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Circadian rhythm sleep disorder
Specialty
Neurology, Chronobiology
Circadian rhythm sleep disorders (CRSD) are a family of sleep disorders which affect the timing of sleep. CRSDs arise from a persistent pattern of sleep/wake disturbances that can be caused either by dysfunction in one's biological clock system, or by misalignment between one's endogenous oscillator and externally imposed cues. As a result of this mismatch, those affected by circadian rhythm sleep disorders have a tendency to fall asleep at unconventional time points in the day. These occurrences often lead to recurring instances of disturbed rest, where individuals affected by the disorder are unable to go to sleep and awaken at "normal" times for work, school, and other social obligations.
Humans, like most living organisms, have various biological rhythms. These biological clocks control processes that fluctuate daily (e.g. body temperature, alertness, hormone secretion), generating circadian rhythms. Among these physiological characteristics, our sleep-wake propensity can also be considered one of the daily rhythms regulated by the biological clock system. Our sleeping cycles are tightly regulated by a series of circadian processes working in tandem, which allow us to experience moments of consolidated sleep during the night and a long wakeful moment during the day. Conversely, disruptions to these processes and the communication pathways between them can lead to problems in sleeping patterns, which are collectively referred to as Circadian rhythm sleep disorders.
Contents
1Normal rhythm
2Diagnosis
3Types
3.1Intrinsic
3.2Extrinsic
4Treatment
5See also
6References
7External links
Normal rhythm
A circadian rhythm is an entrainable, endogenous, biological activity that has a period of roughly twenty-four hours. This internal time-keeping mechanism is centralized in the suprachiasmatic nucleus (SCN) of humans and allows for the internal physiological mechanisms underlying sleep and alertness to become synchronized to external environmental cues, like the light-dark cycle.[1] The SCN also sends signals to peripheral clocks in other organs, like the liver, to control processes such as glucose metabolism.[2] Although these rhythms will persist in constant light or dark conditions, different Zeitgebers (time givers such as the light-dark cycle) give context to the clock and allow it to entrain and regulate expression of physiological processes to adjust to the changing environment. Genes that help control light-induced entrainment include positive regulators BMAL1 and CLOCK and negative regulators PER1 and CRY.[3] A full circadian cycle can be described as a twenty-four hour circadian day, where circadian time zero (CT 0) marks the beginning of a subjective day for an organism and CT 12 marks the start of subjective night.[4]
Humans with regular circadian function have been shown to maintain regular sleep schedules, regulate daily rhythms in hormone secretion, and sustain oscillations in core body temperature.[5] Even in the absence of Zeitgebers, humans will continue to maintain a roughly 24-hour rhythm in these biological activities. Regarding sleep, normal circadian function allows people to maintain balance rest and wakefulness that allows people to work and maintain alertness during the day's activities, and rest at night.[6]
Some misconceptions regarding circadian rhythms and sleep commonly mislabel irregular sleep as a circadian rhythm sleep disorder. In order to be diagnosed with CRSD, there must be either a misalignment between the timing of the circadian oscillator and the surrounding environment, or failure in the clock entrainment pathway.[7] Among people with typical circadian clock function, there is variation in chronotypes, or preferred wake and sleep times, of individuals. Although chronotype varies from individual to individual, as determined by rhythmic expression of clock genes, people with typical circadian clock function will be able to entrain to environmental cues. For example, if a person wishes to shift the onset of a biological activity, like waking time, light exposure during the late subjective night or early subjective morning can help advance one's circadian cycle earlier in the day, leading to an earlier wake time.[8]
Diagnosis
The International Classification of Sleep Disorders classifies Circadian Rhythm Sleep Disorder as a type of sleep dyssomnia. Although studies suggest that 3% of the adult population suffers from a CRSD, many people are often misdiagnosed with insomnia instead of a CRSD. Of adults diagnosed with sleep disorders, an estimated 10% have a CRSD and of adolescents with sleep disorders, an estimated 16% may have a CRSD.[9] Patients diagnosed with circadian rhythm sleep disorders typically express a pattern of disturbed sleep, whether that be excessive sleep that intrudes on working schedules and daily functions, or insomnia at desired times of sleep. Note that having a preference for extreme early or late wake times are not related to a circadian rhythm sleep disorder diagnosis. There must be distinct impairment of biological rhythms that affects the person's desired work and daily behavior. For a CRSD diagnosis, a sleep specialist gathers the history of a patient's sleep and wake habits, body temperature patterns, and dim-light melatonin onset (DLMO).[9] Gathering this data gives insight into the patient's current schedule as well as the physiological phase markers of the patient's biological clock.
