Sleep Disorders

What Are Sleep Disorders?

Sleep disorders are conditions that disturb normal sleep patterns, leading to daytime symptoms and significant impairment in overall health, safety, and quality of life. Changes in one’s sleep patterns can affect the brain, heart, and other organ systems, leading to adverse health effects.

Sleep disorders are highly prevalent. They often go unrecognized or are undiagnosed by patients, healthcare professionals, and the public. Patients may not talk about sleep problems, as they think that it may be normal to have some sleep disorders like insomnia or snoring. They believe it is a part of life, with many patients and healthcare providers not viewing sleep disorders as actual health problems or diseases.

Despite this, according to the Centers for Disease Control and Prevention, over 70 million Americans experience sleep disturbances in one form or another.

What Are the Major Categories of Sleep Disorders?

The third edition of the International Classification of Sleep Disorders (ICSD-3-TR), published by the American Academy of Sleep Medicine, lists seven major categories of sleep disorders:

• Insomnia
• Sleep-related breathing disorders
• Central disorders of hypersomnolence
• Circadian rhythm disorders
• Parasomnias
• Sleep-related movement disorders
• Other sleep disorders

The classification of sleep disorders allows for accurate diagnosis and treatment and improves communication between healthcare providers.

What Are the Types of Sleep Disorders?

The major categories of sleep disorders are described below.

Insomnia

Insomnia refers to sleeping in a way that’s different from how you should or would like to sleep. It is characterized by:

• Difficulty initiating or maintaining sleep
• Daytime sleepiness
• Impairment of daytime activities

Insomnia may occur independently or be comorbid with disorders like anxiety, depression, and other sleep disorders. It is considered chronic if symptoms have been present for more than three months and acute if symptoms have been present for less than three months.

Sleep-Related Breathing Disorders

Sleep-related breathing disorders range from snoring and a mild increase in upper airway resistance to significant upper airway resistance leading to a drop in oxygen levels or complete cessation of breathing, which is called sleep apnea. There are two main types of sleep apnea:

• Obstructive sleep apnea (OSA)
• Central sleep apnea (CSA)

Obstructive sleep apnea occurs when there is complete or nearly complete cessation of airflow accompanied by a preserved respiratory drive, in other words, preserved effort to breathe.

Central sleep apnea results from the instability of controller mechanisms in the central nervous system. A temporary cessation of signaling to the respiratory muscles leads to a complete cessation of breathing. The main difference between obstructive and central sleep apnea is that in central sleep apnea, the respiratory drive stops. A drop in the oxygen level in the blood very commonly accompanies central sleep apnea.

Common sleep apnea symptoms include snoring, excessive daytime sleepiness, fatigue, and sleep fragmentation.

Other types of sleep-disordered breathing include obesity hypoventilation syndrome, in which carbon dioxide levels are chronically elevated in people with a body mass index of greater than 30 due to shallow breathing.

Lastly, congenital central hypoventilation syndrome is a rare genetic disorder caused by a defect in the PHOX2B gene that typically presents with cyanosis (a bluish tint of the skin and mucus membranes) due to reduced oxygen levels during sleep and manifests during early childhood. There are also variants of congenital hypoventilation syndrome, which, in some cases, can present at an older age.

Central Disorders of Hypersomnolence

Central disorders of hypersomnolence, in which a patient experiences excessive sleepiness, include:

• Narcolepsy
• Idiopathic hypersomnia
• Klein-Levin Syndrome
• Insufficient sleep syndrome
• Hypersomnia due to a medical disorder, medication, or psychiatric disorder

Excessive daytime sleepiness is one of the most common complaints of central disorders of hypersomnolence. Other associated symptoms include cataplexy, hallucinations, and sleep paralysis.

