Saliva Melatonin Levels Research Articles

Heat Treatment of Saliva to Reduce Infectious Disease Contamination Does Not Impact the Analysis of Melatonin by Radioimmunoassay.

The determination of melatonin levels in saliva represents one of the key methods for assessing the timing of the central circadian clock in humans, both in research and clinical settings. Melatonin levels in saliva are typically determined in a laboratory setting by RIA or enzyme-linked immunosorbent assay and the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presented a serious challenge to the routine, safe assessment of melatonin in saliva samples. However, SARS-CoV-2 present in biological fluids can be inactivated by exposure to temperatures of at least 55-60°C for 30 min and the aim of this study was to assess the validity of applying a pretreatment heating step to saliva samples being prepared for melatonin determination using the Novolytix Radioimmunoassay (RK-DSM2). 40 archived saliva samples collected under a Dim Light Melatonin Onset sampling protocol were thawed and aliquoted into three identical groups-Controls (no pretreatment), 56°C pre-assay heat-treatment (30 min), and 70°C pre-assay heat-treatment (30 min). Melatonin concentrations in samples that were heated to 56°C for 30 min before assaying showed close agreement with the untreated controls, with the Pearson's correlation coefficient between the two sets of samples of 0.99 (p < 0.0001) and the slope of the Deming regression analysis close to 1.0 (Y = 1.04X + 0.168). When saliva samples were pretreated to 70°C for 30 min before assaying, the subsequent melatonin determinations were still strongly correlated with the untreated controls (Pearsons correlation coefficient = 0.97 (p < 0.0001), however melatonin concentrations were consistently overestimated when compared to the untreated controls with Deming regression slope of Y = 1.26X + 0.241. These results indicate that a 56°C pretreatment step is suitable for inclusion in standard operating protocols for melatonin determinations using the Novolytix RIA, as a way of effectively minimizing the potential for accidental pathogen exposure while handling saliva samples.

Effect of Non-surgical Periodontal Therapy on Salivary Melatonin Levels

Objective: Melatonin, a hormone secreted predominantly by pineal gland in a circadian manner, has antioxidant and anti-inflammatory effects. The current research is conducted to explore the influence of non-surgical periodontal therapy (NSPT) on levels of salivary melatonin in subjects with gingivitis and periodontitis. Methods: Sixty systemically healthy participants were included in this study; the groups are as follows: gingivitis (G), chronic periodontitis (CP), generalized aggressive periodontitis (GAP) and periodontally healthy (H). NSPT was applied to G group patients for 2 sessions, to CP and GAP group patients for 4 sessions. Plaque and gingival indices, probing depth (PD), bleeding on probing (BOP), and clinical attachment level (CAL) were documented at baseline and 3 months post – treatment and early morning salivary samples were collected. ELISA was used to detect melatonin levels in saliva. Pittsburgh Sleep Quality Index (PSQI) questionnaire was performed to evaluate of sleep quality of patients. Results: At baseline, significant difference in gingival index, PD, BOP and CAL values was detected among all groups (p

Comparison of melatonin levels in saliva in individuals with healthy periodontium, generalized chronic gingivitis and generalized chronic periodontitis

Introduction: Melatonin, is a hormone secreted by the pineal gland which activates several elements of the immune system that reduce tissue destruction during the inflammatory response, either directly by scavenging free radical, reactive oxygen species and reactive nitrogen species or indirectly by modulating the action of agents such as cytokines and adhesion molecules, which contribute to the advance of cell damage. Aim: The aim of the present study was to compare and evaluate melatonin levels in saliva in individuals with healthy periodontium, generalized chronic gingivitis and generalized chronic periodontitis. Materials and method: A total of 60 patients were examined and assessed and divided into 3 groups; Group 1: 20 individuals with healthy periodontium, Group 2: 20 individuals with generalised chronic gingivitis and Group 3: 20 individuals with generalised chronic periodontitis. Saliva samples were collected from each sample and melatonin levels were assessed using ELISA, a competitive immunoassay using a capture antibody technique. Results: Melatonin levels in saliva was highest in individuals with healthy periodontium when compared to gingivitis and periodontitis group which was highly significant and inversely proportional correlation was observed between periodontal index and melatonin levels which was statically significant.

