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Por qué se duerme mal la primera noche en un lugar desconocido

Pasar la primera noche en un hotel, una casa ajena o cualquier sitio nuevo suele traer consigo vueltas en la cama y sueño interrumpido. ¿Por qué el cerebro parece ponerse en guardia justo cuando más necesitamos descansar?
Un grupo de científicos de la Universidad de Nagoya, en Japón, se propuso resolver este misterio tan frecuente.
Lo que descubrieron podría cambiar nuestra forma de entender el insomnio en lugares desconocidos. Tras estudiar ratones, el equipo identificó un grupo de neuronas llamado IPACL CRF.
Estas células se activan en cuanto el animal entra en un entorno nuevo y liberan una sustancia llamada neurotensina, que mantiene la mente despierta.

“El cerebro se mantiene alerta para protegernos de posibles peligros cuando no reconoce el lugar”, explicó el doctor Daisuke Ono, responsable del estudio.
Ono detalló: “La amígdala extendida es una región que procesa emociones y estrés en los mamíferos. Allí, las neuronas IPACL CRF producen neurotensina y responden al detectar un ambiente desconocido”.
Dormir mal la primera noche no es casualidad. Los experimentos demostraron que, si los científicos desactivaban estas neuronas, los animales conciliaban el sueño rápidamente aunque estuvieran en lugares nuevos. Si las estimulaban, los ratones permanecían mucho más tiempo despiertos.

La neurotensina no actúa sola. Después de liberarse, llega a otra región del cerebro llamada sustancia negra, que regula el movimiento y la atención.
“La neurotensina luego afecta la sustancia negra, un área cerebral que controla el movimiento y la atención”, subrayó Ono. Esta conexión ayuda a entender por qué, por instinto, el cerebro se mantiene medio despierto en lugares desconocidos.
El fenómeno se conoce como “efecto de la primera noche”: la mente nunca se relaja del todo hasta sentirse segura.
El equipo recordó que este mecanismo no es exclusivo de los ratones. “Tanto la amígdala extendida como la sustancia negra existen en todos los mamíferos, incluso en humanos”, explicaron los científicos. Por eso es probable que tengamos circuitos cerebrales parecidos.

Durante décadas, los médicos han visto que dormir en un sitio nuevo despierta un “modo guardián” en el cerebro. Una parte se mantiene activa, como si hiciera vigilia.
“El cerebro parece mantener un ojo abierto hasta confirmar que el entorno es seguro”, resumió el estudio. Este sistema tiene sentido desde la evolución. Quien dormía profundamente en un lugar extraño podía estar en peligro. La vigilancia nocturna nos ayudó a sobrevivir.
El trabajo, publicado en Proceedings of the National Academy of Sciences, no solo revela el mecanismo, sino que podría abrir la puerta a nuevos tratamientos.

Muchas personas con insomnio, ansiedad o TEPT sufren vigilancia nocturna excesiva. Los científicos creen que los fármacos que actúan sobre la vía de la neurotensina podrían ayudar a dormir mejor.
Entender cómo funciona este circuito podría ser útil para desarrollar terapias que mejoren el sueño en personas con trastornos de ansiedad.
También podría ayudar a quienes viajan frecuentemente por trabajo o sufren jet lag, ya que conocer el mecanismo facilitaría estrategias para adaptar el cuerpo a nuevos horarios y ambientes.

Para ilustrar el hallazgo, los autores mostraron imágenes de las neuronas IPACL CRF, marcadas en verde, que se activan cuando los ratones exploran un entorno inédito y liberan neurotensina para mantener el estado de alerta. El equipo cree que este avance es clave para entender cómo el cerebro regula el sueño y la vigilancia.
“Es probable que nuevos tratamientos puedan dirigirse a este circuito y mejorar la calidad de vida de quienes sufren insomnio o ansiedad”, concluyeron los investigadores. Así, el descubrimiento transforma una incomodidad nocturna en una pista sobre cómo nuestro cerebro nos protege.
La dificultad para dormir en lugares nuevos no es solo una molestia: es una herencia biológica que nos ayudó a sobrevivir.
neurociencia,ratón,cerebro,conexiones neuronales,investigación científica,modelos animales,enfermedades neurológicas
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Modern Love: Un apagón hizo que lo nuestro fuera posible
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Pope Leo says he ‘can’t comment’ on 20-year sentence of Hong Kong pro-democracy activist Jimmy Lai

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Pope Leo XIV this week said he «can’t» comment on the 20-year sentence imposed on a democracy activist in Hong Kong.
«I can’t comment,» the American-born Leo told EWTN News, which covers Catholic news globally, while speaking to reporters in Italy.
He added, «Let’s pray for less hatred and more peace and work for authentic dialogue. God bless you all.»
Hong Kong publisher and democracy activist Jimmy Lai, who is a converted Catholic, was sentenced to 20 years by Beijing last month for violating their 2020 national security law, which U.S. Secretary of State Marco Rubio called «unjust and tragic.»
Pope Leo XIV this week said he «can’t» comment on the 20-year sentence imposed on a democracy activist in Hong Kong. (Christopher Furlong/Getty Images; Anthony Kwan/Getty Images)
«The conviction shows the world that Beijing will go to extraordinary lengths to silence those who advocate fundamental freedoms in Hong Kong,» Rubio said in a statement. «The United States urges the authorities to grant Mr. Lai humanitarian parole.»
The 78-year-old founded the now-closed Hong Kong-based Apple Daily in 1995, while the island was still under British rule.
Lai’s sentence closed one of the country’s most consequential national security cases since Beijing imposed the sweeping new law in 2020 in the wake of months-long anti-Chinese Communist Party protests in 2019, which were sparked by fears Beijing was eroding Hong Kong’s promised autonomy.

