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“It is widely known that most of oral diseases are chronic process and are closely related to individual manner, so that people occasionally call them “life-style related diseases”. All of us modern people live in

a “24/7” society and Cell Cycle inhibitor we sleep at night and wake during the day under the influence of social schedules. However, even if we do not have a schedule or need to wake at a set time, our sleep and wake episodes spontaneously appear at habitual bed- and wake-up times. Daily rhythms in physiological functions are observed in body temperature, hormone secretions, cardiovascular regulations and so on, including oral functions. The Saliva flow rate and concentrations of salivary contents are subject to marked variation based on circadian manner (Fig. 1A) [1] that may affect on the dental caries risks by means of buffering pH fluctuation and keeping tooth remineralization equilibrium. Human dentin has well defined growth lines with a period of about 24-h, suggesting a circadian variation in odontoblast function such as the synthesis and secretion of dentin matrix [2]. The hypothalamic suprachiasmatic nuclei see more (SCN) are our principal circadian clock, coordinating general daily cycles of physiology and behavior. In the last decade,

it has been suggested that several physiological variations such as bone remodeling, hypothalamus–pituitary hormone regulations, metabolic status in the liver and so on might be attributable to circadian clock functions in each organs on cellular and molecular level (Fig. 1B) [3] and [4]. When those tissue-specific local clocks are in disorganized each other and/or dissociated from the central clock SCN, it would not only have a major impact on health in each organs but also cause sleep–wake, mental and the other psychiatric disorders [5]. That is always the case in oral disease. Regular life-styles with orchestrated physiological circadian rhythms lead to prevent common disease, vice Amoxicillin versa by strengthening circadian rhythm it would assist to establish

the suitable life-style for individuals. In this review, we will present circadian control of sleep and wakefulness as well as suitable environmental settings for recovery of circadian rhythm sleep disorders, particularly in individuals with pervasive developmental disorders. Recently in Japan, considerable attention has been paid to individuals showing social maladjustment as well as withdrawal from social situations and activity (Hikikomori). The phenomenon of Hikikomori is defined as “a state of social withdrawal for more than 6 months, not going to work or school, except for occasionally going out, but not communicating with people besides family members” [6]. Koyama et al. (2010) conducted a survey from 2002 to 2006 to clarify the lifetime prevalence of Hikikomori and psychiatric comorbidities of Hikikomori among a community population aged 20–49 years old (n = 1660). They found that 1.