Sleep Disorders: An Easy-Reference Guide


There are more than 80 different sleep disorders currently recognized by the International Classification of Sleep Disorders guidebook, and over 20 percent (50-70 million) of Americans suffer from chronic sleep problems at some point in their lives. These disorders can also be symptoms or causes of other health problems, but if left untreated, can lead very quickly to more serious and lifelong conditions. Despite their prevalence, sleep disorders remain poorly identified. Lack of proper diagnosis and treatment contributes not only to increased comorbidity and further health problems, but leads to accidents in the workplace and on the road, great losses in productivity, and further economic costs in the long term. The American Sleep Apnea Association reports that over 60 percent of American adults have never been questioned or evaluated for quality of sleep issues. Meanwhile, nearly 40 percent of Americans report accidentally falling asleep during the day at least once a month. These numbers are on the rise, and next to pain and injury, sleep complaints are at the top of the list of reasons to seek medical attention.

Sleep disorders are classified by the International Classification of Diseases into six major categories: Insomnias, Hypersomnias, Sleep-Related Breathing Disorders, Circadian Rhythm Sleep-Wake Disorders, Parasomnias, and Sleep-Related Movement Disorders. In addition, numerous isolated symptoms are associated with sleep and sleep-related problems. For each of these categories, we will provide some common examples, as well as the symptoms and methods of diagnosis. Remember, this guide is for reference purposes, so please use the links provided for further information and additional resources.


The most common sleep disorder category, insomnias are characterized by sleep difficulties either at sleep onset (“sleep-onset insomnia”), during the night  (“sleep-maintenance insomnia”), or early in the morning. There are diverse causes for these types of disorders, but the inability to attain quality, restorative sleep is common among all sub-categories of insomnias, regardless of the circumstances involved.

In addition to chronic and acute insomnias, a number of insomnias related to comorbidities, drug or medication use, psychological conditions, and combined types involving mixed symptoms are becoming increasingly more prevalent as the issue of daytime sleepiness continues to reach epidemic levels in the U.S. as well as around the world. As these numbers have increased, more attention has been given to the daytime characteristics of the disorder, such as mood or emotional problems, attention difficulties, and impaired performance

Diagnosis and Treatment:

The diagnosis criteria for insomnia disorders has evolved to include the presence of adequate opportunity for sleep, as well as the distinct types of daytime impairments that correspond with routine sleep deprivation. In other words, simply losing sleep would not qualify as an insomnia symptom. One would have to have multiple sleep opportunities in which the failure to sleep adequately is a successive result.

One tool for sleepiness assessment is the Epworth Sleepiness Scale, a widely accepted questionnaire for the subjective evaluation of patients, though further tests may be required to provide an accurate diagnosis. In addition to patient reports and sleep logs, doctors and sleep specialists are able to use neuropsychiatric assessments to evaluate daytime impairments as consequences of chronic or acute sleep deprivation. Data collected in sleep studies can also be used to measure the effects of insomnia on the body. Like most sleep disorders, a range of treatment options may be prescribed based on the specifics of the condition. These can include psychiatric treatments and medications, sleep hormone supplements like melatonin, herbal remedies, exercises, and nocturnal relaxation therapies, as well as more comprehensive lifestyle changes to help prioritize healthy sleep habits in daily life.


The opposite of insomnias, hypersomnias are characterized by excessive sleep, usually in situations that are uncontrollable and unpredictable. This includes narcolepsy (type 1 and type 2), Kleine-Levin syndrome, idiopathic hypersomnia, and hypersomnias due to other conditions (type 3), which are sometimes referred to as secondary hypersomnias. Insufficient sleep syndrome is also categorized as a hypersomnia, though it can be a complex diagnosis due to the voluntary component of its development. Insufficient sleep syndrome, also referred to as chronic sleep deprivation, is the most common cause of daytime sleepiness, but is often under-recognized by patients and the public in general.

