Since the introduction of the first edition of International Classification of Sleep Disorders: Diagnostic and Coding Manual(ICSD-1)in 1990,national and international meetings were held to openly discuss the ongoing developments of sleep disorders and a new International Classification of Sleep Disorders: Diagnostic and Coding Manual(ICSD-2)was published in 2005.Compared with ICSD-1,the classification of ICSD-2 was developed in a manner compatible with new International Classification of Diseases(ICD-9 and ICD-10)and formed a coordinated system of International Classification of Diseases.The updated version was characterized by the significant improvements of its logicality and clinical practicability,and was more consistent with the International Classification of Disease.The contents of ICSD-2 were introduced in this article.

Brief introduction to second edition of International Classification of Sleep Disorders:Diagnostic and Coding Manual

Circadian (∼24-hour) timing systems pervade all kingdoms of life and temporally optimize behavior and physiology in humans. Relatively recent changes to our environments, such as the introduction of artificial lighting, can disorganize the circadian system, from the level of the molecular clocks that regulate the timing of cellular activities to the level of synchronization between our daily cycles of behavior and the solar day. Sleep/wake cycles are intertwined with the circadian system, and global trends indicate that these, too, are increasingly subject to disruption. A large proportion of the world's population is at increased risk of environmentally driven circadian rhythm and sleep disruption, and a minority of individuals are also genetically predisposed to circadian misalignment and sleep disorders. The consequences of disruption to the circadian system and sleep are profound and include myriad metabolic ramifications, some of which may be compounded by adverse effects on dietary choices. If not addressed, the deleterious effects of such disruption will continue to cause widespread health problems; therefore, implementation of the numerous behavioral and pharmaceutical interventions that can help restore circadian system alignment and enhance sleep will be important.

Circadian Rhythm and Sleep Disruption: Causes, Metabolic Consequences, and Countermeasures

Circadian rhythms are near 24-h patterns of physiology and behaviour that are present independent of external cues including hormones, body temperature, mood, and sleep propensity. The term ‘ circadian misalignment ’ describes a variety of circumstances, such as inappropriately timed sleep and wake, misalignment of sleep/wake with feeding rhythms, or misaligned central and peripheral rhythms. The predominance of early research focused on misalignment of sleep to the biological night. However, discovery of clock genes and the presence of peripheral circadian oscillators have expanded the defi nitions of misalignment. Experimental studies conducted in animal models and humans have provided evidence of potential mechanisms that link misalignment to negative outcomes. These include dysregulation of feeding behaviours, changes in appetite stimulating hormones, glucose metabolism and mood. This review has two foci: (1) to describe how circadian misalignment has been defi ned and evaluated in laboratory and fi eld experiments, and (2) to describe evidence linking different types of circadian misalignment to increased risk for physical (cardiovascular disease, diabetes, obesity, cancer) and psychiatric (depression, bipolar, schizophrenia, attention defi cit) disorders. This review will describe the role of circadian misalignment as a risk factor for disease in the general population and in clinical populations, including circadian rhythm sleep disorders and psychiatric disorders.

Circadian misalignment and health

Being a morning person is a behavioural indicator of a person's underlying circadian rhythm. Using genome-wide data from 697,828 UK Biobank and 23andMe participants we increase the number of genetic loci associated with being a morning person from 24 to 351. Using data from 85,760 individuals with activity-monitor derived measures of sleep timing we find that the chronotype loci associate with sleep timing: the mean sleep timing of the 5% of individuals carrying the most morningness alleles is 25 min earlier than the 5% carrying the fewest. The loci are enriched for genes involved in circadian regulation, cAMP, glutamate and insulin signalling pathways, and those expressed in the retina, hindbrain, hypothalamus, and pituitary. Using Mendelian Randomisation, we show that being a morning person is causally associated with better mental health but does not affect BMI or risk of Type 2 diabetes. This study offers insights into circadian biology and its links to disease in humans.

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Genome-wide association analyses of chronotype in 697,828 individuals provides insights into circadian rhythms.

Sleep disturbances comparable with insomnia occur in up to 80% of people with schizophrenia, but very little is known about the contribution of circadian coordination to these prevalent disruptions.

