History

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.[9]

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. 

Physical Examination

Signs of sleep disorders are as follows:

• Poor concentration
• Drowsiness
• Slowed reaction time
• Hypertension (which can be caused by sleep apnea)
• Poor growth, enlarged tonsils, and narrowed airway (findings of OSA)

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:

• Hemoglobin and hematocrit
• Arterial blood gases (ABG) 
• Thyroid function tests
• Drug and alcohol toxicity screening 
• Iron studies
• CRP (increased in patients with OSA).[10]

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.[11]

Treatments for sleep disorders depend on the type of sleep disorder. Treatment of insomnia can be broadly categorized into non-pharmacological and pharmacological treatments.

Non-pharmacological treatments:

• Cognitive-behavioral therapy (CBT): these are psychological and behavioral techniques that can be helpful for treating insomnia. Depending on the specific symptoms, some of the techniques employed in CBT are:
• Sleep restriction therapy (SRT): SRT limits the total time allowed in bed so that the drive to sleep increases.
• Stimulus control therapy: it helps in changing sleep habits so that the patients don't have difficulty falling asleep. Patients should not go to bed until they are sleepy. Also, the bed should be used only for sleeping and not for watching television or reading books.
• Relaxation training: Relaxation techniques may be implemented before sleep. Meditation and breathing exercises are some of the relaxation techniques. It begins with being in a comfortable position and closing eyes. The mind and thoughts should be redirected towards a peaceful image, and relaxation should be allowed to spread throughout the body.
• Hypnosis: the hypnotherapist uses different therapeutic techniques like verbal repetition and mental images, which makes the patient feel calm and relaxed, promoting restful sleep.
• Sleep hygiene : (see: patient education section)

Pharmacologic therapy:

• Histamine type 1 receptor blockers: due to their sedative effects, these drugs can be helpful in patients with sleep disorders. However, due to their anticholinergic effect, these drugs should be avoided in the elderly. Examples include chlorpheniramine and diphenhydramine.
• Benzodiazepines (BZD): these drugs are the mainstay in the treatment of insomnia. The drugs bind to a special benzodiazepine site on the gamma-aminobutyric acid (GABA) receptor complex, enhancing the activity of neurotransmitters. These drugs suppress the REM sleep, reduces stages 3 & 4 sleep while increasing stage 2 sleep. Examples include flurazepam and temazepam.
• Non-benzodiazepine hypnotics: these agents are used for the treatment of acute and short term insomnia. These drugs have non-BZD like chemical structures but interact with the GABA-BZD receptor, causing sedation. Examples include zolpidem and zaleplon.
• Melatonin receptor agonists: the melatonin receptors MT1 and MT2 are implicated in regulating sleepiness and the sleep-wake cycle. Melatonin receptor agonists act on these receptors and hence improve sleep through the endogenous regulating system. These drugs are used in circadian rhythm sleep disorders, jet lag, delayed sleep-wake phase disorder (insomnia with difficulty in sleep onset).[12] [13][14]Example includes ramelteon. 
• Orexin receptor antagonists: orexin promotes wakefulness. Thus, antagonism of this receptor helps in sleep. An example includes suvorexant.

Other interventions:

• Sleep apnea can be alleviated by losing weight, the use of continuous positive airway pressure (CPAP), and, sometimes, surgical treatment. The drug solriamfetol, selective dopamine, and norepinephrine reuptake inhibitor can be used to increase wakefulness in patients with OSA who have excessive sleepiness.[15]
• A number of medications can be used for the treatment of narcolepsy. Modafinil, a non-amphetamine stimulant that promotes wakefulness, is considered as first-line therapy for narcolepsy as it reduces daytime sleepiness, is well tolerated, and has less abuse potential compared to traditional stimulants (amphetamines, methylphenidate). These traditional drugs are second-line drugs. Patients with significant cataplexy may benefit from REM suppressing drugs such as anti-depressants and sodium oxybate.
• Light-phase shift therapy is useful for sleep disturbances associated with circadian rhythm abnormalities.[16] Patients may be exposed to bright light to help normalize the sleep schedule.
• Gabapentin enacarbil significantly improves restless leg syndrome and hence alleviates sleep disturbance.[17]

The differential diagnosis of sleep disorder are as follows:

• Post-traumatic stress disorder (PTSD)
• Depression
• Anxiety disorder
• Bipolar disorder
• Opioid abuse
• Alcoholism
• Stimulants abuse (amphetamine)
• Chronic obstructive pulmonary disease (COPD)
• Hyperthyroidism

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.[18]

The patients with periodic limb movement disorder of sleep have a higher risk of cerebrovascular accidents.[19]

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.[20]

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:

• maintain a regular schedule i.e, go to bed and wake up at the same time every day
• use the bed for sleep and sex only. Avoid watching television, looking at phones or reading in the bed
• exercise almost every day, but not right before bedtime
• avoid caffeine or smoking mostly during the evening
• maintain a dark, cool, and quiet environment in the bedroom
• avoid struggling to fall asleep in bed. If you can't sleep, get up and try again later or change the bed

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.