Light therapy (also called light treatment or phototherapy) involves scheduled exposure to bright artificial light. Evidence-based treatments for sleep disorders especially for circadian rhythm sleep disorders include light therapy and pharmacotherapy. In clinical practice, many of patients with sleep problems tend to impair circadian rhythmicity. Considering that light is the most potent entraining agent of circadian rhythm, careful use of light therapy can be recommended for patients with several kinds of sleep disorders. I briefly review the possible therapeutic mechanisms and clinical applications of light therapy, focusing on circadian sleep disorders.
Circadian Rhythm ; Humans ; Light ; Phototherapy ; Sleep Wake Disorders ; Sleep Wake Disorders, Circadian Rhythm

Excessive daytime sleepiness in childhood might be abnormal phenomenon and often related to the sleep disorders or insufficient sleep duration. The most common cause of excessive daytime sleepiness would be insufficient sleep. However, narcolepsy, idiopathic hypersomnia, circadian rhythm sleep disorders, medication, medical illness and other sleep disorders that could cause insomnia and poor quality of sleep also result in excessive daytime sleepiness. The misdiagnosed and untreated excessive daytime sleepiness in childhood can lead to serious developmental and educational problem.
Child ; Humans ; Hypersomnolence, Idiopathic ; Narcolepsy ; Sleep Wake Disorders ; Sleep Wake Disorders, Circadian Rhythm ; Sleep Initiation and Maintenance Disorders

OBJECTIVES: It is a paradox that sleep technicians are at risk of shift work sleep disorder to help diagnose other people's sleep disorder. Until now, there have been no guidelines for scheduling shifts for sleep technicians. The purpose of this study was to survey the current shift schedule of sleep technicians. METHODS: We performed a nationwide survey of work schedules for sleep laboratories. We sent email questionnaires to sleep technicians working in university-affiliated hospitals. Information regarding starting time and duration of shift, duty on-duty off pattern for the past month, and rotation and number of sleep technicians in the sleep labs were collected. RESULTS: We received responses from 29 sleep labs. Among the 25 labs which had designated sleep technicians, three labs had night shift schedules mixed with day work on a weekly basis and the remaining 22 labs had night only shift schedule. In cases of night only shift schedules, 11 labs alternated from night shift to day shift works or vice versa every 3 months to 3 years, while the remaining 11 labs had fixed schedules without daytime rotation. Number of night shift was four or less per week, with shift durations of 9–19 hours. CONCLUSIONS: The current policies regarding scheduling shifts varied vastly depending on individual sleep labs. We found that some labs had shift schedules with long work time, quick returns, or permanent night shifts, which are generally not recommended. Further studies are needed to develop consensus guidelines for scheduling shift of sleep technicians.
Appointments and Schedules ; Consensus ; Electronic Mail ; Korea ; Sleep Disorders, Circadian Rhythm ; Sleep Wake Disorders

A total of 85 sleep disorders are described in the International Classification of Sleep Disorders, 2nd ed. Knowledge about those sleep disorders will be essential not only for good and healthy sleep but also for maintaining adequate physical and mental function during daytime. Sleep medicine has a relatively short history compared to other medical fields, thus, many sleep disorders are not familiar to the general public and even to physicians. In this small review about various sleep disorders, I will briefly introduce basic concepts about insomnia, sleep-related breathing disorder, hypersomnia, circadian rhythm sleep disorders, parasomnia and sleep-related movement disorders. These sleep disorders are frequently encountered in clinical settings, and understanding them will give us insight about the basic mechanism of sleep-wake states.
Classification ; Diagnosis ; Disorders of Excessive Somnolence ; Movement Disorders ; Parasomnias ; Respiration ; Sleep Wake Disorders* ; Sleep Disorders, Circadian Rhythm ; Sleep Initiation and Maintenance Disorders