Melatonin relieves Th17/CD4−CD8− T cells inflammatory responses via nuclear-receptor dependent manner in peripheral blood of primary Sjögren’s syndrome

ObjectivesPrimary Sjögren’s syndrome (pSS) is a complex systemic autoimmune disease whose clinical spectrum extends from sicca syndrome to systemic involvement. T helper 17 cells (Th17) and CD4−CD8− (double negative, DN) T cells are actively involved in the pathogenesis of pSS. Melatonin shows important immunoregulatory functions in multiple T cell-mediated autoimmune diseases. However, the effects of melatonin on the immune cells of pSS patients are unclear. Hence, this study was aimed to evaluate the effects of melatonin on the immune responses of peripheral pathogenic Th17 and DN T cells from pSS patients, and explore the underlying receptor-related mechanism. MethodsThe concentration of serum and saliva melatonin of pSS patients and healthy controls (HCs) were detected using Enzyme-linked immunosorbent assays (ELISA). Expression of arylalkylamine N-acetyltransferase (AANAT) and hydroxyindole O-methyltransferase (HIOMT) were conducted in labial glands samples by immunohistochemistry. The mechanism underlying the effects of melatonin on Th17 and DN T cells responses in peripheral blood from pSS was investigated by quantitative real-time polymerase chain reaction (RT-PCR), flow cytometry, ELISA, cell viability, and proliferation assays. ResultsSerum and saliva melatonin levels were lower in pSS patients than in HCs, which were negatively correlated with disease activity. The expression levels of melatonin's biosynthetic enzymes (AANAT, HIOMT) and nuclear receptors (RORα, RORγ) were significantly increased in peripheral blood mononuclear cells (PBMCs) from pSS patients. Furthermore, in vitro melatonin administration decreased the expression of melatonin effector/receptor system in peripheral blood of pSS patients. More importantly, Melatonin inhibited pathogenic responses of peripheral Th17 and DN T cells in PBMCs from pSS, which was independent of melatonin membrane receptors. However, melatonin nuclear receptor antagonist SR1001 enhanced the inhibitory ability of melatonin on Th17 and DN T cells production, and agonist SR1078 weakened the effects of melatonin. Additionally, overexpression of the melatonin effector/receptor system in pSS patients appeared to be involved in the disease, due to that melatonin effector/receptor system expression was correlated with the frequency of Th17 or DN T cells. ConclusionMelatonin relieved the inflammatory responses of Th17 and DN T cells in PBMCs from pSS patients in a nuclear receptors-dependent manner,suggesting that melatonin might be beneficial to pSS.

Melatonin in the saliva of adolescent girls with polycystic ovary syndrome

Background. The formation of polycystic ovary syndrome (PCOS) and the manifestation of its clinical manifestations often begin in adolescence. In recent years, one of the new and modern areas in the study of reproductive dysfunction is the problem of melatonin on the gonadotropic function of the pituitary gland (ovariogenesis). The purpose of the study was to determine the level of melatonin in the saliva of adolescent girls with PCOS. Materials and methods. A single-center prospective simple randomized study was conducted with 23 patients aged 14–18 years (inclusive) with PCOS. The control group consisted of 25 girls of the same age without gynecological status violations. Determination of melatonin levels in saliva was performed by high performance liquid chromatography with tandem mass spectrometry (HPLC-MS). Before salivation during the day and throughout the saliva collection period, patients excluded caffeine, alcohol, and exercise, did not smoke for one hour before collection, did not brush their teeth, did not floss, rinsed their mouths, and did not chew gum. Results. There were no significant differences in the age of the girls in the main group and the comparison group (16.70±0.11 years in the main group and 16.90±0.14 years in the comparison group, p&gt;0.05). The most common symptoms of PCOS in girls were: hypomenstrual syndrome (86.9%), dermopathy (82.6%) and hirsutism (60.8%). Girls with PCOS had significantly higher melatonin levels in saliva (03:00) (28.89 [18.17; 46.53] pg/ml) compared to girls in the comparison group (12.07 [11.56; 16.27] pg/ml, p&lt;0.01). A probable difference in melatonin levels in saliva depending on age has not been established. Conclusions. The results of the study indicate a violation of hormonal balance in polycystic ovary syndrome, in particular an increase in melatonin levels, which indicates the need to determine it in the process of diagnosis and treatment.