The start of the CRSD diagnostic process is a thorough sleep history assessment. A standard questionnaire is used to record the sleep habits of the patient, including typical bedtime, sleep duration, sleep latency, and instances of waking up. The professional will further inquire about other external factors that may impact sleep. Prescription drugs that treat mood disorders like tricyclic antidepressants, selective serotonin reuptake inhibitors and other antidepressants are associated with abnormal sleep behaviors. Other daily habits like work schedule and timing of exercise are also recorded because they may impact an individual's sleep and wake patterns. To measure sleep variables candidly, patients wear actigraphy watches that record sleep onset, wake time, and many other physiological variables. Patients are similarly asked to self-report their sleep habits with a week-long sleep diary to document when they go to bed, when they wake up, etc. to supplement the actigraphy data. Collecting this data allows sleep professionals to carefully document and measure patient's sleep habits and confirm patterns described in their sleep history.[9]
Other additional ways to classify the nature of a patient's sleep and biological clock are the Morningness-Eveningness Questionnaire and the Munich ChronoType Questionnaire, both of which have fairly strong correlations with accurately reporting phase advanced or delayed sleep.[8] Questionnaires like the Pittsburgh Sleep Quality Index (PSQI) and the Insomnia Severity Index (ISI) help gauge the severity of sleep disruption. Specifically, these questionnaires can help the professional assess the patient's problems with sleep latency, undesired early-morning wakefulness, and problems with falling or staying asleep.[9]
Types
Currently, the International Classification of Sleep Disorders (ICSD-3) lists 6 disorders under the category of circadian rhythm sleep disorders.[10]
CRSDs can be categorized into two groups based on their underlying mechanisms: The first category is composed of disorders where the endogenous oscillator has been altered, known as intrinsic type disorders. This category will be referred to as the intrinsic disorder type. The second category consists of disorders in which the external environment and the endogenous circadian clock are misaligned, called extrinsic type CRSDs.
Intrinsic
Delayed sleep phase disorder (DSPD): Individuals who have been diagnosed with delayed sleep phase disorder have sleep-wake times which are delayed when compared to normal functioning individuals. People with DSPD typically have very long periods of sleep latency when they attempt to go to sleep during conventional sleeping times. Similarly, they also have trouble waking up at conventional times.
Advanced sleep phase disorder (ASPD): People with advanced sleep phase disorder exhibit characteristics opposite to those with delayed sleep phase disorder. These individuals have advanced sleep wake times, so they tend to go to bed and wake up much earlier as compared to normal individuals. ASPD is less common than DSPD, and is most prevalent within older populations.
Familial Advanced Sleep Phase Syndrome (FASPS) is linked to an autosomal dominant mode of inheritance. It is associated with a missense mutation in human PER2 that replaces Serine for a Glycine at position 662 (S662G).[11] Families that have this mutation in PER2 experience extreme phase advances in sleep, waking up around 2 AM and going to bed around 7 PM.
Irregular sleep–wake rhythm disorder (ISWRD) is characterized by a normal 24-hr sleeping period. However, individuals with this disorder experience fragmented and highly disorganized sleep that can manifest in the form of waking frequently during the night and taking naps during the day, yet still maintaining sufficient total time asleep. People with ISWRD often experience a range of symptoms from insomnia to excessive daytime sleepiness.
Most common in individuals that are blind and unable to detect light, Non-24-hour sleep–wake disorder (N24SWD) is characterized by chronic patterns of sleep/wake cycles which are not entrained to the 24-hr light-dark environmental cycle. As a result of this, individuals with this disorder will usually experience a gradual yet predictable delay of sleep onset and waking times. Patients with DSPD may develop this disorder if their condition is untreated.