• Excessive daytime sleepiness may include falling asleep in class, lecture, meeting, driving, or stopping at a traffic light. Some patients describe this symptom as “being in a fog all day.”
• Cataplexy is described as sudden and transient loss of muscle tone during an emotion, mainly a positive emotion like laughter, but can include negative emotions like anger or sadness. Recovery is usually complete and immediate, and awareness is maintained throughout the episodes.
• Hallucinations can occur while falling asleep or waking up. Common hallucinations are seeing shadows or people in the room, flashes of light, or hearing a voice or sound right before falling asleep or waking up.
• Sleep paralysis, often a frightening experience, is a transient episode that lasts from a few seconds to a few minutes in which a person is unable to perform any voluntary movement. It most often occurs when a person wakes up from sleep.

Circadian Rhythm Sleep-Wake Disorders

Circadian rhythm sleep-wake disorders are disorders in which there is a misalignment between the timing of the sleep-wake cycle and the circadian clock.

Circadian rhythms are 24-hour cycles that are part of the body’s clock to maintain a sleep-wake rhythm. The intrinsic circadian rhythm modulates processes like daily rhythm in core body temperature, melatonin suppression, cortisol, endocrine, immune functions, and metabolism.

If the circadian rhythm gets out of sync, without the right signals from the body’s circadian clock, it may become difficult to fall asleep, stay asleep, or wake up too early.

Delayed Sleep Phase Disorder

This disorder is characterized by difficulty falling asleep and waking up at a desired time and excessive daytime sleepiness.

Advanced Sleep-Wake Phase Disorder

This disorder is characterized by difficulty staying awake in the evening and waking up too early in the morning.

Non-24-Hour Sleep-Wake Rhythm Disorder

This disorder causes a progressive delay in the sleep-wake cycle and circadian rhythm, leading to insomnia and excessive daytime sleepiness. It was first reported in blind individuals but can also be seen in sighted individuals, especially after a head injury.

Irregular Sleep-Wake Rhythm Disorder

In this disorder, patients have a short and irregular sleep cycle with at least three sleep periods across day and night and a lack of a single, consolidated sleep period. This can be seen due to a dysfunction in the internal circadian pacemaker or a reduction in activity, light, or other social cues that influence the circadian rhythms.

Shift-Worker Disorder

This disorder is common in people working in different periods or shifts, for instance, working for a few days in the evening, then at night, and then going back to a day shift, hence called shift-worker disorder. In this disorder, the work period overlaps with the time the circadian rhythm promotes sleep, leading to excessive sleepiness during the work period. However, the body’s circadian alerting signal is high during the allocated sleep period, leading to difficulty falling asleep during that allocated time. This mismatch reduces alertness during the desired waking period, compounded by sleep loss due to circadian-driven insomnia.

Jet Lag Disorder

This is characterized by insomnia or excessive daytime sleepiness associated with trans-meridian jet travel across at least two time zones. It is associated with impaired daytime function, fatigue, and, at times, gastrointestinal upset.

Parasomnias

Parasomnias are unusual behaviors that disrupt sleep, like sleepwalking, sleep talking, sleep terrors, sleep-related eating disorders, sexsomnia, nightmare disorders, and REM behavior disorders^. These behaviors are classified according to the stage of sleep that they occur at, mainly rapid eye movement (REM) and non-rapid eye movement (NREM).

Here are the characteristics of NREM sleep parasomnias:

• Confusional arousals usually occur in children but may occur in 1-4% of the adult population. They are characterized by disoriented behavior limited to the sleeping area and a subsequent impaired recall of events. Sometimes, they are precipitated by other conditions, like sleep apnea.
• Sleepwalking is a combination of ambulation and impaired consciousness. It can also occur in the setting of medications like benzodiazepine receptor antagonists, such as Ambien.
• Sleep terrors are primarily seen in children and are characterized by intense fear. They are started by loud vocalization, increased heart rate, and sweating. Children are usually inconsolable during these episodes.
• Sleep-related sexual behavior is also a type of arousal disorder in which sexual behaviors occur in partial arousal from NREM sleep.
• Sleep-related eating disorders are characterized by recurrent episodes of dysfunctional eating after arousal from sleep. Usually, the food consumed is inedible or toxic substances (e.g., frozen food, cat food, cleaning solutions).

