Sleep is a complex biological process. It is a reversible state of unconsciousness in which there are reduced metabolism and motor activity. There are two different kinds of sleep: rapid eye movement (REM) sleep and non-REM (NREM) sleep. Most young adults first enter NREM sleep from the drowsy state. NREM sleep (dreamless sleep) is further divided into four stages (1-4). The first stage N1, is the lightest stage, characterized by a transition from wakefulness to sleep. Then, the second stage N2 follows, which comprises the largest percentage of total sleep. Benzodiazepines work by increasing stage N2 sleep. Then, the adult enters into deep stages of sleep N3 and N4. After about 70 to 80 minutes of a deep sleep, sleep lightens, and a REM period follows, which is usually associated with active dreaming and bodily movements. This cycle is repeated at intervals of about 90 minutes. Towards morning, there is less stage 3 & 4 sleep and more REM sleep.
Sleep disorders are a group of conditions that disturb the normal sleep patterns of a person. Sleep disorders are one of the most common clinical problems encountered. Inadequate or non-restorative sleep can interfere with normal physical, mental, social, and emotional functioning. Sleep disorders can affect overall health, safety, and quality of life. There is a study showing significant impairment in quality of life in patients with insomnia.
There are many different types of sleep disorders. They can be broadly categorized into primary and secondary. Primary sleep disorders result from endogenous disturbances, whereas secondary sleep disorders are the result of various medical and psychiatric conditions such as depression, thyroid problems, and stroke.
Primary sleep disorders can be further divided into parasomnias and dyssomnias:
Sleep disorders are common in both adults and children. However, children with sleep disorders may present with different symptoms than adults. Children with sleep problems may exhibit motor overactivity, inattentiveness, irritability, or oppositional behavior rather than overt sleepiness.
There are different causes for different sleep disorders. Sometimes the cause is unknown. The major causes may be broadly divided into medical conditions, psychological conditions, and other factors.
Other factors causing sleep problems:
Parasomnias such as sleepwalking, confusional arousals, sleep terrors, sleep talking, and nightmares are very common during childhood. Obstructive sleep apnea occurs in about 1% to 5% of children. As people age, the incidence of sleep problems also rise. Approximately 50% of older adults have sleep problems.
Other comorbid conditions of old age, such as diabetes, hypertension, dementia, and anxiety, are all associated with sleep disturbances. Restless leg syndrome and periodic limb movement disorder are also more prevalent in the elderly. Primary insomnia is more common in women over age 50 than their male counterparts.
The symptoms of sleep disorders depend on the specific disorder.
Insomnia may present as difficulty falling asleep and/or staying asleep. Patients report taking thirty minutes or more to fall asleep (for those with sleep initiation difficulties) or spending thirty minutes or more awake during the night (for those with sleep maintenance difficulties). The diagnosis of insomnia also requires the presence of compromised daytime function, which includes one or more symptoms like fatigue, daytime sleepiness, poor attention, increased accidents, aggression, reduced motivation, or energy. Insomnia can often be a persistent or recurrent condition with exacerbations connected to medical, psychiatric, and psychosocial stressors.
Hypersomnia is generally seen in adolescents or young adults. The patients with hypersomnia complain of disabling excessive day time sleepiness. They find it difficult to maintain alertness during the major waking hours of the day with sleep occurring unintentionally or at inappropriate times that interferes with the daily routine.
Narcolepsy is a chronic neurological disorder caused due to the brain's inability to control sleep and wakefulness. It is associated with a low cerebrospinal fluid level of orexin-A/hypocretin-1. Patients with narcolepsy complain of excessive chronic daytime sleepiness with varying amount of cataplexy (transient loss of muscle tone in response to intense emotion such as laughter), hallucinations while falling asleep (hypnagogic hallucinations) or hallucinations while waking (hypnopompic hallucinations), and sleep paralysis (inability to move immediately after awakening).
Obstructive sleep apnea (OSA) is a disorder characterized by obstructive apneas/hypopneas caused due to the laxity of pharyngeal musculature leading to the repetitive collapse of the upper airway during sleep. The patients with OSA complain of excessive daytime sleepiness, morning headaches, poor judgment, impotence, and depression. Loud snoring, gasping, choking, snorting, or interruptions in breathing while sleeping is often reported by their bed partners. OSA is a very common comorbidity in a patient with bipolar disorder. Higher BMI and residual depressive symptoms are the two best independent predictors of OSA in a patient with bipolar disorder.
Advanced sleep phase syndrome is a circadian rhythm disorder characterized by an inability to stay awake in the evening (usually after 7 pm). These patients complain of early morning insomnia due to their early bedtime.
Delayed sleep phase syndrome is also a circadian rhythm disorder in which the affected individuals generally go to bed and usually arise two or more hours late than the desired time. These patients often complain of sleep-onset insomnia and excessive morning sleepiness.