BACKGROUND: Although actigraphy has been used to evaluated sleep-wake patterns and quality of sleep disorders patients, its usefulness in obstructive sleep apnea syndrome (OSAS) and primary insomnia is unclear. To investigate the value of actigraphy in OSAS and differentiating OSAS from primary insomnia, night polysomnography (PSG) and actigraphy were performed simultaneously. METHODS: 31 OSAS patients and 21 primary insomnia patients were included (16 females, 36 males). Sleep latency, total sleep time, sleep efficiency and actual wake time, movement and fragmentation index (MFI) were obtained in actigraphy and compared with PSG results. Spearmann correlation analysis and Mann-Whitney U test were used. RESULTS: The sleep efficiency and total sleep time are highly correlated in PSG and actigraphy (p<0.05, p<0.01). Respiratory disturbance index and arousal index in PSG was relatively correlated with MFI in actigraphy (p<0.05). Sleep latency is not correlated in PSG and actigraphy (p>0.05). OSAS had a significantly higher movement and fragmentation index (MFI) than that of primary insomnia (p<0.05) CONCLUSIONS: Actigraphy is a useful and convenient test in differentiating OSAS from insomnia as well as sleep-wake cycle disorders.
Actigraphy* ; Arousal ; Female ; Humans ; Polysomnography* ; Sleep Apnea, Obstructive* ; Sleep Wake Disorders* ; Sleep Disorders, Circadian Rhythm ; Sleep Initiation and Maintenance Disorders*

Smith-Magenis syndrome (SMS) (OMIM #182290) is a rare genetic disorder with a prevalence of 1 in 25 000 live births. Approximately 90% of SMS patients have harbored a 3.7 Mb interstitial 17p11.2 deletion involving the RAI1 gene, while 10% of cases have carried pathogenic variants of the RAI1 gene. SMS is characterized by sleep disturbance, intellectual impairment, developmental delay, craniofacial and cardiovascular anomalies, obesity, self injury, aggressive and autistic-like behaviors. Most SMS patients have sleep disorders such as short total sleep time, frequent night waking, short sleep onset, and early morning waking. The sleep disturbance may aggravate with age and persist throughout life. Three mechanisms have been delineated. The first concern was the abnormal secretion of melatonin, with high levels during daytime and low levels at night. Evaluation of the integrity of the intrinsically photosensitive retinal ganglion cell (ipRGC)/melanopsin system has found that SMS patients showed dysfunction in the sustained component of the pupillary light responses to blue light. Synchronization of daily melatonin profile and its photoinhibition are dependent on the activation of melanopsin. Dysfunction of the retina-melanin system may be one of the causes of melatonin spectrum disorders. Secondly, dysregulation of circadian rhythm gene expression has also been noted in mice and SMS patients. Finally, there may be association between sleep deprivation symptoms and DNA methylation patterns, which has provided new insights for SMS-associated sleep disorders and symptoms alike. Treatment for SMS-related sleep disorders is administered primarily through medications like melatonin tablets, which can alleviate insomnia-related sleep difficulties, in particular externalizing behavior in children. Researchers are also actively exploring other treatments for SMS currently.
Animals ; Circadian Rhythm ; Humans ; Melatonin ; Mice ; Sleep ; Sleep Wake Disorders/genetics* ; Smith-Magenis Syndrome/genetics*

Actigraphy is a method for measuring activity with computerized wristwatch like devices. During the several decades, technological advances have improved the availability of these devices, with miniaturizing their size and increasing memory capacities and detection sensitivity. Compared with polysomnography, the gold standard for evaluation of sleep, actigraphy has unique advantages which are less expensive, noninvasive, less limited in time of recording, and more conductive to repeated measures. Now, actigraphy is used increasingly in clinical practice and research for sleep and other circadian rhythm abnormalities. This paper includes the basic technology and algorithms of actigraphy, reliability and validity issues, and general consideration for applications. Also it reviews the current literatures regarding use of actigraphy in sleep disorders including insomnia, obstructive sleep apnea, and periodic limb movement disorder and other psychiatric disorders related to alteration of circadian rhythm.
Actigraphy ; Circadian Rhythm ; Memory ; Nocturnal Myoclonus Syndrome ; Polysomnography ; Reproducibility of Results ; Sleep Apnea, Obstructive ; Sleep Wake Disorders ; Sleep Initiation and Maintenance Disorders

