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.

RESUMENLa atención conjunta, definida como la coordinación visual de dos individuos dirigida hacia un objeto de interés mutuo, es una habilidad nuclear que se desarrolla durante la infancia temprana y es la base de la futura capacidad lingüística, emocional, de la teoria de la mente y de la cognición en general de toda persona. Este fenómeno incluye la adquisición de comportamientos como el seguimiento de mirada y señalamiento. Por otro lado, la vulnerabilidad social es un factor de riesgo estudiado en relación con numerosas variables como la memoria, las funciones ejecutivas y distintas patologías. En este caso, se propone investigar la modulación que ejerce la vulnerabilidad social sobre las habilidades de seguimiento de mirada y señalamiento en la primera infancia. La muestra estuvo conformada por 18 infantes entre 9 a 13 meses. Se midieron las conductas de comunicación a partir del seguimiento de la mirada y del señalamiento del infante a objetos distantes señalizados por el evaluador. Se midió la latencia y duración de la conducta de seguimiento a través del análisis conductual aplicado. La vulneravilidad social fue medida utilizando la Escala de Nivel Económico Social (NES). Los resultados reflejan que no se encuentran diferencias en las capacidades de seguimiento de la mirada y señalamiento según el nivel socioeconómico. Estos resultados resaltan que a pesar de que el nivel socioeconómico produce limitaciones en las habilidades comunicativas, no habría aún efectos visibles en los primeros estadios del desarrollo. ABSTRACT Joint attention, defined as the visual co-ordination of two individuals directed towards an object of mutual interest, is a nuclear skill that develops during early childhood and is the basis of the future linguistic, emotional capacity of mind theory and Of the general cognition of every person. This phenomenon includes the acquisition of behaviors such as the tracking of gaze and signaling. On the other hand, social vulnerability is a risk factor studied in relation to many variables such as memory, executive functions and different pathologies. In this case, it is proposed to investigate the modulation that social vulnerability exerts on the abilities of followup of gaze and signaling in early childhood. The sample consisted of 18 infants between 9 and 13 months. Communication behaviors were measured from the follow-up of the gaze and from the infant's pointing to distant objects marked by the evaluator. The latency and duration of follow-up behavior were measured through applied behavioral analysis. Social vulnerability was measured using the Social Economic Level Scale (NES) (INDEC, 2000). The results reflect that there are no differences in the abilities to follow the look and pointing according to the socioeconomic level. These results highlight that although the socioeconomic level produces limitations in communicative skills, there would still be no visible effects in the early stages of development. Further research must be carried out to corroborate this claim.

and Golombek DA () Is the binge-eating disorder a circadian disorder? Front. Nutr. :. doi: .