The relationshipof the quality of sleep in patients with stage 5 chronickidney disease, treated with hemodialysis, with melatonin-producing function

The researcheddemonstrated the relationship between functional state of the pineal gland and sleepdeterioration. However, impaired melatonin-producing function of the pineal gland (MFE) in patients with chronic kidney disease (CKD), treated with hemodialysis (HD), and its association with sleep disturbance in this cohort of patients required further investigations.Aim — to assess the quality of sleepin patients with stage 5 CKD treated with HD and investigate itsrelationship with the pineal dysfunction.Materials and methods. Examinations involved 130 patients (50 % of men) with stage 5 CKD, treated with hemodialysis, with the mean age 58.5 [43; 66]. The day and night melatoninlevels (MT) in saliva were determined and based on the results the patients were divided into two groups: group I — 110 patients with impaired MFE, group II — 20 patients with normal MFE. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) questionnaire. All patients underwent clinical and laboratory tests: general and biochemical blood tests, office blood pressure (BP) measurements, Holter blood pressure monitoring.Results. Analysis of the insomniastructure in patients with stage 5 CKD, treated with HD, according to the PSQI questionnaire, demonstrated the problems with falling asleep in 96.2 % of patients, feeling of heat in 56.8 %, frequent awakenings in 52.9 %, daytime dysfunction in 40.8 %, breathing problems in 40.5 %, sleep problems due to coughing or snoring in 37.8 %, having bad dreams in 18.9 %, the use of sleeping meds in 8 % of patients. The total PSQI score in patients with impaired MFE was higher by 71.4 % (p &lt; 0.001) compared to the value obtained in the group with preserved pineal gland function, demonstrating the effects of MFE on sleep quality.The component of «sleep delay» and «sleep duration» in patients with pineal gland dysfunction was 66.7 % higher than in the group with preserved MFE (p &lt; 0.001). Comparative analysis of the number of minutes required for patients to fall asleep in the study groups demonstrateda greater sleep delay in HD-treated patients with impaired MFE. From them, the majority of subjects (71.8 %) needed more than 60 minutes to fall asleep, while in the group with preserved MFE such patients were not identified (p &lt; 0.05). The number of patients with the period of falling asleep of 31 to 60 minutes in the group with pineal gland dysfunction was 30 % less than in patients with preserved MFE (p &lt; 0.05). The number of patients in whom it took 16—30 minutes to fall asleep in the group with preserved MFE was 92.5 % (p &lt; 0.05) more than in patients with pineal gland dysfunction, and patientswith the period of falling asleep of less than 15 minutes was by 62 % higher than patients with impaired MFE (p &lt; 0.05). The decreased sleep duration was established in all patients treated with HD, however the most worsening of the sleep quality was revealed in the groupof MFE disorders. Thus, thenumber of patients with sleep duration &lt; 5 hourswas by 90.8 % (р &lt; 0.05) higher in the groupof impairedMFEvs group with the preserved MFE, with sleep duration of 5—6 hours by 81.7 % (р &lt; 0.05), the number of subjects with duration of 6—7 hours by 76.4 % lower (р &lt; 0.05), and those who slept &gt; 7 hours by 84.0 % (р &lt; 0.05).Conclusions. Patients with stage 5 CKD, treated with HD, were characterized with combination of MFE impairment (84.6 %) with poor sleep quality (86.2 %), including problems withfalling asleep, felling hot, frequent waking up, and daytime dysfunction. The low quality of sleep was determined bylow melatonin levels in saliva, the presence of hypoalbuminemia and arterial hypertension, hypertension duration and HDtreatment