REM parasomnias are characterized by impairment in the suppression of motor activity during REM sleep, leading to dream vocalization and enactment. Dream enactment behavior can vary from small hand movements to violent activities like kicking, punching, or leaping out of bed. It is usually seen in the second half of sleep. People are alert and oriented immediately after awakening. They can remember their dreams, which correlates with the observed behavior.

Other parasomnias include the following:

• Exploding head syndrome is a parasomnia in which a person can experience sudden auditory hallucination, which feels like a loud noise at the initiation of sleep.
• Sleep enuresis is defined by recurrent involuntary urination during sleep. By age six, 90% of children have developed 24-hour control of urination. Sleep enuresis can be either primary in a patient who has never developed nocturnal continence or secondary in a patient who has previously been continent but has subsequently lost bladder control at night. Other sleep disorders like OSA can cause secondary enuresis.
• Nocturnal seizures: The motor behavior of epilepsy can mimic parasomnia, and seizures may occur exclusively during sleep.

Other parasomnias usually bear no specific relationship to the sleep stage.

Sleep-Related Movement Disorders

Sleep-related movement disorders are simple stereotypical movements that disturb sleep; however, patients may or may not be aware of them:

• Restless leg syndrome: This is a disorder in which patients complain of a strong urge to move their limbs, which occurs at rest and predominantly in the evening and night. Patients may describe the symptoms as “ants crawling” or “antsy” sensations in the legs. In severe cases, symptoms may occur in the arm as well. These symptoms may prevent a person from falling asleep or waking up.
• Nocturnal muscle cramps: Nocturnal muscle cramps are sudden and intense involuntary contractions of muscles in the calves or foot that occur during sleep or while in bed. They may be self-limiting but may lead to difficulty falling asleep or waking a person up.
• Sleep-related bruxism: This is characterized by repetitive clenching or teeth grinding, leading to jaw pain and wear down of tooth enamel.
• Rhythmic movement disorder: Rhythmic movement disorders are repetitive movements occurring while falling asleep or during sleep, commonly seen in infants and young children. These may include body rocking, head rolling side to side, or head banging. These movements may be benign but are defined as a disorder if they lead to self-injury or interference with normal sleep.
• Priospinal myoclonus at sleep onset: This is typically a benign condition characterized by sudden myoclonic jerks arising from the chest or abdomen and sometimes the limbs.

A clear description of the events is the key to evaluating all abnormal behaviors and movements during sleep.

What Causes Sleep Disorders?

Behavioral, anatomical, or physiological conditions can cause sleep disorders, including:

• Inadequate sleep hygiene, which is where a person has an irregular sleep time and irregular wake time due to social or work schedules
• Stress and anxiety
• Side effects of medications
• Obesity
• Cardiovascular conditions like atrial fibrillation and heart failure
• Psychiatric conditions like depression and anxiety
• Genetic conditions like congenital central alveolar hypoventilation syndrome

Several causes are listed above, but many times, a specific reason for a sleep disorder is not found.

What Are the Risk Factors for Sleep Disorders?

Risk factors for sleep disorders typically depend on the type of disorder, although there is a significant overlap of these risk factors for all the disorders.

Common risk factors include:

• Older age
• Female sex (especially in insomnia)
• Social isolation
• Stress
• Chronic pain
• Psychiatric disorders
• Medications
• Alcohol and substance use

Obesity, craniofacial, and upper airway abnormalities are more specific risk factors of obstructive sleep apnea, and underlying conditions like heart failure, atrial fibrillation, stroke, and opioid use are seen with central sleep apnea. Certain conditions like restless leg syndrome are seen in pregnancy, iron deficiency, and chronic kidney disease.

What Happens if I Don’t Get Enough Sleep?

When you don’t get enough sleep, your body misses out on the many benefits that good sleep provides. The sleep requirement for an average adult is approximately 7.5-8 hours per night, regardless of environmental differences like temperature, sleeping conditions, noise, etc.