OBJECTIVES: The purpose of this study was to investigate(1)the differences in the sleep pattern, job satisfaction, the quality of life between the rotating shift work nurses and the nurses on a fixed day schedule and (2)the effects of the individual(circadian rhythm and personality)and the work system factors on the job satisfaction and the quality of life. METHODS: Sleep Questionnaire, Korean translation of Composite Scale(KtCS) Job Satisfaction Index, General Health Questionnaire, Eysenck's Personality Questionnaire were administered to 85 rotating shift work nurses(the rotating group)and 70 nurses on a fixed day schedule(the daytime group) We compared the weekday sleep pattern, the frequency of sleep disorders during the last month, circadian rhythm patterns, job satisfaction, and the quality of life between the two groups. Also, we conducted the stepwise multiple regression analysis, where the independent variables were circadian rhythm, work schedule, extroversion, and neurotism and the dependent variables were the job satisfaction and the quality of life. RESULTS: Between the two groups, there were significant differences in the sleep pattern including the regularity of sleep and the frequency and duration of naps. The rotating group had more frequent sleep problems, poorer job satisfaction and quality of life as compared with the daytime group. The job satisfaction and quality of life were poorer in the nurses who were on a rotating shift work schedule and who had higher neurotic trend. On contrary, The job satisfaction and the quality of life were better in those who were on a fixed daytime shift work schedule and who had more an extroversive trend. However, the circadian rhythm had no significant effect on the job satisfaction and quality of life. CONCLUSIONS: The sleep pattern, job satisfaction, and the quality of life were significantly poorer in the rotating group than in the daytime group, as expected. In terms of individual factors which determine the job satisfaction and quality of life, the personality dimensions had a significant effect, whereas the circadian rhythm did not. These results suggest that the circadian rhythms of shift workers may be realigned and that personality characteristics may be an important factor in coping with shift work.
Appointments and Schedules* ; Circadian Rhythm ; Extraversion (Psychology) ; Job Satisfaction* ; Quality of Life* ; Surveys and Questionnaires ; Sleep Wake Disorders

PURPOSE: The purpose of this study was to identify quality of sleep and health-promoting behaviors in rotating-shift nurses and to explore the influence of health promoting behaviors on quality of sleep. METHOD: Participants were 161 staff nurses working in an irregular three shift system in one of three general hospitals located in Kyungpook province. Data were collected using the Pittsburgh Sleep Quality Index and the Health Promoting Lifestyle Profile-II and were analyzed using hierarchical multiple regression analysis. RESULTS: The majority of the participants had very poor quality of sleep and performed a low level of health promoting behaviors. In terms of health promoting behaviors, nutrition and stress management significantly influenced quality of sleep of these nurses. CONCLUSION: Results indicate the importance of encouraging rotating-shift nurses to enhance their health promoting behaviors in order to improve quality of sleep.
Circadian Rhythm ; Gyeongsangbuk-do ; Health Promotion ; Health Status ; Hospitals, General ; Life Style ; Sleep Wake Disorders

PURPOSE: The purpose of this study was to identify the factors affecting shiftwork tolerance among nurses and provide basic data, ultimately, in formulating a plan for improving their shiftwork tolerance. METHODS: The participants were 317 nurses who were working at three general hospitals in Daejeon and Seoul. Data analyzed t-test, ANOVA, correlation analysis, and regression analysis using SPSS 20.0 program. RESULTS: As for the sub-areas of shiftwork tolerance for the respondents, more than a half of nurses working at shifts suffered from insomnia, felt drowsy, complained of chronic fatigue, and were at the anxious and depressed state. Shiftwork tolerance differed by the daily intake of coffee and exercise. Shiftwork tolerance was significantly positively correlated with sleep-wake habits, hardiness, and flexibility and negatively correlated with a languidity. Regression analysis revealed that shiftwork tolerance was affected by age, sleep-wake habits, languidity, flexibility, and hardiness. CONCLUSION: To put the results, nurses had shiftwork tolerance affected by sleep-wake habits, languidity, and hardiness. It is therefore necessary to make a scheme for allowing nurses to improve hardiness and flexibility and decrease the languidity with the objective of improving their shiftwork tolerance.
Circadian Rhythm ; Coffee ; Fatigue ; Hospitals, General ; Pliability ; Seoul ; Sleep Initiation and Maintenance Disorders ; Sleep Wake Disorders ; Surveys and Questionnaires ; Work Schedule Tolerance