Brain Tumours Involving the Areas of the Circadian System Result in Disturbances in Melatonin Secretion, Fatigue and Poor Quality of Life

Background: Sleep disturbances, circadian abnormalities and poor health are often reported in children with brain tumours. The objective of this study was to examine circadian function, sleep pattern, fatigue and mental health in these children. We hypothesized that children with tumours involving the areas of the circadian system have altered melatonin secretion. Design: Cross-sectional study. Methods: 309 children diagnosed with a tumour in the brain or cervical medulla and aged ≤18 years were identified, 174 met the inclusion criteria, and 68 consented to participate. They were divided according to their tumour location into 1) location involving the areas of the circadian system, i.e. diencephalon, pineal gland, brain stem and cervical medulla and 2) other areas. Sleep-wake patterns were assessed by two weeks of sleep diary recordings and actigraphy in 66 and 61 children, respectively. Diurnal saliva-melatonin levels were measured in 51 children. Sleep quality, fatigue and mental health were assessed in 65 children by Children’s Sleep Habits Questionnaire, Strengths and Difficulties Questionnaire and Pediatric Quality of Life Inventory, Multidimensional Fatigue Scale and Generic Core Scale. Results: All children had normal sleep-wake patterns without significant between-group differences. The children with tumours involving the areas of the circadian system had lower melatonin peak levels (p=0.03) and a tendency of lower levels at 00 h and 04 h (all p=0.06). Three patterns of diurnal melatonin profiles were observed: Normal, low peak and phase-shifted peak. In comparison of the two patient groups, more children with tumours involving the areas of the circadian system had melatonin profiles with low peak values (29% vs 13%) and one had phase-shifted peak (3% vs 0%), although not significant. These children were more affected by mental problems (p<0.01), more cognitive fatigued (p=0.03) and had poorer quality of life (p=0.01) than children with tumours located elsewhere. Conclusion: Children with tumours affecting the areas of the circadian system including the diencephalon, pineal gland, brain stem and cervical medulla have altered melatonin secretion, are fatigued, have poor mental health and poor quality of life. Circadian disturbances may adversely affect health and have negative psychological impact.

Prospective pilot study to explore the melatonin level in brain tumor patients undergoing radiotherapy.

Our aim was to assess if the radiotherapy dose decreased the melatonin levels as well as the quality of life and sleep in brain tumor patients. We performed a follow-up study on melatonin levels in saliva and its urinary metabolite sulfatoxi-melatonine (STM) samples in patients with brain tumors treated with radiotherapy close to the pineal gland's area. We analyzed the cortisol, cortisone, and excrection of STM normalized by urinary creatinine. In some cases, a polysomnography (PSG) was performed. Quality of life questionnaires, distress scale, and sleepiness inventories were also administered. We included twelve patients (experimental arm) and eight healthy controls (control group). No differences were observed between experimental arm and control group at baseline. No differences were detected in the experimental arm before and after delivering the radiotherapy. No clinically significant differences were found according to the radiotherapy dose delivered. Melatonin levels and PSG outcomes do not change after receiving radiotherapy. The findings of this study do not showa statistically significant association between the treatment and the quality of life and sleep.

Circadian Melatonin Secretion In Obese Adolescents With Or Without Obstructive Sleep Apnea

Objective — To compare melatonin levels in saliva during a 24-hr day in order to identify the specificities of circadian melatonin secretion in obese adolescents with or without obstructive sleep apnea (OSA). Material and Methods — We examined 18 obese adolescents with OSA, 12 obese adolescents without OSA, and 15 healthy adolescents with a normal body weight, from whom saliva was sampled four time during the 24-hr day. Polysomnography was used to diagnose OSA. Saliva samples (n=180) were subjected to enzyme-linked immunosorbent assay. Results — Obese adolescents with OSA had higher evening melatonin levels than obese adolescents without OSA. For example, this indicator in OSA patients was 5.3 times higher than in participants without OSA, who had the lowest evening melatonin level among all groups. In both obese groups, nighttime melatonin levels were significantly lower than in the control group. A positive correlation was detected between the levels of morning and afternoon melatonin and body mass index only in obese adolescents without OSA (r=0.58; p=0.03 and r=0.68; p=0.01, respectively). It was found that evening melatonin correlated with minimum blood oxygen saturation (SaO2) in the entire sample of adolescents with OSA (r=-0.69; p=0.008), and it also correlated with time with SaO2 &lt;90% in the group with clinical manifestations of OSA (r=0.76; p=0.003). Nighttime melatonin levels negatively correlated with the minimum SaO2 value solely in the group with clinical manifestations of OSA (r=-0.58; p=0.035). Conclusion — The circadian melatonin secretion in obese adolescents differed, depending on the presence or absence of OSA, and correlated with the level of oxygen desaturation in OSA patients, to a greater extent – in the presence of clinical manifestations.

