Sleep is essential component of life. Even though the research in this field develops constantly, there are still many aspects of this rather complex process that remains to be fully clarified. One of these aspects, reason why we actually sleep, is perhaps the most crucial. In this mini review we aim to address this question and discuss potential functions of sleep. Many recent scientific papers are currently available that covers similar topic. We tried to summarize these recent findings. There are certainly many ways how to approach this rather complex issue. Our article will specifically focus on role of sleep in neuronal development, synaptic plasticity, memory consolidation or mental health in general. Its role in immune system functioning will also be mentioned. Moreover, we will also consider more general functions of sleep, such as well-being of the organisms or securing survival of the individual. In conclusion, we will highlight possible main function of sleep.

• MeSH
• Mental Health * MeSH
• Memory Consolidation MeSH
• Humans MeSH
• Brain immunology   physiology   MeSH
• Neuroimmunomodulation MeSH
• Neuronal Plasticity MeSH
• Sleep * MeSH
• Health Status MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

Recent studies reported association of sleep-disordered breathing (SDB) with testosterone and vitamin D deficiency. Low testosterone and vitamin D levels have been linked to fatigue and excessive daytime sleepiness (EDS). However, the impact of testosterone and vitamin D deficiency on EDS in subjects with SDB remains unknown. The aim of this study was to explore the predictors of EDS in habitual snorers. Role of testosterone, and vitamin D was studied in detail. We also looked for associations between testosterone, vitamin D, and sleep-related indices. We prospectively enrolled 291 consecutive male patients with habitual snoring. Baseline clinical characteristics were recorded on admission. Standard overnight polysomnography was performed to detect SDB, and Epworth Sleepiness Scale (ESS) was used to assess EDS. Blood samples were obtained in a fasting condition in the morning after polysomnography to determine levels of testosterone and vitamin D. Respiratory disturbance index (RDI) (95 % CI: 1.004-1.024, p=0.005) and the use of antihistamines (95 % CI: 1.083-11.901, p=0.037) were the only independent variables significantly associated with EDS in binary logistic regression analysis. In linear multiple regression analysis, body mass index (BMI) (Beta=-0.282, p<0.001) and oxygen desaturation index (Beta=-0.150, p=0.043) were the only independent variables significantly associated with testosterone levels, and BMI (Beta=-0.142, p=0.016) was the only independent variable significantly associated with vitamin D. We failed to find any independent association of testosterone and vitamin D with subjectively rated EDS among habitual snorers. Our results suggest an independent association between the magnitude of nocturnal desaturation and testosterone levels.

• MeSH
• Body Mass Index * MeSH
• Middle Aged MeSH
• Humans MeSH
• Vitamin D Deficiency blood   pathology   MeSH
• Sleep Apnea, Obstructive blood   pathology   MeSH
• Polysomnography methods   MeSH
• Disorders of Excessive Somnolence blood   pathology   MeSH
• Prospective Studies MeSH
• Testosterone blood   MeSH
• Vitamin D blood   MeSH
• Vitamins blood   MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• United Kingdom epidemiology   MeSH
• Names of Substances
• Testosterone MeSH
• Vitamin D MeSH
• Vitamins MeSH

Obesity increases the incidence of hypogonadism in men, and hypogonadism in turn plays a role in obesity. One of the first mechanisms proposed to explain this was a hypothesis based on the principle that obese men have higher estrogen levels, and that increased estrogens provide feedback to the hypothalamic-pituitary-testicular axis, reducing the secretion of gonadotropins and leading to a decrease of overall testosterone levels. This concept has since been questioned, though never completely disproven. In this study we compared hormone levels in three groups of men with differing BMI levels (between 18-25, 25-29, and 30-39), and found correlations between lowering overall testosterone, SHBG and increased BMI. At the same time, there were no significant changes to levels of free androgens, estradiol or the gonadotropins LH and FSH. These findings are in line with the idea that estrogen production in overweight and obese men with BMI up to 39 kg/m(2) does not significantly influence endocrine testicular function.

• MeSH
• Androgens blood   MeSH
• Adult MeSH
• Estradiol blood   MeSH
• Estrogens blood   MeSH
• Follicle Stimulating Hormone blood   MeSH
• Hypogonadism blood   epidemiology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Luteinizing Hormone blood   MeSH
• Young Adult MeSH
• Obesity blood   epidemiology   MeSH
• Aged MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Androgens MeSH
• Estradiol MeSH
• Estrogens MeSH
• Follicle Stimulating Hormone MeSH
• Luteinizing Hormone MeSH