Does the moon affect our sleep? Research says no

 

June 17, 2014

No correlation between moon phases and human sleep has been found by researchers studying the topic. For centuries, people have believed that the moon cycle influences human health, behavior and physiology. Folklore mainly links the full moon with sleeplessness. "We could not observe a statistical relevant correlation between human sleep and the lunar phases," remarked researchers after a large study completed.

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Popular beliefs about the influence of the moon on humans widely exist. Many people report sleeplessness around the time of full moon. In contrast to earlier studies, scientists from the Max Planck Institute of Psychiatry in Munich did not observe any correlation between human sleep and the lunar phases. The researchers analyzed preexisting data of a large cohort of volunteers and their sleep nights. Further identification of mostly unpublished null findings suggests that the conflicting results of previous studies might be due to a publication bias.

For centuries, people have believed that the moon cycle influences human health, behavior and physiology. Folklore mainly links the full moon with sleeplessness. But what about the scientific background?

Several studies searched in re-analyses of pre-existing datasets on human sleep for a lunar effect, although the results were quite varying and the effects on sleep have rarely been assessed with objective measures, such as a sleep EEG. In some studies women appeared more affected by the moon phase, in others men. Two analyses of datasets from 2013 and 2014, each including between 30 and 50 volunteers, agreed on shorter total sleep duration in the nights around full moon. However, both studies came to conflicting results in other variables. For example, in one analysis the beginning of the REM-sleep phase in which we mainly dream was delayed around new moon, whereas the other study observed the longest delay around full moon.

To overcome the problem of possible chance findings in small study samples, scientists now analyzed the sleep data of overall 1,265 volunteers during 2,097 nights. "Investigating this large cohort of test persons and sleep nights, we were unable to replicate previous findings,"  " It has been  observed a statistical relevant correlation between human sleep and the lunar phases." Further, his team identified several unpublished null findings including cumulative analyses of more than 20,000 sleep nights, which suggest that the conflicting results might be an example of a publication bias (i.e. the file drawer problem).

The file drawer problem describes the phenomenon, that many studies may be conducted but never reported -- they remain in the file drawer. One much-discussed publication bias in science, medicine and pharmacy is the tendency to report experimental results that are positive or show a significant finding and to omit results that are negative or inconclusive.

Up to now, the influence of the lunar cycle on human sleep was investigated in re-analyses of earlier studies which originally followed different purposes. "To overcome the obvious limitations of retrospective data analysis, carefully controlled studies specifically designed for the test of lunar cycle effects on sleep in large samples are required for a definite answer”

Internet glossary of statistical terms

 

 

Statistics

 

Persons unfamiliar with statistical analysis may find the entries easier to grasp if they are examined in the suggested learning order.

Wide variation in lung cancer rates globally, study finds

 

May 16, 2014

American Cancer Society

Lung cancer rates are dropping in young women in many regions of the globe, the only recent comprehensive analysis of lung cancer rates for women around the world finds. The study points to the success of tobacco control efforts around the world. Lung cancer is now the second leading cause of cancer death in women worldwide. An estimated 491,200 women died of lung cancer in 2012, more than half (57%) of whom resided in economically developing countries.

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The only recent comprehensive analysis of lung cancer rates for women around the world finds lung cancer rates are dropping in young women in many regions of the globe, pointing to the success of tobacco control efforts. However, rates continue to increase among older women in many countries, indicating a need for more concentrated efforts to initiate or expand comprehensive tobacco control programs across the globe to curtail future tobacco-related lung cancer deaths. The study is published early online in Cancer Epidemiology, Biomarkers & Prevention.

Lung cancer is now the second leading cause of cancer death in women worldwide. An estimated 491,200 women died of lung cancer in 2012, more than half (57%) of whom resided in economically developing countries. Differences in smoking patterns account for much of the variation in lung cancer rates around the globe. Smoking in females became common in North America, Northern Europe, Australia, and New Zealand as early as the 1940s, but remained rare throughout the 20th century in the developing world and in places with strong social norms against it, such as the Middle East. Only recently is female smoking becoming more common in many of these countries, because of increasing social acceptance, newly open markets, and/or targeted marketing by the tobacco industry.

Because the tobacco epidemic among women has varied globally, researchers led by Lindsey Torre documented and compared contemporary trends in lung cancer mortality, to identify opportunities for intervention. They used the World Health Organization's Cancer Mortality Database covering populations on 10 six continents to calculate age-standardized lung cancer death rates during 2006 to 2010 and annual percent change in rates for available years from 1985 to 2011 and for the most recent five years for which data is available by population and age group (30-49 and 50-74 years).

Lung cancer mortality rates among young women (30-49 years) were stable or declining in 47 of the 52 populations examined. In contrast, among older women (50-74 years), rates were increasing for more than half (36/64) of populations examined, including most countries in Southern, Eastern, and Western Europe and South America. Lung cancer mortality rates (per 100,000) during 2006-2010 ranged from 0.7 in Costa Rica to 14.8 in Hungary among young women and from 8.8 in Georgia to 120.0 in Scotland among older women. For both age groups, rates were highest in parts of Europe (Scotland, Hungary, Denmark) and North America and lowest in Africa, Asia, and Latin America.

