Polysomnography in the context of "Electrocardiography"

A sleep disorder, or somnipathy, is a medical disorder that disrupts an individual's sleep patterns and quality. This can cause serious health issues and affect physical, mental, and emotional well-being. Polysomnography and actigraphy are tests commonly ordered for diagnosing sleep disorders.

Sleep disorders are broadly classified into dyssomnias, parasomnias, circadian rhythm sleep disorders, and other disorders (including those caused by medical or psychological conditions). When a person struggles to fall or stay asleep without an obvious cause, it is referred to as insomnia, which is the most common sleep disorder. Other sleep disorders include sleep apnea, narcolepsy, hypersomnia (excessive sleepiness at inappropriate times), sleeping sickness (disruption of the sleep cycle due to infection), sleepwalking, and night terrors.

Dementia with Lewy bodies (DLB) is a type of dementia characterized by changes in sleep, behavior, cognition, movement, and regulation of automatic bodily functions. Unlike some other dementias, memory loss may not be an early symptom. The disease worsens over time and is usually diagnosed when cognitive impairment interferes with normal daily functioning. Together with Parkinson's disease dementia, DLB is one of the two Lewy body dementias. It is a common form of dementia, but the prevalence is not known accurately and many diagnoses are missed. The disease was first described on autopsy by Kenji Kosaka in 1976, and he named the condition several years later.

REM sleep behavior disorder (RBD)—in which people lose the muscle paralysis (atonia) that normally occurs during REM sleep and act out their dreams—is a core feature. RBD may appear years or decades before other symptoms. Other core features are visual hallucinations, marked fluctuations in attention or alertness, and parkinsonism (slowness of movement, trouble walking, or rigidity). A presumptive diagnosis can be made if several disease features or biomarkers are present; the diagnostic workup may include blood tests, neuropsychological tests, imaging, and sleep studies. A definitive diagnosis usually requires an autopsy.

A hypnogram is a form of polysomnography; it is a graph that represents the stages of sleep as a function of time. It was developed as an easy way to present the recordings of the brain wave activity from an electroencephalogram (EEG) during a period of sleep. It allows the different stages of sleep: rapid eye movement sleep (REM) and non-rapid eye movement sleep (NREM) to be identified during the sleep cycle. NREM sleep can be further classified into NREM stage 1, 2 and 3. The previously considered 4th stage of NREM sleep has been included within stage 3; this stage is also called slow wave sleep (SWS) and is the deepest stage of sleep.