep (REM). The first hour or two of sleep is called NREM sleep. During this phase, the brain waves slow down.

After one to two hours of NREM sleep, the brain activity increases, and REM sleep begins. This is when most dreaming occurs. During REM sleep, the eyes (although closed) move rapidly, breathing becomes irregular, blood pressure rises, and individuals are in a state of temporary sleep paralysis. This temporary immobility prevents individuals from acting out their dreams.

Most sleep disorders can be managed with lifestyle changes and/or medications.

Sleep Apnea

Overview: Sleep apnea is a serious condition that occurs when the individual stops breathing for short periods of time during sleep. Because sleep apnea causes individuals to wake up frequently throughout the night, patients are often drowsy during the day.

Causes: There are two main types of sleep apnea: obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea is the most common form that occurs when the muscles in the throat relax. These muscles support the soft palate, the small piece of tissue that hangs from the soft palate (called the ulva), the tonsils, and the tongue. When these muscles relax, the patient is unable to breathe.

The brain senses this inability to breathe and causes the individual to wake up and start breathing again. This process may occur 20 to 30 times or more each hour during sleep. Most patients do not even realize this happens.

Obstructive sleep apnea occurs most often in older adults. It is also twice as likely to occur in men as women. Obese individuals have an increased risk of experiencing obstructive sleep apnea because they have excess fat in their upper airways.

Central sleep apnea occurs when the brain does not send proper signals to the muscles that control breathing during sleep. This is usually caused by heart disease. They are more likely to remember waking up in the middle of sleep than patients with obstructive sleep apnea.

It is possible to have a combination of both types of sleep apnea, which is called complex sleep apnea. Central sleep apnea may develop at any age, and it affects males and females equally. Some evidence suggests that 15% of patients with sleep apnea have complex sleep apnea.

Symptoms: Many of the symptoms of obstructive sleep apnea and central sleep apnea are the same. Common symptoms of both of these disorders include loud snoring, waking from sleep abruptly, difficulty staying asleep, waking up with a dry mouth or sore throat, and drowsiness during the day. In addition, individuals with central sleep apnea often wake up with shortness of breath and headaches.

Patients with central sleep apnea may also experience shortness of breath and headaches when they wake up from sleep.

Diagnosis: If sleep apnea is suspected, the patient may be asked to spend a night at a sleep center. At a sleep center, the patient’s sleep patterns will be observed and analyzed. Several tests, including a nocturnal polysomnography, oximetry, and portable cardiorespiratory test, may be performed to monitor the patient’s conditions.

During a nocturnal polysomnography test, a specialist will monitor the electrical activity of the brain and heart, the movement of the muscles, the movements of the eyes, and breathing patterns of the patient during sleep.

During an oximetry test, a small machine monitors and records the oxygen level of the patient during sleep. A small sleeve is placed over one of the fingers. This test may be performed at a sleep center or at home. Patients with sleep apnea will have low levels of oxygen before each awakening.A healthcare provider may give the patient a portable cardiorespiratory test to perform at home. These tests involve oximetry, measurement of breathing patterns, and the measurement of airflow.

REM Sleep Behavior Disorder

Overview: REM sleep behavior disorder (RBD) occurs when patients do not experience temporary paralysis during REM sleep. As a result, patients act out their dreams, which are often intense, vivid, and violent. The patient may yell, punch, kick, jump up from bed, and punch the air.RBD typically occurs in middle-aged to elderly patients. It is more common in men than women.

Causes: The exact cause of RBD remains unknown. However, the disorder has been linked to many degenerative neurological (brain) disorders, including Parkinson’s disease. It is important to note that not all patients with RBD develop neurological disorders.

Symptoms of RBD may also occur during withdrawal from alcohol or sedative-hypnotic drugs. However, this form is only temporary and goes away once the person has gone through withdrawal.

Symptoms: Patients with RBD act out their dreams. This may include yelling, screaming, thrashing around, kicking, punching, sitting up in bed, or getting out of bed during sleep. In some cases, RBD may cause self injury or injury to the bed partner. If the person wakes up in the middle of an attack, he/she is often able to remember the dream in detail.

Night Terrors

Overview: Night terrors are similar to nightmares. However, night terrors are scarier and more intense. Night terrors typically cause individuals to scream and thrash about during sleep. Individuals usually do not remember their night terrors when they wake in the morning.Night terrors primarily affect young children, usually between the ages of four and 12. Night terrors during childhood are not usually a cause for concern, and most children outgrow night terrors by adolescence.

In rare cases, adults may experience night terrors, usually in response to extreme stress or anxiety. Adults may benefit from medications if they experience frequent night terrors.

Causes: Many factors, including fatigue, stress, illnesses (especially those that cause fevers) and medications that affect the brain or spinal cord (such as stimulants), may cause night terrors.

Symptoms: Night terrors typically occur two to three hours after an individual has fallen asleep. During sleep, the patient may scream or yell, sit up in bed, thrash around, sweat, or breathe rapidly. If a parent or bedmate tries to hold or comfort the patient during a night terror, the patient may unknowingly put up a fight. Adults, who are larger and stronger than children, may even injure their bedmate as they thrash around during night terrors. Most night terrors only last a few minutes. Once the individual wakes up, he/she probably will not remember the episode.