Hypersomnia can be primary or secondary. Primary hypersomnias have central origins within the brain and behavior of the patient, while secondary hypersomnias result from other medical conditions. There are many conditions that cause hypersomnia, and more than one type of hypersomnia can develop in a single patient. Diseases, disorders, and other ailments can cause hypersomnias with a variety of frequencies and durations. For example, clinical depression, epilepsy, and multiple sclerosis all cause periods of hypersomnia, as can certain medications or recreational substances. Other sleep disorders like obstructive or central sleep apnea can also cause hypersomnia, especially during the day when sleep deprivation leads to fatigue and exhaustion. In some cases, insomnia can even have corresponding periods of hypersomnia, similar to a bipolar or manic-depressive illness in which volatile shifts in mood, energy, and activity create a critical need for balance and stability. Because so many conditions can cause this disorder, physicians and sleep clinicians must distinguish between hypersomnias and the many disorders that can mimic hypersomnia symptoms. In one example, genetic conditions such as myotonic dystrophy can exhibit sleep onset REM periods, or SOREMPs, which also occur in narcolepsy. Other diseases such as Prader-Willi syndrome, Norrie disease, and Niemann–Pick disease, type C not only mimic hypersomnia symptoms, but can be associated with other secondary disorders that make proper evaluation even more challenging. In such cases, proper diagnosis is crucial for effective treatment of the underlying causes of hypersomnia symptoms.

Diagnosis and Treatment:

The criteria for a hypersomnia diagnosis includes long-term patterns of hypersomnolence, but other factors can be addressed to determine the type and cause of a hypersomnia condition. Diagnosis based on pathophysiology has allowed doctors to test physical changes that occur form the disorder itself. As with insomnia, daytime sleepiness assessments and physical examinations may be employed, but further sleep studies may include use of an electroencephalogram (EEG), in-laboratory polysomnography, in-home sleep testing, multiple sleep latency tests, and portable actigraphy devices to thoroughly assess sleep disorder symptoms and causes. When specific treatments such as prescribed therapies or medications do not completely suppress the daytime sleepiness of patients with hypersomnias, additional causes of the symptoms are often assessed. For example, if a patient with sleep apnea is treated using continuous positive airway pressure (CPAP) therapy, but continues to show high levels of daytime sleepiness, other causes for the symptom will be pursued. Because there is so much crossover in sleep disorder symptoms and causes, these evaluations can be challenging.

Sleep Related Breathing Disorders

Obstructive Sleep Apnea dominates the sleep related breathing disorders as the second most common sleep disorder after insomnia. Sleep related breathing disorders involve difficulty breathing during sleep, and this includes all sleep apnea types (obstructive sleep apnea, central sleep apnea, pediatric or child sleep apnea, and  infant sleep apnea), as well as upper airway resistance syndrome (UARS), and in some cases, obesity hypoventilation syndrome (OHS). Excessive snoring and sleep related groaning can also be included in this category, but tend to be symptoms more than exclusive conditions. More serious and long-term are the chronic illnesses that sleep-disordered breathing contribute to. Research findings suggest that sleep apnea in particular may contribute to mortality in many more cases than are reported by hospitals and coroners, as the routine desaturation of oxygen allows the body to become susceptible to many problems that can worsen over time.

Diagnosis and Treatment:

By far the most common and increasingly popular treatment for sleep-related breathing disorders is the use of PAP therapy devices; primarily CPAP, but in growing numbers, BiPAP (BiLevel CPAP) and APAP (AutoPAP). These devices, while not easy to incorporate into one’s daily sleep routine, show extremely promising results in terms of short-term reduction of symptoms and long-term health benefits. In addition to CPAP, physicians and sleep specialists often prescribe routine exercises and other lifestyle changes meant to induce proper compliance of treatment, but also to improve the overall health and well being of the patient.

Circadian Rhythm Sleep-Wake Disorders

Circadian rhythm sleep-wake disorders involve problems of sleep-wake cycle disruption and imbalance. Conditions such as a delayed and advanced sleep-wake phases which cause late or early sleeping habits, other irregular sleep-wake rhythms, shift work disorders, and jet lag are all characterized by disruptions of the circadian rhythms.

While some argue that these disruptions may be more environmental than physical, the result is the same. The conditions cause sleep to be poor and consistent feelings of fatigue or exhaustion result.