Daytime melatonin levels in saliva are associated with inflammatory markers and anxiety disorders

BackgroundThe bidirectional interaction between melatonin and the immune system has largely gone unexplored in a clinical context and especially in a psychiatric population. This study explored the association between melatonin during the day and inflammatory cytokines in young adult patients seeking psychiatric care. MethodsSamples and data were collected from 108 young adults (mean age 21, SD = 2) at an outpatient clinic for affective disorders. Daytime saliva melatonin levels were analyzed with enzyme-linked immunosorbent assay (ELISA) in relation to normalized serum expression levels of 72 inflammatory markers in a proximity extension assay (PEA). In a post hoc analysis the markers associated with melatonin were tested in a generalized linear model to see whether there is a relationship to anxiety disorder or depression. ResultsAfter Bonferroni correction for multiple testing, melatonin levels at 11:00 were positively correlated with CD5 (p = 4.2e-4). Melatonin levels after lunch were correlated with CCL2/MCP-1 (p = 4.2e-4), CCL3/MPI-1α (p = 6.5e-4) and VEGF-A (p = 5.3e-6). In the generalized linear model, positive associations were found for the presence of any anxiety disorder with melatonin after lunch (p = 0.046), VEGF-A (p = 0.001) and CCL3/MPI-1α (p = 0.001). ConclusionDaytime saliva levels of melatonin were related to several inflammatory markers in young adults with psychiatric disorders. This observation likely reflects the bidirectional relationship between melatonin production and the immune system. These findings may have relevance for the understanding of psychiatric disorders and other conditions associated with low-grade inflammation.

The Relationship Between Daytime Salivary Melatonin and Gastrointestinal Symptoms in Young Adults Seeking Psychiatric Care.

The pathophysiology of irritable bowel syndrome (IBS) is not completely understood, although we do know that patients with IBS have a high prevalence of psychiatric comorbidity (mainly depression and anxiety disorders). Melatonin, produced in the gastrointestinal tract, influences gut motility. Psychiatric conditions are associated with circadian disturbances in peripheral melatonin levels. This study aimed to investigate associations between daytime salivary melatonin and gastrointestinal symptoms in young adult psychiatric patients. Ninety-six patients (86% women), aged 18-25 years (M (SD) = 21 (2)), seeking psychiatric care with primarily anxiety disorders, affective disorders, or both were included in the study. Total scores from the Gastrointestinal Symptoms Rating Scale - IBS were compared with salivary melatonin measured at three time points (30 minutes after waking up, at 11:00 hours and 30 minutes after lunch) during the waking hours of 1 day. After adjustment for potential confounders, melatonin levels in saliva 30 minutes after lunch remained significantly correlated to the total Gastrointestinal Symptoms Rating Scale - IBS score after correction for multiple testing (B = 0.016, SE = 0.006, p = .015, q = 0.045). In a post hoc analysis, symptoms of gastrointestinal pain and bloating contributed most to this association. In young adult psychiatric patients, salivary melatonin levels after lunch are associated with gastrointestinal symptoms, which is consistent with the proposed effect of elevated levels of gastrointestinal melatonin on gut motility. This result suggests a link between IBS symptoms and regulation of melatonin in patients with psychiatric disorders.

