OBJECTIVE: Melatonin aids in the synchronization of the circadian rhythm to the external environment. Few studies have tried to elucidate the relationship between melatonin and obstructive sleep apnea syndrome (OSAS). These often include few patients, do not differentiate between OSAS severity and/or do not analyse a 24-h melatonin profile. This study set out to investigate disease severity dependent differences in 24-h salivary melatonin secretion of OSAS patients compared to a reference population in a retrospective design.
METHODS: 24-h salivary melatonin profiles of 169 OSAS patients were analysed (55 light, 66 moderate, 48 severe) as well as 91 reference patients. Several aspects of the melatonin curve were analysed and stratified according to OSAS severity. Parameters included: dim light melatonin onset (DLMO), time of returning below DLMO (DLMOoff), peak melatonin concentration and time, and total melatonin exposure.
RESULTS: Significant effects were corrected for confounding by age and sex using linear regression. Our analysis shows that, compared to reference and in a disease dependent manner, OSAS patients have a significantly lower 24-h melatonin curve, lower melatonin peak concentration, lower total melatonin exposure and a smaller proportion of patients reach DLMO. The differences in peak melatonin production and total melatonin exposure were resistant to confounding by age and/or sex.
CONCLUSIONS: This study describes clear OSAS severity dependent abnormalities in melatonin production in OSAS patients, independent of sex and/or age. Future research should indicate whether oral melatonin supplementation has beneficial effects in OSAS patients with attenuated endogenous melatonin production.

Chronic spontaneous urticaria (CSU) is a dermatological disorder accompanied by itching that greatly affects the quality of life and quality of sleep. Therefore, it is assumed that CSU patients consequently experience reduced melatonin secretion and lower values of serum or salivary melatonin. This pilot study included 20 patients with CSU (chronic urticaria of unknown etiology that lasts for more than 6 weeks) and 10 healthy controls. All subjects were examined by a dermatovenereologist-allergist, as well as an oral pathologist, to exclude oral pathological conditions. Salivary melatonin levels were determined by ELISA and all subjects completed a standardized Dermatology Life Quality Index questionnaire and Pittsburgh Sleep Quality Index on the same day they gave a saliva sample for analysis. According to our results, 86% of CSU patients had decreased values of salivary melatonin, and lower salivary melatonin values significantly correlated with a reduced quality of life in CSU patients. This study was the first to analyze melatonin in CSU patients, also suggesting a possible new therapeutic option for the treatment of CSU.

OBJECTIVE: Anesthesia has been shown to disrupt the circadian rhythm. Recovery of the circadian rhythm after general anesthesia might help alleviate symptoms of insomnia and postoperative delirium. We hypothesized that recovery of the circadian rhythm is faster after total knee arthroplasty (TKA) with desflurane than with sevoflurane. This study compared the influence of sevoflurane versus desflurane anesthesia on the postoperative circadian rhythm of melatonin in adults undergoing TKA.
METHODS: Single-center, prospective, randomized, controlled, open-label study.
METHODS: This study involved adult patients undergoing TKA at a university hospital in Japan from May 1, 2018 to December 31, 2019. The primary outcome of the study was the comparison of the effect of sevoflurane and desflurane on the circadian rhythm of salivary melatonin for 3 days postoperatively. The secondary outcomes were postoperative fatigue and sleep quality for 3 days postoperatively.
RESULTS: Twenty-eight patients (American Society of Anesthesiologists physical status of I or II) were scheduled for TKA and randomized to receive sevoflurane (n = 14) or desflurane (n = 14) anesthesia. There was no significant difference in the melatonin concentration between the sevoflurane and desflurane groups. The salivary melatonin concentration after sevoflurane or desflurane anesthesia was significantly higher at 9:00 p.m. on a postoperative day (POD)0 and POD1 than on POD3 (P < .05). Patients in the desflurane group had significantly greater fatigue than those in the sevoflurane group at 7:00 a.m. and 12:00 p.m. on POD3 (P < .05). Patients in the sevoflurane group had a deeper sleep than those in the desflurane group on POD0 (P < .05). In the sevoflurane group, the sleep time during the night of POD2 was longer than that on POD0 (6.1 vs 4.2 hours, P < .05).
CONCLUSIONS: Under the current study conditions, desflurane was equivalent to sevoflurane in terms of the postoperative salivary melatonin concentration and sleep disturbance after TKA but not in terms of recovering the postoperative circadian rhythm.

