Many systemic functions display circadian rhythms driven by an endogenous mechanism that is regulated by circadian-related genes and these gene expressions control a central clock in the brain and subordinate clocks in peripheral tissues. However, modern life has introduced environmental factors that often interfere with natural circadian rhythms. Importantly, circadian disruption has been identified as an independent risk factor of cancers. Melatonin is a major circadian rhythm regulator. In cancer patients, the rhythm of melatonin is often disrupted and its level is also reduced.  These changes of melatonin impair its antioxidant and circadian regulatory functions on cells and tissues making them more susceptible to mutations and cancer initiation. In this context, the objectives of this study are to evaluate the sleep quality and blood levels of melatonin in patients with either prostate cancer (PC) or hepatocarcinoma (HCC) with the intent of using its levels as a potential biomarker of the cancers. The study involved 20 PC and 18 HCC patients, and 26 healthy volunteers. All blood samples were collected in the early morning, at 07:00 hours. Comparative sleep quality between PC, HCC patients and control subjects was acessed with a questionnaire, and melatonin and vitamin D were measured using conventional assays. The results revealed that patients with the worse sleep quality also had lower values of melatonin and vitamin D compared to control subjects. Notably, expression of melatonin-synthesizing enzymes and specific clock genes (PER, CRY and BMAL1) were significantly reduced and associated with worse prognosis in PC and HCC patients. These findings are consistent with the results of previous studies and suggest that disruption of the circadian rhythms, associated with changes in the light:dark cycle, has consequences for the maintenance of systemic health. We suggest that supplementation of melatonin and vitamin D may represent the important therapeutic strategies for patients with solid tumors for the purpose of improving their sleep quality and recuperative capacity.

Objective: To identify the perceptions of mothers regarding the importance of breastfeeding. A crosssectional study was conducted with a sample of 385 mothers recruited from three locations: a general hospital (n=73), children's hospital (n=227) and the Pro-Infancy Clinic (n=85). Data were collected using a semi-structured questionnaire on breastfeeding. Data analysis considered absolute and relative frequencies. Among the 385 mothers, 9.4% were not counseled regarding the properties and benefits of breast milk. The desire to breastfeed during pregnancy changed in 24.7% mothers after the child was born. The main difficulties during breastfeeding were "nipple pain and injury" (64.7%) and "altered sleep pattern" (63.6%). A total of 32.2% participants had difficulty reconciling breastfeeding and work; 65.5% of mothers introduced artificial milk, juices, teas, water, and cow's milk before six months of age; and 72.5% used pacifier/bottle feeding before six months of age. Difficulties during breastfeeding and the justifications of mothers who do not breastfeed show that simple measures can increase adherence to and the maintenance of breastfeeding. Maternity leave among working women is a favorable measure for the maintenance of exclusive breastfeeding. The assurance of exclusive breastfeeding for a longer time could probably reduce the use of devices such as a pacifier/bottle-feeding and lead to the later introduction of complementary foods, which are the main causes of the discontinuation of breastfeeding.

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