Sleep duration of less than 7 hours is more likely to be associated with poor general health and low overall physical and mental health-related quality of life (HRQOL) than those sleeping greater than 7 hours. Sleeping less than 6 hours is associated with a higher risk of overall cardiovascular disease and hypertension.

How Are Sleep Disorders Diagnosed?

Evaluation of sleep disorders involves a careful and detailed history from a patient, significant other, or family member who may have closely witnessed the signs of sleep disorders, such as snoring or sleepwalking.

A healthcare provider may also order a sleep study, which is a test that records different body systems, including brain waves, muscle tone, breathing pattern, oxygen level, and heart rate during sleep. A sleep study can be done at home, but a more detailed recording of the body systems is sometimes required, and the sleep study is performed at a sleep laboratory facility.

What Questions Will My Healthcare Provider Ask Me During an Exam for Sleep Disorders?

Your healthcare provider may ask about your sleep-wake schedule, nighttime symptoms, daytime activities, and function. They may also ask about your use of caffeine, nicotine, alcohol, and recreational drugs, as these can affect sleep architecture.

It is also helpful for a bed partner to be present during the visit with the sleep provider to provide more information as witnesses to specific symptoms or behaviors of the patient during sleep.

Do I Need to See a Sleep Specialist?

Sleep specialists are neurologists, pulmonologists, or psychiatrists with additional sleep medicine training. While most primary care physicians can manage and treat some sleep disorders, it is recommended that a sleep specialist be seen for more complex sleep disorders.

How Are Sleep Disorders Treated?

Each sleep disorder has a unique treatment. Examples include the following.

• Treatment of insomnia usually involves cognitive behavioral therapy by a sleep psychologist and medications, such as benzodiazepine and non-benzodiazepine receptor antagonists, dual orexin receptor antagonists, or melatonin receptor agonists.
• Treatment of sleep-disordered breathing usually ranges from lifestyle modification to devices like oral appliances, positive pressure or ventilatory devices like CPAP or BIPAP, or implantable devices like hypoglossal or phrenic nerve stimulators.
• Circadian rhythm disorders include careful manipulations of bedtimes, wake times, and other pharmacological and behavioral therapies.

Medications can treat most disorders of excessive sleepiness (hypersomnolence). There are wake-promoting agents like Modafinil and Armodafinil and stimulants like short and long-acting forms of amphetamines.

Similarly, histamine-3 receptor antagonist/inverse antagonist like Pitolisant can be used for hypersomnia and cataplexy symptoms in narcolepsy. In many cases, oxybate salts are also used. All these medications need to be used cautiously due to side effects and addiction potential.

Can Sleep Disorders Be Prevented?

Not all sleep disorders can be prevented. However, disorders like insomnia can be avoided by having a set bedtime and wake time, staying active and exercising during the day, and getting exposed to sunlight or bright light during the day.

Having a wind-down time in the evening, avoiding stimulating agents like nicotine and caffeine in the evening, and avoiding alcohol, which can cause fragmented sleep, can also help. Having a healthy diet and keeping a healthy weight can prevent the occurrence of obstructive sleep apnea.

What Can I Expect if I Have a Sleep Disorder?

Sleep disorders can affect generalized well-being. If you have a sleep disorder, you may have symptoms of early morning fatigue, daytime sleepiness, and irritability. Having a sleep disorder can also affect your mood, personal relationships, and work performance and put you at risk of injury due to drowsy driving or operating heavy machinery.

When Should I See a Healthcare Provider?

You should see a healthcare provider if you experience poor sleep, excessive daytime fatigue, or sleepiness. You should also consider seeing a sleep specialist if you have witnessed snoring, shallow breathing, or any unusual behaviors or movements when you sleep.

Advances in Sleep Medicine

Sleep disorders can adversely impact you psychologically and physiologically. However, with the advances in sleep medicine, these disorders can be diagnosed and treated appropriately. If you think that you may have a sleep disorder, see your healthcare provider to discuss your concerns and treatment options.