UNASSIGNED: Periodontitis is an inflammatory disease in which periodontal tissues are damaged as a result of an imbalance in the oxidant/antioxidant systems. Melatonin is one hormone that controls circadian rhythms and is also an antioxidant and immune modulator.
UNASSIGNED: The present study was aimed to evaluate the effect of scaling and root planing (SRP) on salivary melatonin levels (SM) in patients with periodontal disease.
UNASSIGNED: A single-center clinical trial was conducted to evaluate the effect of SRP on SM levels in patients with periodontal disease.
UNASSIGNED: Forty-five participants of age 30-60 years were equally divided into three groups: 15 healthy participants, 15 participants with gingivitis, and 15 participants with periodontitis. Unstimulated salivary samples were collected from all the participants at baseline and 1 month after SRP from participants of gingivitis and periodontitis group and SM levels were determined by commercially available ELISA kit.
UNASSIGNED: Group comparisons were made using t-test. The level of significance was set at a P < 0.05 for all tests.
UNASSIGNED: SM levels were significantly lower in the chronic periodontitis group. There was a significant improvement in clinical parameters and SM levels in both chronic periodontitis and gingivitis groups after SRP.
UNASSIGNED: This study determined that there is a negative correlation between SM levels and the severity of periodontal disease and showed a significant increase in SM levels after SRP, suggesting that melatonin might have a protective role against periodontal disease and can be considered as an effective biomarker.

Future automotive interior lighting might have the potential to go beyond decorative purposes by influencing alertness, circadian physiology, and sleep. As the available space in the interior of an automobile for lighting applications is limited, understanding the impact of various luminous surface sizes on non-image-forming effects is fundamental in this field. In a laboratory study using a within-subject design, 18 participants were exposed to two bright light conditions with different solid angles and one dim light condition in a balanced, randomized order during the course of the evening. Our results demonstrate that both light conditions significantly increased subjective alertness and reduced salivary melatonin concentration but not cognitive performance compared to dim light. The solid angle of light exposure at constant corneal illuminance only affected visual comfort. While subjective alertness can be increased and melatonin can be attenuated with rather small luminaires, larger solid angles should be considered if visual comfort is a priority.

UNASSIGNED: Melatonin is an indolamine that is primarily secreted by the pineal gland. It has immunomodulatory as well as antioxidant properties. It is a potent anti-oxidant that protects against inflammation and cellular damage caused by reactive oxygen species, also has potent angiogenic function that adds on to the benefits of melatonin. As a result of these actions, melatonin may be useful as an adjuvant in the treatment of various conditions in the oral cavity. The aim of this study is to systematically evaluate the role of melatonin in periodontal disease.
UNASSIGNED: An extensive review of the scientific literature was carried out using PubMed, Science Direct, Google Scholar and the Cochrane base. Research articles were collected upto December 2017.
UNASSIGNED: Melatonin may have beneficial effects in certain inflammatory oral pathologies, mainly periodontal diseases where they inhibit bone resorption destroy reactive oxygen species, stimulates osteoblastic differentiation. Salivary melatonin could also act as a risk indicator for periodontal diseases.
UNASSIGNED: Many studies showed that the melatonin levels in GCF, Saliva, Serum of patients suffering from chronic periodontitis is lowered suggesting that may play a pivotal role in protecting the tissue from damage caused by oxidative stress. However, there exists no data on the concentration needed, method of application for potential benefits. Randomized clinical trials in this field are needed to fill the lacunae and better improve our understanding.

