Concept
Sleep
Related concepts (38)
Activation-synthesis hypothesis
The activation-synthesis hypothesis, proposed by Harvard University psychiatrists John Allan Hobson and Robert McCarley, is a neurobiological theory of dreams first published in the American Journal of Psychiatry in December 1977. The differences in neuronal activity of the brainstem during waking and REM sleep were observed, and the hypothesis proposes that dreams result from brain activation during REM sleep. Since then, the hypothesis has undergone an evolution as technology and experimental equipment has become more precise.
Cataplexy
Cataplexy is a sudden and transient episode of muscle weakness accompanied by full conscious awareness, typically triggered by emotions such as laughing, crying, or terror. Cataplexy affects approximately 20% of people who have narcolepsy, and is caused by an autoimmune destruction of hypothalamic neurons that produce the neuropeptide hypocretin (also called orexin), which regulates arousal and has a role in stabilization of the transition between wake and sleep states. Cataplexy without narcolepsy is rare and the cause is unknown.
Polyphasic sleep
Polyphasic sleep is the practice of sleeping during multiple periods over the course of 24 hours, in contrast to monophasic sleep, which is one period of sleep within 24 hours. Biphasic (or diphasic, bifurcated, or bimodal) sleep refers to two periods, while polyphasic usually means more than two. Segmented sleep and divided sleep may refer to polyphasic or biphasic sleep, but may also refer to interrupted sleep, where the sleep has one or several shorter periods of wakefulness, as was the norm for night sleep in pre-industrial societies.
Actigraphy
Actigraphy is a non-invasive method of monitoring human rest/activity cycles. A small actigraph unit, also called an actimetry sensor, is worn for a week or more to measure gross motor activity. The unit is usually in a wristwatch-like package worn on the wrist. The movements the actigraph unit undergoes are continually recorded and some units also measure light exposure. The data can be later read to a computer and analysed offline; in some brands of sensors the data are transmitted and analysed in real time.
Fatal insomnia
Fatal insomnia is an extremely rare neurodegenerative prion disease that results in trouble sleeping as its hallmark symptom. The majority of cases are familial (fatal familial insomnia [FFI]), stemming from a mutation in the PRNP gene, with the remainder of cases occurring sporadically (sporadic fatal insomnia [sFI]). The problems with sleeping typically start out gradually and worsen over time. Eventually, the patient will succumb to total insomnia (agrypnia excitata), most often leading to other symptoms such as speech problems, coordination problems, and dementia.
Sleep study
A sleep study is a test that records the activity of the body during sleep. There are five main types of sleep studies that use different methods to test for different sleep characteristics and disorders. These include simple sleep studies, polysomnography, multiple sleep latency tests (MSLTs), maintenance of wakefulness tests (MWTs), and home sleep tests (HSTs). In medicine, sleep studies have been useful in identifying and ruling out various sleep disorders.
Apparent death
Apparent death is a behavior in which animals take on the appearance of being dead. It is an immobile state most often triggered by a predatory attack and can be found in a wide range of animals from insects and crustaceans to mammals, birds, reptiles, amphibians, and fish. Apparent death is separate from the freezing behavior seen in some animals. Apparent death is a form of animal deception considered to be an anti-predator strategy, but it can also be used as a form of aggressive mimicry.
Dream diary
A dream diary (or dream journal) is a diary in which dream experiences are recorded. A dream diary might include a record of nightly dreams, personal reflections and waking dream experiences. It is often used in the study of dreams and psychology. Dream diaries are also used by some people as a way to help induce lucid dreams. They are also regarded as a useful catalyst for remembering dreams. The use of a dream diary was recommended by Ann Faraday in The Dream Game as an aid to memory and a way to preserve details, many of which are otherwise rapidly forgotten no matter how memorable the dream originally seemed.