Circadian Rhythm Abnormalities

Abstract

Purpose: This article reviews the recent advances in understanding of the fundamental properties of circadian rhythms and discusses the clinical features, diagnosis, and treatment of circadian rhythm sleep disorders (CRSDs). Recent Findings: Recent evidence strongly points to the ubiquitous influence of circadian timing in nearly all physiologic functions. Thus, in addition to the prominent sleep and wake disturbances, circadian rhythm disorders are associated with cognitive impairment, mood disturbances, and increased risk of cardiometabolic disorders. The recent availability of biomarkers of circadian timing in clinical practice has improved our ability to identify and treat these CRSDs. Summary: Circadian rhythms are endogenous rhythms with a periodicity of approximately 24 hours. These rhythms are synchronized to the physical environment by social and work schedules by various photic and nonphotic stimuli. CRSDs result from a misalignment between the timing of the circadian rhythm and the external environment (eg, jet lag and shift work) or a dysfunction of the circadian clock or its afferent and efferent pathways (eg, delayed sleep-phase, advanced sleep-phase, nonY24-hour, and irregular sleep-wake rhythm disorders). The most common symptoms of these disorders are difficulties with sleep onset and/or sleep maintenance and excessive sleepiness that are associated with impaired social and occupational functioning. Effective treatment for most of the CRSDs requires a multimodal approach to accelerate circadian realignment with timed exposure to light, avoidance of bright light at inappropriate times, and adherence to scheduled sleep and wake times. In addition, pharmacologic agents are recommended for some of the CRSDs. For delayed sleep-phase, nonY24-hour, and shift work disorders, timed low-dose melatonin can help advance or entrain circadian rhythms; and for shift work disorder, wakeenhancing agents such as caffeine, modafinil, and armodafinil are options for the management of excessive sleepiness.

Stress, Sleep and Recovery in Elite Soccer: A Critical Review of the Literature

“…Circadian rhythms are endogenous rhythms with a periodicity of approximately 24 h [93]. The suprachiasmatic nucleus is synchronised by various photic and nonphotic stimuli, primarily with the environment by the lightdark cycle, and to a lesser degree by other environmental conditions such as social routine, physical exercise and food intake [35,36,93].…”

The Relationship Between Sleep Disorders and Quality of Life in Rotating Shift Workers at a Textile Factory

“…Night shifts result in lack of coordination in body's internal circadian rhythm with environmental factors regulating the body's biologic clock such as light-dark cycle, and this leads to disruption of normal physiological activity and psychological difficulties (14,15). Changing shift work from day to evening and night causes a person to regulate his/her sleep-wake cycle in accordance with the job duties and not based on the natural rhythms and physiological body.…”

Circadian Rhythm Sleep Disorders

“…If polysomnography is performed during normal sleep time in patients with ASPD, sleep architecture and duration will be normal, but if performed at more conventional times, NREM sleep duration, particularly slow wave sleep, is reduced [27]. Treatment approaches for ASPD include chronotheraphy, timed bright light therapy in the early evening (between 7:00 pm and 9:00pm), avoiding light early in the morning, and pharmacotherapy with sedative-hypnotics or administration of melatonin in the early morning [28]. However, there is little evidence to support the effectiveness of pharmacological therapy [29].…”

“…These treatments include timed exposure to light, avoidance of bright light at inappropriate times, scheduled sleep/wake times, and sometimes pharmacologic agents [28]. Light is the most powerful zeitgeber, or entraining agent of the human circadian rhythm, and correctly timed light exposure, sometimes combined with timed administration of melatonin is useful in treating the CRSD's delayed sleep phase, advanced sleep phase, free-running, irregular sleep wake, jet lag, and shift work [29].…”