Diagnosis and Treatment:

Circadian rhythm sleep-wake disorders can be diagnosed using sleep studies, but patient accounts or home tests may be sufficient in many cases. Use of mobile sleep apps are very effective in this regard due to their detailed sleep data reports, capturing not only what time a patient sleeps and wakes, but also the levels of sleep experienced throughout the night. Along with subjective data on personal experiences, this use of objective data is ideal for recognizing sleep-wake imbalances. Treatment for these conditions are similar to those for other sleep disruptions, ranging from medication and therapy to lifestyle changes and sleep-centered night and morning routines.


Parasomnias are the most diverse group of sleep disorders recognized by the ICSD. Characterized by unwanted events or experiences during sleep or waking, parasomnias include everything from abnormal and unconscious behaviors to undesirable perceptions, dreams, and hallucinations. Confusional arousals and nightmares, sleepwalking, sleep talking, sleep eating, sleep terrors, sleep paralysis, REM sleep behavior disorder, which involves the acting out of dream scenarios in an unconscious or semi-conscious state, and exploding head syndrome, the waking to loud noises just like an explosion near the head, are all surprisingly common parasomnias. What these experiences have in common is the unwanted behavior or experience interrupting one’s sleep. In the worst cases these interruptions can occur quite frequently to the point that insomnia or insufficient sleep syndrome can occur as a result. In addition to the sleep problems these disorders can cause, the accompanying psychological stress of the experiences themselves can lead to mental and emotional problems that must be treated in addition to the symptoms.

Diagnosis and Treatment:

Because parasomnias are so diverse, their treatments can be just as diverse. Many parasomnias are diagnosed simply from patient accounts and verbal assessments. These disorders often come and go, and the length of the duration can vary greatly. Because of this, medications are often prescribed as needed, to be taken as the symptoms arise, rather than on a regular basis. Other treatments might include relaxation techniques and better sleep hygiene practices, as the disorders are often linked to insufficient sleep, low sleep quality, or changes in sleep routines. Other factors such as stress, depression, recreational drug or alcohol use, and life events can also have an effect on the intensity and duration of parasomnia events.

Sleep Movement Disorders

Sleep movement disorders are just what their label describes: they involve movements during sleep. These disorders can be periodic limb movements, sleep leg cramps, sleep rhythmic movements, restless legs syndrome, bruxism (the grinding of teeth at night), and can even include nocturnal seizures. Sleep movement disorders are very common, especially restless leg syndrome, which becomes more common with age, and like other disorders in this list, can also be a sign of underlying conditions that need to be addressed.

Diagnosis and Treatment:

Sleep movement disorders can be diagnosed using patient accounts, similar to parasomnias, but because they involve obvious physical movements during sleep, can be tested in a sleep clinic or by any physician familiar with the symptoms and characteristics of the various types of sleep movement disorders. These disorders can be easier to identify and diagnose than some of the others on the list, but only if they are frequent occurrences. While the more chronic conditions can be treated with sedatives or anticonvulsant medication, the more acute examples can be very difficult to treat, since the patient has no idea when the movements may transpire.

Research and Progress

In recent years, research has produced a number of promising results for complementary health approaches to sleep disorders, for example, relaxation techniques, meditations, exercises, and other therapies. In one study, mindfulness-based stress reduction, a type of meditation, showed as much success as a prescription drug when tested on patients with insomnia and sleep deprivation. Melatonin has also shown to be extremely effective with jet lag and sleep problems related to shift work. Another study headed by researchers from Aarhus University, has for the first time uncovered the complex brain networks that control sleep as a function of human life and health. have moved to supplant the bedrock model of the sleep cycle with a new epidemiology, focused more on the role of sleep in mental health. Dr. Angus Stevner, one of the lead researchers of the movement, refers to a promising future in the treatment of sleep disorders and mental health in general. “Our results provide a modern description of human sleep as a function of the brain’s complex network activities,” Stevner explains. And he now hopes to identify the integral changes in the brain activity of people suffering from sleep disorders. Despite how commonplace these disorders have become, as Dr. Stevner points out, for the most part they remain a mystery.



American Academy of Sleep Medicine –

American Psychiatric Association –

American Sleep Association –

Eurek Alert –

Hypersomnia Foundation –

National Institutes of Health –

National Sleep Foundation –

NCCIH Clearing House –

Primary Care –

Science Direct – – –

Tuck –