Overview: Narcolepsy is a sleep disorder that occurs when individuals are overwhelmingly tired and spontaneously fall asleep throughout the day. Patients have a hard time staying away for extended periods of time, regardless of the circumstances or how much sleep they get.The severity of narcolepsy varies among patients. Most patients are diagnosed between the ages of 10 and 25. It is uncommon for patients to be diagnosed with the disorder when they are older than 40 years of age.

Causes: Researchers are still performing studies to fully understand the causes of narcolepsy. Scientists believe that genetics may play a role in the disorder. However, since only about two percent of narcoleptic patients have family histories of the disorder, other factors besides genetics are probably involved.Narcoleptic patients may have imbalances in the brain chemicals that help control sleep. For instance, one chemical called hypocretin has been shown to help individuals wake from sleep and stay awake. Patients with narcolepsy typically have low levels of this chemical. However, researchers do not know what causes individuals to have low levels of hypocretin. It has been suggested that the body’s immune system might attack hypocretin-producing cells by mistake.

Symptoms: Patients with narcolepsy are excessively tired throughout the day. Individuals can fall asleep at any time or any place throughout the day. For instance, they may fall asleep in the middle of conversations with friends. These sleep attacks may last anywhere from a few minutes to a half hour. Individuals also experience decreased alertness and concentration.

About 70% of narcoleptic patients also experience periodic episodes of cataplexy, which is a sudden and temporary loss of muscle tone. This condition, which may last anywhere from a few seconds to a few minutes, may cause symptoms that range from slurred speech and drooling to complete muscle weakness. Laughter or strong emotions, especially excitement and sometimes fear or anger, typically trigger cataplexy. Some patients may only experience cataplexy a few times a year, while others may experience symptoms several times a day.

Sleep paralysis may also occur while the individual is falling asleep or awakening. This temporary inability to move typically lasts anywhere from a few seconds to several minutes. When sleep paralysis occurs, patients may feel scared because they are often aware of what is happening even though they cannot move.

Some patients may experience hallucinations. This occurs if the patient is semi-awake when he/she starts dreaming.Additional symptoms may include restless nighttime sleep or sleepwalking. Some patients may also act out their dreams and talk or move their arms or legs.


Overview: Insomnia occurs when individuals have difficulty falling or staying asleep, and they wake up too early in the morning. It is a common health problem that can cause excessive daytime sleepiness and a lack of energy. Long-term insomnia may cause an individual to feel tired, depressed, or irritable. Individuals may also have trouble paying attention, learning, and remembering, which may prevent them from performing fully on the job or at school. Severe insomnia can result in neurochemical (brain chemical) changes that may lead to problems, such as depression and anxiety, further complicating the insomnia.Causes: There are many potential causes of insomnia. Psychological disorders, such as stress, anxiety, depression, and bipolar disorder, may lead to insomnia. Certain health conditions, including arthritis, overactive thyroid glands, gastrointestinal disorders (such as diarrhea or ulcers), Alzheimer’s disease, Parkinson’s disease, sleep apnea (discussed in detail below), and restless legs syndrome (RLS), may cause insomnia. Other factors, such as taking certain medications (such as stimulants, nasal decongestants, and some antidepressants), consuming caffeine, jet lag, wake-sleep pattern disturbances, excessive sleep during the day, and excessive physical or intellectual stimulation before bed, may cause insomnia.Symptoms: The main signs and symptoms of insomnia are trouble falling or staying asleep or waking early, followed by a distinct feeling of fatigue (tiredness) the following day. Most often, daytime symptoms will bring people to seek medical attention. Daytime problems caused by insomnia include anxiousness, irritability, fatigue, poor concentration and difficulty focusing, impaired memory, decreased motor coordination, irritability, impaired social interaction, and motor vehicle accidents because of fatigued, sleep-deprived drivers.

Delayed Sleep Phase Syndrome (DSPS), also called circadian rhythm sleep disorder- delayed sleep phase type, occurs when a person’s internal clock is not in sync with the normal sleep patterns of most adults. The patient’s sleep pattern is delayed by two or more hours, causing later bedtimes and wake times.

When patients follow their internal clocks and go to bed when they are tired, they get enough sleep. However, patients with DSPS have abnormal internal clocks, and they typically do not feel tired until 2:00 a.m. or later. Since this does not match normal school and work schedules, patients feel tired when they try to follow conventional sleeping schedules.

DSPS patients typically find that sleeping aids do not help them fall asleep any earlier.

DSPS is a long-term condition that is most common among adolescents. DSPS can develop suddenly or gradually. Symptoms generally go away spontaneously without treatment.

Causes: DSPS is not caused by jet lag, working late shifts, working irregular shifts, or other external factors. Instead, DSPS is caused by an abnormality in the patient’s internal clock (called the circadian rhythm).

Symptoms: Patients with DSPS generally have difficulty falling asleep before 2:00 a.m. Individuals often feel tired upon waking. Individuals may continue to feel fatigued or drowsy throughout the day.