Extrinsic
Shift work sleep disorder (SWSD): Approximately 9% of Americans who work night or irregular work shifts are believed to experience Shift work sleep disorder.[12] Night shift work directly opposes the environmental cues that entrain our biological clock, so this disorder arises when an individual's clock is unable to adjust to the socially imposed work schedule. Shift work sleep disorder can lead to severe cases of insomnia as well as excessive daytime sleepiness.
Jet lag: Jet lag is best characterized by difficulty falling asleep or staying asleep as a result of misalignment between one's internal circadian system and external, or environmental cues. It is typically associated with rapid travel across multiple time zones.[10]
Treatment
Possible treatments for circadian rhythm sleep disorders include:
Chronotherapy, best shown to effectively treat Delayed sleep phase disorder, acts by systematically delaying an individual's bedtime until their sleep-wake times coincide with the conventional 24-hr day.
Light therapy utilizes bright light exposure to induce phase advances and delays in sleep and wake times. This therapy requires 30-60 minutes of exposure to a bright (5,000-10,000 lux) white, blue, or natural light at a set time until the circadian clock is aligned with the desired schedule. [7][13] Treatment is initially administered either upon awakening or before sleeping, and if successful may be continued indefinitely or performed less frequently.[14] Though proven very effective in the treatment of individuals with DSPD and ASPD, the benefits of light therapy on N24SWD, Shift work disorder, and jet lag have not been studied as extensively.
Hypnotics have also been used clinically alongside bright light exposure therapy and pharmacotherapy for the treatment of CRSDs such as Advanced Sleep Phase Disorder.[15] Additionally, in conjunction with cognitive behavioral therapy, short-acting hypnotics also present an avenue for treating co-morbid insomnia in patients suffering from circadian sleep disorders.
Melatonin, a naturally occurring biological hormone with circadian rhythmicity, has been shown to promote sleep and entrainment to external cues when administered in drug form (0.5-5.0mg). Melatonin administered in the evening causes phase advances in sleep-wake times while maintaining duration and quality of sleep. Similarly, when administered in the early morning, Melatonin can cause phase delays. It has been shown most effective in cases of Shift work sleep disorder and Delayed phase sleep disorder, but has not been proven particularly useful in cases of jet lag.[13]
Dark therapy, for example, the use of blue-blocking goggles, is used to block blue and blue-green wavelength light from reaching the eye during evening hours so as not to hinder melatonin production.[16]
See also
Chronobiology
Light effects on circadian rhythm
Phase response curve
Sleep diary
Sleep medicine
Circadian Rhythms
References
^Toh KL (August 2008). "Basic science review on circadian rhythm biology and circadian sleep disorders". Annals of the Academy of Medicine, Singapore. 37 (8): 662–8. PMID 18797559.
^Dibner C, Schibler U, Albrecht U (2010-03-17). "The mammalian circadian timing system: organization and coordination of central and peripheral clocks". Annual Review of Physiology. 72 (1): 517–49. doi:10.1146/annurev-physiol-021909-135821. PMID 20148687.
^Jones CR, Huang AL, Ptáček LJ, Fu YH (May 2013). "Genetic basis of human circadian rhythm disorders". Experimental Neurology. 243: 28–33. doi:10.1016/j.expneurol.2012.07.012. PMC 3514403. PMID 22849821.
^Di Milia L, Waage S, Pallesen S, Bjorvatn B (2013-01-25). Gamble KL (ed.). "Shift work disorder in a random population sample--prevalence and comorbidities". PLOS ONE. 8 (1): e55306. Bibcode:2013PLoSO...855306D. doi:10.1371/journal.pone.0055306. PMC 3555931. PMID 23372847.
^ abDagan Y (February 2002). "Circadian rhythm sleep disorders (CRSD)". Sleep Medicine Reviews. 6 (1): 45–54. doi:10.1053/smrv.2001.0190. PMID 12531141.