OBJECTIVE: To compare morning and evening salivary melatonin levels, sleep quality and chronotype between nurses working fixed day shifts and those working rotating night shifts.
BACKGROUND: Rotating night shift work is an inevitable part of nursing and is a major reason for disrupted sleep.
METHODS: Cross-sectional comparative design.
METHODS: We used cluster sampling to recruit 520 female nurses working fixed day and rotating night shifts in the United Arab Emirates.
METHODS: Morning and evening melatonin were measured from corresponding saliva samples. The Pittsburgh Sleep Quality Index used to evaluate sleep quality and self-assessment of preferred circadian times was used to assess participants\' chronotypes. Data were collected between October 2017-December 2018.
RESULTS: Rotating night shift nurses had significantly lower evening melatonin compared with the fixed day shift group. No significant difference was found in sleep quality between the groups, although more participants in the rotating night shift group (N = 110, 42.31%) expressed better sleep quality than those in the fixed day group (N = 90, 36.00). Participants in the rotating night shift group expressed better subjective sleep, longer sleep duration, less disturbed sleep and better daily function (p > .05) than the fixed day group. Rotating night shift participants were more likely to have evening or intermediate chronotypes and more likely to report alignment of shift work to their chronotype compared with fixed day shift participants (p = .001). Longer shift duration, marital status and city location were associated with reduced evening melatonin among nurses on rotating night shifts.
CONCLUSIONS: Rotating night shift nurses showed evidence of better sleep than those from the fixed day shift. Proper shift assignment, chronotype and alignment with shift work appeared to produce better sleep quality.
CONCLUSIONS: Organizational policy must consider a novel model for work schedules that allow adequate off-duty days for sleep recovery among nurses.
目的: 比较固定白班和轮值夜班护士的早晚唾液褪黑素水平、睡眠质量和作息类型。 背景: 轮值夜班工作是护理工作中不可避免的,也是影响睡眠的一个重要原因。 设计: 横截面对比研究。 受试者和环境: 我们采用整群抽样方式,在阿联酋招募了520名固定日班和轮值夜班的女护士。 方法: 从相应的唾液样本中测量早晚褪黑素。睡眠质量评估用匹兹堡睡眠质量指数和首选昼夜时间自我评估用于评估受试者的作息类型。数据收集时间为2017年10月至2018年12月。 结果: 与固定白班护士相比,轮值夜班护士的晚间褪黑素显著降低。尽管轮值夜班组受试者(N=110,42.31%)比固定日班组受试者(N=90,36.00)的睡眠质量更好,但组间睡眠质量没有显著差异。与固定日班组受试者相比,轮值夜班组受试者表示主观睡眠质量更好,睡眠时间更长,睡眠干扰更少,日常生活功能更好(P>.05)。与固定日班组受试者相比,轮值夜班组受试者更有可能具有晚间或中间作息类型,更有可能报告轮班工作与他们的作息类型一致(p=.001)。在轮值夜班护士中,晚间褪黑素的减少与较长的轮班时间、婚姻状况和城市位置有关。 结论: 轮值夜班护士的睡眠质量优于固定日班护士的睡眠质量。适当的轮班制度、作息类型以及与轮班工作的一致性似乎能产生更好的睡眠质量。 影响: 组织政策必须考虑一种新的工作时间模式,该模式使得护士有足够的非工作日进行睡眠恢复。.

We assessed salivary melatonin levels in renal transplant (RTx) recipients who participated in a randomised, multicentre wait-list controlled trial on the effect of bright light therapy on their sleep and circadian rhythms. A large proportion of RTx recipients in our cohort had unexpectedly low melatonin values, which precluded calculation of the dim-light melatonin onset (DLMO) as a circadian marker. Thus, the aim of this post hoc analysis was to describe the melatonin profile of home-dwelling RTx recipients diagnosed with sleep-wake disturbances (SWDs). The participants were characterised by means of sleep questionnaires, validated psychometric instruments [Pittsburgh sleep quality Index (PSQI), Epworth sleepiness scale (ESS), Morningness-Eveningness Questionnaire (MEQ) and Depression, Anxiety and Stress Scale (DASS)] in addition to melatonin assay in saliva. Data were analysed with descriptive statistics and group comparisons made with appropriate post hoc tests. RTx recipients [n = 29 (aged 54.83 ± 13.73, transplanted 10.62 ± 6.84 years ago)] were retrospectively grouped into two groups: RTx recipients whose dim light melatonin onset (DLMO) could be calculated (n = 11) and those whose DLMO could not be calculated (n = 18). RTx recipients having a measurable DLMO had a number of differences from those without DLMO: they were younger [46.4 ± 14.9 compared to 60.0 ± 10.3 (p = .007)], had higher haemoglobin values [135.36 ± 12.01 versus 122.82 ± 11.56 (p = .01)], less anxiety [4 (0;8) versus 12 (6.5;14) (p = .021)] and a better overall sense of coherence [SOC Score: 71.09 ± 12.78 versus 56.28 ± 15.48 (p = 0.013)]. These results suggest that RTx recipients whose DLMO could be calculated have less health impairments, underlying the relevance of a stable circadian system.