The role of melatonin and cortisol circadian rhythms in the pathogenesis of infantile colic

Despite the high prevalence of infantile colic, the pathogenesis remains incompletely understood. Cortisol and melatonin hormones affect gastrointestinal system development in several ways, and interestingly, both cortisol and melatonin's circadian rhythms begin around the 3rd month in which infantile colic symptoms start to decrease. We hypothesized that infantile colic might associate with desynchronization of normal circadian rhythms of these hormones. In this study, we aimed to investigate the role of melatonin and cortisol in the pathogenesis of infantile colic. Patients who were diagnosed as infantile colic according to Wessel's "rule of three" were enrolled in the colic group. We measured the saliva melatonin and cortisol levels of colic group and control group infants. In both groups, the saliva samples were taken in mornings and at evenings, at the time of diagnosis and 6th month. Fifty-five infants finished the study. Melatonin circadian rhythm developed earlier in the control group than the infantile colic group in our study. We found no significant difference between the daily mean cortisol levels. However, infants with colic had flatter daily cortisol slope than controls which pointed out the probability that they had a less clearly defined cortisol rhythm than infants without colic. We found an association between melatonin levels and infantile colic. However, more research is needed to fully understand the role of hypothalamic-pituitary-adrenalaxis and hormone's role on infantile colic physiopathology.

Melatonin Secretion during a Short Nap Fosters Subsequent Feedback Learning.

Sleep helps to protect and renew hippocampus-dependent declarative learning. Less is known about forms of learning that mainly engage the dopaminergic reward system. Animal studies showed that exogenous melatonin modulates the responses of the dopaminergic reward system and acts as a neuroprotectant promoting memory. In humans, melatonin is mainly secreted in darkness during evening hours supporting sleep. In this study, we investigate the effects of a short period of daytime sleep (nap) and endogenous melatonin on reward learning. Twenty-seven healthy, adult students took part in an experiment, either taking a 90-min afternoon nap or watching videos (within-subject design). Before and after the sleep vs. wake interval, saliva melatonin levels and reward learning were measured, and in the nap condition, a polysomnogram was obtained. Reward learning was assessed using a two-alternative probabilistic reinforcement-learning task. Sleep itself and subjective arousal or valence had no significant effects on reward learning. However, this study showed for the first time that an afternoon nap can elicit a small but significant melatonin response in about 41% of the participants and that the magnitude of the melatonin response predicts subsequent reward learning. Only in melatonin responders did a short nap improve reward learning. The difference between melatonin-responders and non-responders occurred very early during learning indicating that melatonin might have improved working memory rather than reward learning. Future studies should use paradigms differentiating working memory and reward learning to clarify which aspect of human feedback learning might profit from melatonin.

Analysis of the informativeness of melatonin evaluation in polycystic ovary syndrome

Background. Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women of reproductive age. Recently, the role of melatonin in the pathogenesis of this syndrome became widely discussed among the scientists, because there is an evidence of its impact on the reproductive function and maturation of oocytes.Aim. To study a informativeness of melatonin determination and its relationship with sleep disorders in PCOS.Materials and methods. The study involved 120 women aged 17–35 years: 60 patients with PCOS and 60 women without this disorder as controls. The level of melatonin in the blood, saliva and its metabolite in urine – 6 sulfatoximelatonin were analyzed. To identify sleep disorders survey was conducted using a questionnaire scoring subjective sleep characteristics.Results. Sleep disorders based on subjective scoring profiles sleep characteristics were identified in PCOS group (up to 70% of patients) regardless of BMI. The level of 6-sulfatoximelatonin in urine, nocturnal melatonin levels in saliva (at 3:00 AM) and melatonin in the blood were significantly higher in patients with PCOS compared with the control group regardless of BMI. The level of melatonin in follicular fluid was lower in patients with PCOS. There was a significant correlation of melatonin levels in the blood and the degree of sleep disorders according to the questionnaire scoring subjective sleep characteristics, the level of melatonin in saliva at 3:00 AM and a 6-sulfatoximelatonin in daily urine (p = 0.046).Conclusions. PCOS is polyetiology disease, and an important role in the formation and progression in which plays melatonin. Correlation of levels of this hormone in different body fluids suggests its systemic action and direct involvement in the regulation of reproductive function.