REM sleep behavior disorder is a parasomnia characterized by dream-enactment behaviors that emerge during a loss of REM sleep atonia. The patients with REM sleep behavior disorder show movements such as kicking, punching, arm-flailing, or jumping from bed in response to violent dreams. Patients are generally brought to medical attention due to potentially injurious actions to themselves or their bed partners. The patient can recall the dream if he awakens during the episode. This disorder may be associated with other medical conditions such as Parkinson's disease, Lewy body dementia, or multiple system atrophy.
Night terrors are most common in children aged 2 to 12 years of age, which usually resolve spontaneously as child ages. It occurs in non-REM sleep. Parents usually complain of their child exhibiting features like screaming, intense fear, and flailing while still asleep during an episode of the night terror. There is no memory of the event.
Nightmare is a parasomnia that occurs during REM sleep, usually in the middle of the night and early morning. During a nightmare, the person may scream and yell out things. The difference of nightmare with a night terror is that the person can become fully alert when awakened during a nightmare. Also, there is a memory of the event in a nightmare i.e., and a person can recall a nightmare.
Restless leg syndrome is a sleep movement disorder in which the patients have an uncomfortable sensation and an urge to move the legs while trying to fall asleep. The symptoms are relieved by walking or moving the legs.
Signs of sleep disorders are as follows:
A variety of information is required to evaluate sleep problems. After a detailed medical history, medication history, and physical examination; some of the investigations appropriate to diagnose sleep disorders are as follows:
Sleep diary: The sleep diary, or sleep log, is a subjective paper record of sleep and wakefulness over a period of weeks to a month. Patients should record the detailed description of sleep, such as bedtime, duration until sleep onset, the number of awakenings, duration of awakenings, and nap times.
Sleep studies: Objective measures of sleep may be obtained by sleep studies such as electroencephalography (EEG) or polysomnography (PSG). PSG is largely regarded as the gold standard for the diagnosis of OSA and other sleep disorders. During PSG, numerous monitoring devices are connected to the patient, and the patient is allowed to sleep. Various physiologic parameters such as respiratory effort, sleep stages, electrocardiography, airflow, body position, and limb movements are assessed. The information obtained from these parameters helps to diagnose various REM & NREM sleep disorders as well as determine the causes of sleep disturbance.
Laboratory studies: Some of the lab studies appropriate for those with sleep disorders include:
Overnight oximetry: This involves the use of a probe that is worn on the finger or earlobe, which continuously measures oxygen levels and heart rate. It identifies the individuals who are at risk for nocturnal breathing disorders such as sleep apnea.
Actigraphy: In this test, a device called the actigraph is worn on the wrist like a watch. The signals are detected when there is movement. Very few to no signals are recorded during sleep/inactivity. This device can be used to assess sleep-wake cycles or circadian rhythm over an extended period of time and thus can be used to diagnose advanced or delayed sleep phase syndrome.
Multiple sleep latency testing (MSLT): This is an objective test which determines the degree of sleepiness. This test is often called a nap study. On the day following an overnight PSG study, the patient is asked to take four or five naps over a period of 8-10 hours. Each nap lasts about 20 minutes. These tests are useful in identifying excessive daytime sleepiness, which can be present in various disorders such as sleep apnea, hypersomnia, and narcolepsy.
Indices and scoring systems: If there is a suspicion of depression causing insomnia, Beck Depression Inventory can be used. Similarly, tools like a structured clinical interview for sleep disorders (SCISD) is a brief, reliable interview assessment tool for sleep disorders.
Treatments for sleep disorders depend on the type of sleep disorder. Treatment of insomnia can be broadly categorized into non-pharmacological and pharmacological treatments.
The differential diagnosis of sleep disorder are as follows:
Insufficient sleep can result in industrial or motor vehicle accidents, decreased work performance, and cognitive dysfunction. The prognosis of sleep disorders depends widely on the cause of the sleep disorder. Insomnia due to OSA generally resolves with the treatment, whereas the patients with chronic insomnia have increased risk of depression, anxiety, and reduced quality of life.
Untreated sleep disorders may lead to the development of various serious complications. Mood and anxiety disorders may develop. Sleep deprivation can lead to the formation of false memory and a decline in cognitive functioning.
The patients with periodic limb movement disorder of sleep have a higher risk of cerebrovascular accidents.
Obstructive sleep apnea, apart from the loss of sleep, can damage the brain, and affect the cardiovascular system. Obstructive sleep apnea can also reduce the thickness of the retinal nerve fiber layer.
All patients should be educated well and encouraged to practice good sleep hygiene. "Sleep hygiene" is a term used to describe good sleep habits.
The following advice should be given to the patients to practice good sleep hygiene:
Also, if the patient is taking sedative-hypnotic medications, it should be clearly documented in the medical record. Patients should be counseled to avoid driving and operating machines when under these medications.
The proper management of sleep disorders requires the efforts of an interpersonal healthcare team. Consultation can help evaluate patients for medical and psychiatric causes of insomnia. The management team includes a psychiatrist, neurologist, pulmonologist, sleep medicine specialist, and dietitian. Surgical consultations are required for some of the underlying causes of insomnia, such as in cases of OSA, which may require palate surgery. Interdisciplinary collaboration is important for good patient outcomes in sleep disorders.
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