During Antarctic isolation personnel are exposed to extreme photoperiods. A frequent observation is a sleep onset phase delay during winter. It is not known if, as a result, daytime sleeping in the form of naps increases. We sought to assess sleep patterns - with focus on daytime sleeping - and alertness in a Latin American crew overwintering in Argentine Antarctic station Belgrano II. Measurements were collected in 13 males during March, May, July, September and November, and included actigraphy and psychomotor vigilance tasks. Sleep duration significantly decreased during winter. A total of eight participants took at least one weekly nap across all measurement points. During winter, the nap onset was delayed, its duration increased and its efficiency improved. We observed a significant effect of seasonality in the association of evening alertness with sleep onset. Our results replicate previous findings regarding sleep during overwintering in Antarctica, adding the description of the role of napping and the report of a possible modulatory effect of seasonality in the relation between sleep and alertness. Napping should be considered as an important factor in the scheduling of activities of multicultural crews that participate in Antarctica.

Background: Acute Ischemic Stroke (AIS) represents an economic challenge for health systems all over the globe. Changes of neuroactive steroids have been found in different neurological diseases. We have previously demonstrated that old patients with AIS show changes of plasma cortisol and estradiol concentrations, in that increased steroid levels are associated with a deterioration of neurological status and a worse cognitive decline. Objective: The present study assessed in patients with AIS if changes of behavior, Brain-Derived Neurotrophic Factor (BDNF) and Nitrites (NO-2) bear a relationship with the degree of hypercortisolism. Methods: We recruited patients hospitalized within the first 24 hours of AIS. Subjects were divided into two groups, each one composed of 40 control subjects and 40 AIS patients, including men and women. The neurological condition was assessed using the National Institute of Health Stroke Scale (NIHSS) and the cognitive status with the Montreal Cognitive Assessment (MoCA). The emotional status was evaluated using the Montgomery-Asberg Depression Rating Scale (MADRS), whereas the Modified Rankin Scale (MRS) was used to determine the functional condition. BDNF and NO-2 plasma levels were measured by ELISA and the Griess reaction method, respectively. Results: We found that in AIS patients, increased plasma cortisol was negatively correlated with plasma BDNF and NO-2 levels, neurological condition, cognition, functional responses and emotional status, suggesting a relationship between the declines of clinical, behavioral and blood parameters with stress-induced cortisol elevation. Conclusion: Nitrites and BDNF may represent potential biomarkers for cortisol negative effects on the area of cerebral ischemia and penumbra, potentiating ischemic cell damage.

Background. Although melatonin is widely used in Sleep Medicine for its chronobiological action, its potent antioxidant and mitochondrial regulatory effects, as well as its immunomodulatory and anti-inflammatory functions, make it of interest as a cytoprotective agent in several chronic pathologies. These actions are evident at doses higher than those used for sleep disorders. Even at high doses, melatonin’s adverse effects are few, mild, and self-limited or resolve quickly after discontinuation of treatment. Based on its safety profile, we treated melatonin for sleep disorders in the presence of comorbidities with doses ≥ 40 mg daily. Methods. This was a retrospective mixed observational analytical design comprising a retrospective uncontrolled cohort analysis and a cross-sectional study. Eighty-one patients (57 female) with sleep disorders ranging in age from 55 to 98 years (mean 74.4 years) were treated with melatonin 40 to 200 mg daily (mean 72.7 mg) were examined. Fifty-six percent of patients received treatment for more than 4 years. The control group for the cross-sectional analysis included 81 patients over 52 years of age, matched by age and sex and not receiving melatonin but having sleep disorders within the same period. Results. A significant decrease was observed in arterial hypertension, ischemic heart disease and diabetes mellitus after melatonin administration. Analysis of clinical laboratory variables indicated no changes in the treated group versus the untreated group, except for a lower alkaline phosphatase concentration in patients who received melatonin. Conclusions. These findings suggest a beneficial effect of cytoprotective doses of melatonin on the cardiovascular and metabolic profile in an aged population.

The administration of melatonin in chronobiotic doses (≤10 mg daily) is a common procedure in clinics. In addition, research in animals has led to greater awareness on the potentiality of melatonin as an antioxidant, immunological and mitochondrial regulator and anti-inflammatory compound. Doses allometrically derived from animal studies correspond to 75 to 112.5 mg daily range for a 75 kg human adult. In view of the absence of toxicity of melatonin in phase 1 pharmacological studies with doses up to 100 mg in normal volunteers, we regularly use melatonin in this dose range to treat sleep disorders in aged patients to prevent age-related comorbidities. In an observational, analytical, retrospective, cross-sectional study of clinical history data from a closed population of patients taking melatonin in doses equal to or greater than 40 mg/day of melatonin for various sleep disorders, 80 patients (74.2 % female, mean age 74 years ± 9.26) were included. The indication of melatonin doses varied between 40 and 200 mg per day, with a mean of 76.56 mg ± 33.58 mg daily. The main reason for indication was complaints of disorders in falling asleep or maintaining sleep with melatonin doses varying depending on the comorbidities clinically detected. The 59 % of patients received treatment for more than 4 years. Laboratory variables related to liver function remain within the normal range after melatonin administration regardless of the dose employed. No relation was also found between melatonin dose and concomitant pharmacological treatment. The results advocate for the safe use of melatonin in higher doses than those commonly employed.

Introducción: Los trastornos respiratorios durante el sueño (TRDS), sobre todo el síndrome de apneas hipopneas obstructivas (SAHOS) en pacientes con accidente cerebrovascular o ACV, son frecuentes y pueden complicar su evolución. El objetivo fue analizar diversos TRDS en pacientes con ACV. Métodos: Estudio descriptivo, de corte transversal y retrospectivo de 19 meses, en pacientes con ACV, mediante polisomnografía nocturna con oximetría (PSG). Resultados: Se incluyó a 53 pacientes, con edad media de 67 ± 12 años, y 62% pertenecían al sexo masculino. Se evaluó los TRDS mediante polisomnografía nocturna con oximetría dentro de los 10 días de instalado el ACV. Se detectó un índice de apneas hipopneas durante el sueño (IAH) de grado leve en 21%, grado moderado en 31% y severo en 34%. La media de tiempo de saturación de oxígeno < a 90% fue de 38 ±51 minutos. La saturación mínima de oxígeno fue marcada en lesiones infratentoriales. Conclusión: Nosotros hemos encontrado en nuestro estudio, un alto porcentaje de SAHOS, que se asoció a pacientes de mayor edad y mayor índice de masa corporal. Se constató descenso marcado de la saturación mínima y mayor tendencia a presentar apneas centrales en lesiones infratentoriales. El diagnóstico y tratamiento precoz podría minimizar el daño neuronal y mejorar el pronóstico.