Two hours of evening reading on a self-luminous tablet vs. reading a physical book does not alter sleep after daytime bright light exposure

BackgroundThe use of electronic devices emitting blue light during evening hours has been associated with sleep disturbances in humans, possibly due to the blue light-mediated suppression of the sleep-promoting hormone melatonin. However, experimental results have been mixed. The present study therefore sought to investigate if reading on a self-luminous tablet during evening hours would alter sleepiness, melatonin secretion, nocturnal sleep, as well as electroencephalographic power spectral density during early slow-wave sleep. MethodsFollowing a constant bright light exposure over 6.5 hours (~569 lux), 14 participants (six females) read a novel either on a tablet or as physical book for two hours (21:00–23:00). Evening concentrations of saliva melatonin were repeatedly measured. Sleep (23:15–07:15) was recorded by polysomnography. Sleepiness was assessed before and after nocturnal sleep. About one week later, experiments were repeated; participants who had read the novel on a tablet in the first experimental session continued reading the same novel in the physical book, and vice versa. ResultsThere were no differences in sleep parameters and pre-sleep saliva melatonin levels between the tablet reading and physical book reading conditions. ConclusionsBright light exposure during daytime has previously been shown to abolish the inhibitory effects of evening light stimulus on melatonin secretion. Our results could therefore suggest that exposure to bright light during the day – as in the present study – may help combat sleep disturbances associated with the evening use of electronic devices emitting blue light. However, this needs to be validated by future studies with larger sample populations.

Peripheral Skin Temperature and Circadian Biological Clock in Shift Nurses after a Day off.

The circadian biological clock is essentially based on the light/dark cycle. Some people working with shift schedules cannot adjust their sleep/wake cycle to the light/dark cycle, and this may result in alterations of the circadian biological clock. This study explored the circadian biological clock of shift and daytime nurses using non-invasive methods. Peripheral skin temperature, cortisol and melatonin levels in saliva, and Per2 expression in pubic hair follicle cells were investigated for 24 h after a day off. Significant differences were observed in peripheral skin temperature and cortisol levels between shift and daytime nurses. No differences in melatonin levels were obtained. Per2 maximum values were significantly different between the two groups. Shift nurses exhibited lower circadian variations compared to daytime nurses, and this may indicate an adjustment of the circadian biological clock to continuous shift schedules. Non-invasive procedures, such as peripheral skin temperature measurement, determination of cortisol and melatonin in saliva, and analysis of clock genes in hair follicle cells, may be effective approaches to extensively study the circadian clock in shift workers.

Evaluation of melatonin levels in saliva in gingivitis and periodontitis cases: A pilot study.

Objective:To evaluate the melatonin levels in saliva in gingivitis and periodontitis cases.Background:Melatonin has strong antioxidant, free radical scavenging, and immunomodulating properties, acts on osteoblasts directly to stimulate cell proliferation and synthesis of Type I collagen, and promotes bone formation.Materials and Methods:A total of thirty participants were selected and divided into three groups (control group, gingivitis group, and periodontitis group). In each group, ten participants were taken. Salivary melatonin was estimated in each of the three groups.Results:Results from this study showed that the mean levels of salivary melatonin increased as severity increased from control to periodontitis, i.e., the mean levels were highest in periodontitis followed by gingivitis and least in control group. The melatonin level of all participants was positively and significantly (P < 0.01) correlated with their gingival index (r = 0.85, P < 0.01) and probing depth (r = 0.72, P < 0.01).Conclusion:Salivary melatonin level varied with the severity of gingivitis and periodontitis. With increased severity of periodontal disease, the level of salivary melatonin also increased suggesting that salivary melatonin may act as a diagnostic biomarker for periodontal diseases.

Gingival, plasma and salivary levels of melatonin in periodontally healthy individuals and chronic periodontitis patients: a pilot study.