"The widespread reduction in lung cancer we found in young women in many parts of the globe is encouraging, and probably reflects both successful tobacco control efforts and increased awareness about the health hazards of smoking," said Torre. "The greatest opportunity we have right now for slowing a tobacco-fueled epidemic is in those countries where smoking among women is rare, such as Africa and most of Asia. And while decreasing lung cancer death rates are encouraging, many countries have yet to implement the kinds of comprehensive tobacco control measures that have led to drops in other countries."

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Story Source:

The above story is based on materials provided by American Cancer Society. Note: Materials may be edited for content and length.

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Journal Reference:

1. Lindsey A. Torre, Rebecca L. Siegel, Elizabeth M. Ward, and Ahmedin Jemal. International Variation in Lung Cancer Mortality Rates and Trends among Women. Cancer Epidemiol Biomarkers, May 2014 DOI: 10.1158/1055-9965.EPI-13-1220

Unhappiness by the Numbers: 2012 Depression Statistics

 

Depression statistics - infographic - click link

 

 

En las ciudades pequeñas hay más suicidios

 

 

Los investigadores se preguntan qué factores en el menor tamaño de las urbes son los que influyen en estos sucesos

Las ciudades son beneficiosas para sus habitantes, estas ventajas son fáciles de observar al comparar urbes de distintos tamaños. Según crecen, la cantidad de trabajos, casas y consumo de agua aumenta con junto a la población.

Pero los ingresos, la productividad y los depósitos bancarios escalan aún más rápido, a un índice mayor que el aumento de población, o superlinealmente. La población de las grandes ciudades se beneficia claramente de una economía de escala que también mejora su calidad de vida. Y cuando más grande sea la ciudad, mayor será el beneficio.

Aunque también hay cualidades negativas que escalan de forma lineal con el tamaño de la ciudad: el coste de la vida y la contaminación, por ejemplo.

Se sabe muy poco del impacto que tienen estos factores negativos sobre los residentes, así que una pregunta importante es si estos cambian de forma negativa el comportamiento humano.

Ya tenemos una respuesta a esta pregunta de la mano del investigador de la Universidad Federal de Ceará (Brasil), Hygor Piaget Melo y un par de compañeros suyos. Estos científicos han medido cómo escalan la tasa de homicidios, suicidios y accidentes de tráfico respecto al tamaño de las ciudades.

Se podría imaginar que estos indicadores irán de la mano con los indicadores urbanos negativos del coste de la vida y una mayor contaminación. Pero Melo y compañía afirman que la relación no es tan directa como se podría pensar y sus resultados ofrecen sorpresas importantes.

El estudio del escalado de las magnitudes se conoce como alometría. El ejemplo más famoso probablemente sea la ley de Kleiber, que afirma que el metabolismo basal de los animales escala a una potencia de 3/4 respecto a su masa. Los biólogos saben que esta relación es cierta en hasta 27 órdenes de magnitud, desde las bacterias hasta las ballenas azules.

Y en los últimos años los antropólogos han descubierto que se pueden aplicar leyes alométricas parecidas para describir distintas propiedades de las ciudades. Los sueldos escalan de forma superlineal con el tamaño de las ciudades, una de las razones por las que la gente supuestamente se siente atraída por las ciudades. Los trabajos escalan de la misma manera. Por el contrario, determinadas características, la cantidad de gasolineras por ejemplo, escalan de forma sublineal.

Pero el auténtico interés de Melo y su equipo está en el índice de escalado de homicidios, suicidios y accidentes de tráfico mortales. Han recogido datos sobre la cifra de suicidios, homicidios y muertes en accidentes de tráfico para todas las ciudades de Brasil y para cada condado de Estados Unidos. Después los han comparado con el tamaño de las poblaciones.

Los resultados no son exactamente lo que cabría imaginar. Resulta que los homicidios escalan de forma superlineal. Así que las grandes ciudades tienen más asesinatos per cápita que las pequeñas.

Por el contrario, las muertes por accidente de tráfico escalan de forma isométrica. Es decir, la cantidad de muertes per cápita es la misma para cualquier ciudad, independientemente del tamaño.

Pero la verdadera sorpresa es la tasa de suicidios, que escalan de forma sublineal. Es decir, en las grandes ciudades hay menos suicidios per cápita que en las pequeñas.

Eso hace surgir una pregunta interesante. Si el tamaño de la población es un factor que influye en el índice de suicidios, ¿cuál es la naturaleza de la causa y el efecto?

Los investigadores sugieren que la intensidad emocional que se asocia con el suicidio podría disiparse más fácilmente en las grandes ciudades, donde hay más gente que ayude a llevar la carga, una idea que se conoce como epidemia emocional.

"Este fenómeno puede explicar la atenuación sistemática a través de la red social de los estados emocionales contagiosos de los potenciales suicidas", afirman. Dicho de otro modo, los suicidios son básicamente un fenómeno social.

No son los primeros datos que apuntan en esta dirección. Los epidemiólogos saben desde hace tiempo que los índices de suicidio descienden en época de guerra, quizá debido al mismo fenómeno, que la gente se une en tiempos difíciles, algo que reduce las tendencias suicidas.

Si ese es el caso, entonces las grandes ciudades y las zonas de guerra tienen más en común de lo que podría parecer a primera vista.

Ref: arxiv.org/abs/1402.2510 : Señales Estadísticas de la Influencia de la Sociedad en los Suicidios