[Disturbances in melatonin secretion and the efficacy of replacement therapy in sleep disorders]

Sex differences in the effects of sleep disorders on cognitive dysfunction

Sleep is an essential physiological function that sustains human life. Sleep disorders involve problems with the quality, duration, and abnormal behaviour of sleep. Insomnia is the most common sleep disorder, followed by sleep-disordered breathing (SDB). Sleep disorders often occur along with medical conditions or other mental health conditions. Of particular interest to researchers is the role of sleep disorders in cognitive dysfunction. Sleep disorder is a risk factor for cognitive dysfunction, yet the exact pathogenesis is still far from agreement. Little is known about how sex differences influence the changes in cognitive functions caused by sleep disorders. This narrative review examines how sleep disorders might affect cognitive impairment, and then explores the sex-specific consequences of sleep disorders as a risk factor for dementia and the potential underlying mechanisms. Some insights on the direction of further research are also presented.

Melatonin and its Relationships with Diabetes and Obesity: A Literature Review

BACKGROUND

Obesity is an important clinical entity, causing many public health issues. Around two billion people in the world are overweight and obese. Almost 40% of American adults are obese and Brazil has about 18 million obese people. Nowadays, 415 million people have diabetes, around 1 in every 11 adults. These numbers will rise to 650 million people within 20 years. Melatonin shows a positive profile on the regulation of the metabolism of the human body.

OBJECTIVE

This study aimed to carry out a broad narrative review of the metabolic profile and associations between melatonin, diabetes and obesity.

METHODS

Article reviews, systematic reviews, prospective studies, retrospective studies, randomized, double-blind, and placebo-controlled trials in humans recently published were selected and analyzed. A total of 368 articles were collated and submitted to the eligibility analysis. Subsequently, 215 studies were selected to compose the content part of the paper, and 153 studies composed the narrative review.

RESULTS

Studies suggest a possible role of melatonin in metabolic diseases such as obesity, T2DM and metabolic syndrome. Intervention studies using this hormone in metabolic diseases are still unclear regarding the possible benefit of it. There is so far no consensus about the possible role of melatonin as an adjuvant in the treatment of metabolic diseases. More studies are necessary to define possible risks and benefits of melatonin as a therapeutic agent.

[The role of melatonin as a component of the antioxidant defense system in perimenopausal women with insomnia]

AIM

To determine the ethnic features of the functioning of the 'lipid peroxidation-antioxidants' system and to evaluate the role of melatonin as one of the antioxidant defense system components in Caucasian and Asian perimenopausal women with insomnia.

MATERIAL AND METHODS

One hundred and ten perimenopausal women divided into Caucasian (Russian ethnic group (n=60)) and Asian (Buryat ethnic group (n=50)) were studied. All women underwent clinical-anamnestic examination. Diagnoses of insomnia and obstructive sleep apnea syndrome (OSAS) were made according to the results of specialized somnological questionnaires and polysomnographic monitoring. A multidimensional discriminant analysis was used to reveal the most informative parameters among the hormonal and metabolic parameters studied (melatonin 06.00-07.00h; 12.00-13.00h; 18.00-19.00h; 23.00-00.00h; lipid profile, lipid peroxidation and antioxidant defense system).

RESULTS

The most informative indicators of the metabolic system in Caucasians with insomnia are morning, evening, night melatonin, ketodienes and conjugated trienes, oxidized glutathione (GSSG); with insomnia and OSAS: morning, day, night melatonin, substrates with conjugated double bonds, total cholesterol; in Asian women with insomnia: evening, night melatonin, superoxide dismutase activity (SOD), diene conjugates, active products of thiobarbituric acid, cholesterol of very low density lipoproteins; in women with insomnia and OSAS: morning, day melatonin, SOD, GSSG. The recalculation of the informativeness of each attribute as a percentage showed the prevalence of the influence of the antioxidant protection system parameters over those of lipid peroxidation processes. The contribution of melatonin to the total share of the antioxidant protection system components is more than 60%.

CONCLUSION

Both in Caucasian and Asian women with sleep disorders, there is stress in the antioxidant defense system, where melatonin is the largest contributor.