^Dijk DJ, Boulos Z, Eastman CI, Lewy AJ, Campbell SS, Terman M (June 1995). "Light treatment for sleep disorders: consensus report. II. Basic properties of circadian physiology and sleep regulation". Journal of Biological Rhythms. 10 (2): 113–25. doi:10.1177/074873049501000204. PMID 7632985.
^Barion A, Zee PC (September 2007). "A clinical approach to circadian rhythm sleep disorders". Sleep Medicine. 8 (6): 566–77. doi:10.1016/j.sleep.2006.11.017. PMC 2679862. PMID 17395535.
^"Blue light has a dark side". Harvard Health Letter. May 2012.
External links
Classification
D
ICD-10: F51.2, G47.2
ICD-9-CM: 327.3, 780.55
MeSH: D021081
Circadian Sleep Disorders Network
An American Academy of Sleep Medicine Review: Circadian Rhythm Sleep Disorders: Part I, Basic Principles, Shift Work and Jet Lag Disorders. PDF, 24 pages. November 2007.
An American Academy of Sleep Medicine Review: Circadian Rhythm Sleep Disorders: Part II, Advanced Sleep Phase Disorder, Delayed Sleep Phase Disorder, Free-Running Disorder, and Irregular Sleep–Wake Rhythm. PDF, 18 pages. November 2007.
An American Academy of Sleep Medicine Report: Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Sleep Disorders, November 1, 2007
NASA Sleep–Wake Actigraphy and Light Exposure During Spaceflight-Long Experiment
v
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Psychophysiology: Sleep and sleep disorders (F51 and G47 / 307.4 and 327)
Sleep stages
Rapid eye movement (REM)