A decrease in the quality of sleep is believed to cause anxiety and worsen depression. Comparisons of salivary melatonin levels with different factors including quality of sleep, state and trait anxieties, and depression, were conducted to examine whether there is a relationship between melatonin, presumably associated with sleep, and psychological stress. The saliva of healthy young females was collected during the daytime and before they went to bed at night (when they were awake and resting in a sitting position), and salivary melatonin levels were measured. The quality of sleep was scored using the Pittsburgh Sleep Quality Index (PSQI)-a questionnaire method. State and trait anxieties, and depression were scored using other questionnaire methods: the State-Trait Anxiety Inventory (STAI) and Self-Rating Depression Scale (SDS), respectively. The following findings were obtained: (1) Salivary melatonin levels measured during the daytime and before going to bed were higher in females with a high depression score, compared to those with a low score, and there was a correlation between the depression scores and salivary melatonin levels measured at night; and (2) salivary melatonin levels measured before going to bed at night (in a sitting position) were higher in females with a high state anxiety score, suggesting a correlation between state anxiety scores and salivary melatonin levels during the night. Both depression and a sense of anxiety are forms of psychological stress. Therefore, it is assumed that, when a person is under psychological stress, the action of melatonin as a ligand on its receptor is reduced. Meaning psychological stress may induce oxidative stress in the body. On the other hand, no correlation was noted between the quality of sleep and salivary melatonin levels during the night, presumably because saliva was collected when the subjects were awake and sitting, rather than sleeping.

BACKGROUND: Epidemiological studies in Japan have documented an association between morning type and a tryptophan-rich breakfast followed by exposure to sunlight in children. The association may be mediated by enhanced melatonin synthesis, which facilitates sleep at night. However, melatonin is inhibited by artificial light levels with high color-temperature common in Japanese homes at night. In this study, we investigated whether a combination of tryptophan-rich breakfast and light with low color-temperature at night could enhance melatonin secretion and encourage earlier sleep times.
METHODS: The intervention included having breakfast with protein- and vitamin B6 - rich foods and exposure to sunlight after breakfast plus exposure to incandescent light (low temperature light) at night (October-November, 2010). The participants were 94 members of a university soccer club, who were divided into 3 groups for the intervention (G1: no intervention; G2: asked to have protein-rich foods such as fermented soybeans and vitamin B6-rich foods such as bananas at breakfast and sunlight exposure after breakfast; G3: the same contents as G2 and incandescent light exposure at night). Salivary melatonin was measured around 11:00 p.m. on the day before the beginning, a mid-point and on the day before the last day a mid-point and on the last day of the 1 month intervention.
RESULTS: In G3, there was a significantly positive correlation between total hours the participants spent under incandescent light at night and the frequency of feeling sleepy during the last week (p = 0.034). The salivary melatonin concentration of G3 was significantly higher than that of G1 and G2 in combined salivary samplings at the mid-point and on the day before the last day of the 1 month intervention (p = 0.018), whereas no such significant differences were shown on the day just before the start of the intervention (p = 0.63).
CONCLUSIONS: The combined intervention on breakfast, morning sunlight and evening-lighting seems to be effective for students including athletes to keep higher melatonin secretion at night which seems to induce easy onset of the night sleep and higher quality of sleep.