Sleep Disorders​

Sleep is a reversible phase of diminished responsiveness, motor activity, and metabolism. This process is a complex and dynamic phenomenon, occurring in 4–5 cycles a night, and generally divided into non–rapid eye movement (NREM) sleep and REM sleep stages. NREM sleep, consisting of 3 stages, represents the period of transition from wakefulness, somnolence, and then deep sleep. REM sleep is characterized by rapid irregular eye movement, but with voluntary muscle atonia. The sleep stages and associated disorders are studied through the use of polysomnography, a multimodal test evaluating the brain waves, along with ocular and motor activities. Sleep disorders can be primary (which do not stem from any health problem) or can be attributable to underlying conditions or medications.

Circadian rhythm sleep–wake disorders are a group of conditions marked by recurrent patterns of sleep disruption. These disorders can be due to an alteration of the circadian system (intrinsic) or a misalignment between an individual’s inner circadian rhythm and the environment (extrinsic). The disruption impairs the individual’s daily activities. There are 6 different subtypes, including delayed and advanced sleep–wake phase disorder, irregular and non-24-hour sleep–wake rhythm disorder, shift-work disorder, and jet lag. Diagnosis is generally clinical, but using tools such a sleep diary and actigraphy help in determining the disorder. Management for circadian rhythm sleep–wake disorders involves light therapy, behavioral modification, and pharmacotherapy, such as with melatonin.

Parasomnias are a pattern of sleep disorders marked by unusual actions, activities, or physiological events that occur during sleep or sleep-wake transitions. Parasomnias are divided into which sleep phase the symptoms occur, either rapid eye movement (REM) or non-REM (NREM). Symptoms may include simple or complex abnormal movements, such as sleep talking, sleepwalking, sleep terrors, and dream enactment, or emotions, dreams, and autonomic activity. Diagnosis involves a thorough history taking from the patient and the partner. In some cases, polysomnography is required, especially if comorbid sleep disorders are suspected. Some conditions resolve over time without any treatment. For those that require intervention, options include lifestyle or risk modifications, different forms of therapy, and medications. Choice of management is affected by patient preferences.

Insomnia is a sleep disorder characterized by difficulty in the initiation, maintenance, and consolidation of sleep, leading to impairment of function. Patients may exhibit symptoms such as difficulty falling asleep, disrupted sleep, trouble going back to sleep, early awakenings, and feeling tired upon waking. The disorder can be acute (< 3 months), which can progress to the chronic form (≥ 3 months). Multiple risk factors contribute to having insomnia, including medical illnesses, psychiatric disorders, medications, and the sleep environment. Diagnosis starts with a detailed history and sleep diagnostic aids (sleep diary, sleep problems questionnaire). The 1st line of management is nonpharmacologic, i.e., identifying the stressor(s), implementing sleep hygiene, and utilizing cognitive behavioral therapy. Medications are used with nonpharmacologic intervention or after initial management has failed.

Narcolepsy is a neurological sleep disorder marked by daytime sleepiness and associated with cataplexy, hypnagogic hallucinations, and sleep paralysis. There are 2 types of narcolepsy: type 1 is associated with cataplexy and type 2 has no association with cataplexy. A decreased level of orexin is noted in patients with type 1 narcolepsy. Diagnostic criteria are made using sleep studies that show a decrease in REM latency. Management includes good sleep hygiene. Medications that act as CNS stimulants and antidepressants are used to target the cataplexy. Narcolepsy is a life-long disorder with no definitive cure.