Periodontal disease is an inflammatory condition affecting tooth supporting structures in which dysregulated immune response and oxidative stress mediate tissue destruction. Melatonin, the pineal gland hormone is a regulator of circadian rhythm, an antioxidant and an immunomodulator. Previous studies have shown lowered melatonin levels in saliva, plasma and gingival crevicular fluid (GCF) of patients with periodontal disease. Till date no study has assessed the melatonin levels in gingival tissues. Five healthy individuals and 15 chronic periodontitis patients were recruited for this pilot study. 5ml of whole saliva, 2 ml peripheral blood and gingival tissue samples were obtained from each individual at 8.00 am in fasting state. Melatonin assay was performed with a commercially available ELISA kit. Statistical analysis was done to assess the difference in mean melatonin levels among the groups. No statistically significant difference was found in mean melatonin levels between healthy individuals and chronic periodontitis patients in saliva (p=.266) and plasma (p=.933) samples, whereas in gingival tissue samples (p=.015), the melatonin levels were significantly lowered in chronic periodontitis patients compared to healthy individuals. This study demonstrates the presence of melatonin in gingival tissue. Furthermore, melatonin levels are lowered in gingival tissues of chronic periodontitis patients.

The circadian system of patients with bipolar disorder differs in episodes of mania and depression.

Bipolar disorder is a common psychiatric disease characterized by mood disturbances with alternating episodes of mania and depression. Moreover, disturbances in the sleep/wake cycle are prevalent. We tested a hypothesis that the function of the circadian system, which drives the sleep/wake cycle, may differ in patients with bipolar disorder depending on whether they are experiencing an episode of mania or depression. To assess the functional state of the central circadian clock, daily profiles of melatonin levels in saliva were determined. The functional state of the peripheral clocks was assessed by determining daily profiles of Per1 and Nr1d1 clock gene expression in buccal mucosa cells. Sixteen patients with bipolar disorder in a manic episode, 22 patients in a depressive episode, and 19 healthy control subjects provided samples at regular intervals during a 24-hour cycle. During episodes of mania, the daily profiles of melatonin differed compared with healthy controls and patients in an episode of depression, mainly due to elevated melatonin levels during the daytime. No difference was found between melatonin profiles of control subjects and patients in depression. The Per1 and Nr1d1 profiles were advanced in patients in mania compared with those in depression. Compared with controls, a trend toward an advance was apparent in the profiles of patients during an episode of mania but not depression. The amplitude of the Nr1d1 expression profile was higher in mania than in depression. The data revealed differences in the functional state of the circadian system in patients with bipolar disorder depending on whether they were experiencing a manic or a depressive episode.

Optimal dosages for melatonin supplementation therapy in older adults: a systematic review of current literature.

Melatonin is a hormone that regulates circadian rhythm, and its levels decline with age. As melatonin levels decrease, older adults are prone to develop disorders related to an altered circadian rhythm. The effective dose of melatonin supplementation in these disorders remains unclear. Our objective was to define the optimal dosage of exogenous melatonin administration in disorders related to altered melatonin levels in older adults aged 55years and above by determining the dose-response effect of exogenous administered melatonin on endogenous levels. We conducted a systematic review through PubMed/MEDLINE and Embase, both from 1980 until November 2013. Included articles studied the effect of exogenous melatonin administration on endogenous melatonin levels in either serum, urine, or saliva in humans aged 55years and above. We included 16 articles, nine of which were randomized controlled trials (RCTs). The mean age varied from 55.3 to 77.6years. Melatonin dosage varied from 0.1mg to 50mg/kg and was administered orally in all studies. Pre- and post-intervention levels revealed a significant elevation of the post-intervention melatonin levels in a dose-dependent fashion. The maximum concentrations measured in serum and urine were all elevated compared with placebo, and a higher elevation in older adults than in younger adults was demonstrated. Even though there were no differences between times to reach maximum concentration in serum and urine, melatonin levels with higher doses were maintained longer above a certain threshold than were lower doses. In older adults, we advise the use of the lowest possible dose of immediate-release formulation melatonin to best mimic the normal physiological circadian rhythm of melatonin and to avoid prolonged, supra-physiological blood levels.