Non-rapid eye movement
Slow-wave
Brain waves
Alpha wave
Beta wave
Delta wave
Gamma wave
K-complex
Mu rhythm
Sensorimotor rhythm
Sleep spindle
Theta wave
Sleep disorders
Dyssomnia
Hypersomnia
Insomnia
Kleine–Levin syndrome
Narcolepsy
Sleep apnea
Central hypoventilation syndrome
Obesity hypoventilation syndrome
Sleep state misperception
Circadian rhythm disorders
Advanced sleep phase disorder
Delayed sleep phase disorder
Irregular sleep–wake rhythm
Jet lag
Non-24-hour sleep–wake disorder
Shift work sleep disorder
Parasomnia
Catathrenia
Night terror
Rapid eye movement sleep behavior disorder
Sleepwalking
Somniloquy
Other
Bruxism
Cyclic alternating pattern
Night eating syndrome
Nocturia
Nocturnal myoclonus
Benign phenomena
Dream
Exploding head syndrome
False awakening
Hypnagogia / Sleep onset
Hypnic jerk
Lucid dream
Nightmare
Nocturnal clitoral tumescence
Nocturnal emission
Nocturnal penile tumescence
Sleep paralysis
Somnolence
Related topics
Bed
Bunk bed
Daybed
Four-poster bed
Futon
Hammock
Mattress
Sleeping bag
Bed bug
Bedding
Bedroom
Bedtime
Bedtime story
Bedtime toy
Biphasic and polyphasic sleep
Chronotype
Dream journal
Excessive daytime sleepiness
Hypnopompic state
Lullaby
Microsleep
Nap
Nightwear
Power nap
Second wind
Siesta
Sleep and creativity
Sleep and learning
Sleep debt
Sleep deprivation
Sleep diary
Sleep hygiene
Sleep induction
Sleep inertia
"Sleeping sickness"1
Sleeping while on duty
Sleepover
Snoring
Somnology
Polysomnography
Sleep medicine
1 Not a sleep disorder.
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Diseases of the nervous system, primarily CNS (G04–G47, 323–349)
… and identify sleepschedules, activities, and environmental factors that might impact sleep as well as strategies to manipulate these factors in ways congruent with improved sleep.… reductions in total sleep time, increased nighttime wakefulness, reduced sleep efficiency, poor subjective sleep quality, long sleep times (>8 hours), and disturbed sleep have all been…
… there is a similar misalignment of the circadian system to the desired sleep and work schedules. For night shift workers, wakefulness is required at a time when the circadian drive for alertness is dissipating …
… a regular sleep-wake schedule and adequate sleep times prior to undergoing the MSLT. Practitioners may consider the use of actigraphy or sleep diaries to document adequate sleep time during… cumulative sleep of any stage. The recommended definition for sleep onset for the maintenance of wakefulness test (MWT) is three consecutive epochs of stage 1 sleep or one epoch of any other stage of sleep.…
… NREM stage 4 are combined as stage N3 . Stage N1 sleep is the typical transition from wakefulness to sleep. It is characterized by low amplitude mixed EEG frequencies in the theta range (4 to 7 Hz) for at …
… For children with a significantly delayed sleep onset or inconsistent sleepschedule, a two-week sleep log with or without actigraphy can be helpful… periods of wakefulness and periods of sleep. As a result, multiple short sleep episodes are spread across the 24-hour day, interspersed with multiple periods of wakefulness.…
English Journal
Evaluating the role of orexins in the pathophysiology and treatment of depression: A comprehensive review.
Shariq AS, Rosenblat JD, Alageel A, Mansur RB, Rong C, Ho RC, Ragguett RM, Pan Z, Brietzke E, McIntyre RS.
Progress in neuro-psychopharmacology & biological psychiatry. 2019 06;92()1-7.
Orexins are neuropeptides that are postulated to play a central role in the regulation of the sleep-wake cycle, appetite, affect, and reward circuitry. The objectives of the current review are to comprehensively evaluate (1) the potential role of orexins in the pathophysiology of major depressive di
The bidirectional impact of sleep and circadian rhythm dysfunction in human ischaemic stroke: A systematic review.
Gottlieb E, Landau E, Baxter H, Werden E, Howard ME, Brodtmann A.
Sleep medicine reviews. 2019 Jun;45()54-69.
Sleep and circadian rhythm disruption are potentially modifiable risk factors and consequences of ischaemic stroke. Pre-clinical evidence suggests a direct effect of sleep and endogenous circadian rhythm dysfunction on lesion volumes and post-stroke recovery. In humans, sleep and stroke literature h
Shift Work, Chronotype, and Melatonin Rhythm in Nurses.
Razavi P, Devore EE, Bajaj A, Lockley SW, Figueiro MG, Ricchiuti V, Gauderman WJ, Hankinson SE, Willett WC, Schernhammer E.
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2019 May;().
Previous studies associated night-shift work with melatonin disruption, with mixed evidence regarding the modulating effects of chronotype (i.e., diurnal preference). 130 active nurses (84 rotating-shift and 46 day-shift workers) in the Nurses' Health Study II wore a head-mounted light meter and col
The Tohoku Journal of Experimental Medicine 234(2), 123-128, 2014
… Along with urbanization of the living environment, the number of patients with circadian rhythm sleepdisorder (CRSD) has been increasing. … There are several treatment candidates for CRSD, such as light therapy, drugs (melatonin and vitamin B12), and sleep hygiene education. … She was given sleep hygiene education together with ramelteon at first and the free-running cycle stopped after treatment day 15. …
THE TOHOKU JOURNAL OF EXPERIMENTAL MEDICINE 216(1), 95-98, 2008-09-01
… Delayed sleep phase syndrome (DSPS) is a circadian rhythm sleepdisorder with a typical onset in the second decade of life. … DSPS is characterized by the sleep-onset insomnia and the difficulty in waking at the desired time in the morning. … They answered anonymous screening questionnaire regarding school schedule, sleep hygiene and symptomatic items of sleep disorders. …
Looking for online definition of sleep-wake schedule disorder in the Medical Dictionary? sleep-wake schedule disorder explanation free. What is sleep-wake schedule disorder? Meaning of sleep-wake schedule disorder medical ...
Information on Sleep-wake Schedule Disorder DefinitionDefinitions - Circadian Sleep Disorders Networkhttps://www.circadiansleepdisorders.org/defs.phpThis disorder causes problems with work and family. There is no schedule or ...
Definitions of terms related to circadian rhythm disorders, including what is circadian rhythm, and what are delayed sleep phase syndrome (DSPS) and non-24-hour sleep-wake disorder (Non-24).