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Sleep and circadian rhythm disruption in schizophrenia

https://www.innovative-eyewear.com/wp-content/uploads/2014/12/Blue-Blocker-glasses-melatonin-LED-Teenager.pdf

Blue Blocker Glasses as a Countermeasure for Alerting Effects of Evening Light-Emitting Diode Screen Exposure in Male Teenagers

Background Irregular sleep–wake cycles and cognitive impairment are frequently observed in schizophrenia, however, how they interact remains unclear. Aims To investigate the repercussions of circadian rhythm characteristics on cognitive performance and psychopathology in individuals with schizophrenia. Method Fourteen middle-aged individuals diagnosed with schizophrenia underwent continuous wrist actimetry monitoring in real-life settings for 3 weeks, and collected saliva samples to determine the onset of endogenous melatonin secretion as a circadian phase marker. Moreover, participants underwent multiple neuropsychological testing and clinical assessments throughout the study period. Results Sleep–wake cycles in individuals with schizophrenia ranged from well entrained to highly disturbed rhythms with fragmented sleep epochs, together with delayed melatonin onsets and higher levels of daytime sleepiness. Participants with a normal rest–activity cycle (objectively determined by high relative amplitude of day/night activity) performed significantly better in frontal lobe function tasks. Stepwise regression analysis revealed that relative amplitude and age represented the best predictors for cognitive performance (Stroop colour–word interference task, Trail Making Test A and B, semantic verbal fluency task), whereas psychopathology (Positive and Negative Syndrome Scale) did not significantly correlate with either cognitive performance levels or the quality of sleep–wake cycles. Conclusions Consolidated circadian rhythms and sleep may be a prerequisite for adequate cognitive functioning in individuals with schizophrenia.

/pdf/sleep-wake-cycles-and-cognitive-functioning-in-schizophrenia-2l6u5yif4d.pdf

Sleep-wake cycles and cognitive functioning in schizophrenia

Sleep-onset and maintenance insomnia is a common symptom in schizophrenic patients regardless of either their medication status (drug-naive or previously treated) or the phase of the clinical course (acute or chronic). Regarding sleep architecture, the majority of studies indicate that non-rapid eye movement (NREM), N3 sleep and REM sleep onset latency are reduced in schizophrenia, whereas REM sleep duration tends to remain unchanged. Many of these sleep disturbances in schizophrenia appear to be caused by abnormalities of the circadian system as indicated by misalignments of the endogenous circadian cycle and the sleep-wake cycle. Circadian disruption, sleep onset insomnia and difficulties in maintaining sleep in schizophrenic patients could be partly related to a presumed hyperactivity of the dopaminergic system and dysfunction of the GABAergic system, both associated with core features of schizophrenia and with signaling in sleep and wake promoting brain regions. Since multiple neurotransmitter systems within the CNS can be implicated in sleep disturbances in schizophrenia, the characterization of the neurotransmitter systems involved remains a challenging dilemma.

Sleep and circadian rhythm dysregulation in schizophrenia.

Environmental light synchronizes the primary mammalian biological clock in the suprachiasmatic nuclei, as well as many peripheral clocks in tissues and cells, to the solar 24-hour day. Light is the strongest synchronizing agent (zeitgeber) for the circadian system, and therefore keeps most biological and psychological rhythms internally synchronized, which is important for optimum function. Circadian sleep-wake disruptions and chronic circadian misalignment, as often observed in psychiatric and neurodegenerative illness, can be treated with light therapy. The beneficial effect on circadian synchronization, sleep quality, mood, and cognitive performance depends on timing, intensity, and spectral composition of light exposure. Tailoring and optimizing indoor lighting conditions may be an approach to improve wellbeing, alertness, and cognitive performance and, in the long term, producing health benefits.

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Light and chronobiology: implications for health and disease.

Individuals with borderline personality disorder (BPD) frequently suffer from sleep disturbances. The authors investigated circadian rhythms, sleep, and well-being in women with BPD in their habitual life conditions during 3 weeks with morning light therapy (LT) and 3 weeks without LT (oLT). Sleep–wake cycles were measured using wrist actimetry, proximal skin temperature as an indirect index of relaxation, as well as weekly salivary melatonin to document the internal circadian rhythm phase. Questionnaires assessed clinical state throughout the 6-week protocol. Ten matched healthy women followed the same 6-week protocol without light treatment. Women with BPD had significantly worse subjective sleep quality and reduced daytime alertness compared to controls. Sleep–wake cycles in BPD ranged from highly disturbed to extremely regular patterns. Melatonin and proximal skin temperature profiles revealed appropriate synchronization of the circadian system with the sleep–wake cycle in most BPD women and in all controls. Morning LT significantly phase-advanced activity in BPD compared to oLT, shortened sleep duration, decreased movement time, and increased skin temperature during sleep (a marker of relaxation). Although general depression scores and borderline symptoms did not change, daytime alertness improved with morning LT, and atypical depression scores were attenuated. Morning LT is a potential adjunct treatment for BPD.

Vivien Bromundt

Papers

Blue Blocker Glasses as a Countermeasure for Alerting Effects of Evening Light-Emitting Diode Screen Exposure in Male Teenagers

Sleep-wake cycles and cognitive functioning in schizophrenia

Sleep and circadian rhythm dysregulation in schizophrenia.

Light and chronobiology: implications for health and disease.

Circadian sleep-wake cycles, well-being, and light therapy in borderline personality disorder.