Lai has already been in custody since 2020. (Anthony Wallace/AFP via Getty Images)
They were followed by a sweeping security crackdown that criminalized dissent and reshaped the city’s legal system.
CHINA PHONY CONVICTION OF JIMMY LAI IS A WARNING
Lai had been arrested several times during the 2019 protests, and he was detained at his home in 2020. His newspaper was also raided at the time and closed.
He was found guilty in December of attempting to undermine national security.

Jimmy Lai supporters in Los Angeles last month. (Apu Gomes/Getty Images)
President Donald Trump said in December that he had personally urged Chinese President Xi Jinping to release Lai.
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«I spoke to President Xi about it, and I asked to consider his release,» Trump said. «He’s not well, he’s an older man, and he’s not well, so I did put that request out. We’ll see what happens.»
pope leo xiv,china,world,hong kong
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After the strikes, how would the US secure Iran’s enriched uranium?

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When War Secretary Pete Hegseth was asked recently whether U.S. forces would ever move to secure enriched uranium reportedly stored at Iran’s Isfahan nuclear complex, he declined to say, citing operational security.
The exchange highlighted a question the U.S. and Israel’s air campaign alone cannot answer: even if U.S. strikes degrade Iran’s nuclear infrastructure, who would physically secure the enriched uranium, and how?
Iran is believed to possess a significant stockpile of uranium enriched to 60%, near weapons-grade. That material could theoretically be used in multiple nuclear devices if further refined.
Moving from 60% to weapons-grade 90% enrichment requires additional processing, and weaponization would involve further technical steps. But analysts say the more immediate issue is physical control of the material itself.
«If the U.S. wants to secure Iran’s nuclear materials, it’s going to require a massive ground operation,» Kelsey Davenport, director of nonproliferation policy at the Arms Control Association, told Fox News Digital.
Davenport said the highly enriched uranium believed to be stored at Isfahan appears to be deeply buried and contained in relatively mobile canisters. Securing it would likely require locating the full stockpile, accessing underground facilities and safely extracting or downblending the material.
Satellite imagery taken on Jan. 30, 2026 shows a new roof over a previously destroyed building at the Natanz nuclear site. (2026 PLANET LABS PBC/Handout via Reuters)
«It’s not even clear the United States knows where all of the uranium is,» she said, noting that the mobility of storage containers raises the possibility that some material could be moved or dispersed.
The administration repeatedly has said preventing Iran from obtaining a nuclear weapon remains a central objective of Operation Epic Fury.
«Ultimately, this issue of Iran’s nuclear pursuit and their unwillingness through negotiations to stop it is something President Trump has said for a long time needs to be dealt with,» Hegseth said.
Senior administration officials have argued that Iran sought to build up its ballistic missile arsenal in part to create a deterrent shield — enabling Tehran to continue advancing its nuclear program while discouraging outside intervention.
So far, however, the bulk of U.S. strikes have focused on degrading missile launchers, air defenses and other conventional military targets.
Experts note that dismantling missile systems may reduce Iran’s ability to shield a potential nuclear breakout. But physically controlling enriched uranium itself presents a separate and more complex challenge.

This photo released on Nov. 5, 2019, by the Atomic Energy Organization of Iran shows centrifuge machines in the Natanz uranium enrichment facility in central Iran. (Atomic Energy Organization of Iran via AP, File)
Airstrikes versus physical control
Defense officials have acknowledged that degrading nuclear infrastructure from the air is different from safely managing or securing nuclear material.
Airstrikes can destroy centrifuges, power systems and support buildings. But enriched uranium stored underground may remain intact unless it is physically secured, removed or verifiably downblended.
Striking or extracting nuclear material also carries safety risks that military planners must weigh.
If storage casks containing uranium hexafluoride gas were compromised, the material could pose chemical toxicity risks to personnel entering the site without proper protective equipment. Analysts say a conventional strike is unlikely to trigger a nuclear detonation, but dispersal of material could create localized hazards and complicate recovery efforts.
Chuck DeVore, a former Reagan-era defense official who worked on nuclear issues, argued that directly targeting the stockpile may not be a priority under current battlefield conditions.
«You don’t want to release the material into the surrounding areas and cause radioactive contamination,» DeVore said, adding that deeply buried facilities are difficult to reach from the air.
DeVore also downplayed the immediacy of a breakout scenario, arguing that further enrichment, weaponization and delivery would be difficult to execute undetected amid sustained U.S. air operations.
Even if Iran were able to further enrich uranium, he said, assembling a deliverable weapon under active military pressure would present significant technical and operational hurdles.

Trump said that the United States completed a «very successful» strike against Iranian nuclear sites at Fordow, Natanz and Isfahan, saying that Iran’s nuclear enrichment installations have been «obliterated.» (Fox News)
Still, DeVore acknowledged that long-term control of the uranium would ultimately require a political resolution inside Iran and some form of outside oversight.
What would securing it require?
Nonproliferation experts say securing enriched uranium generally involves more than military force. It requires verified accounting of the material, sustained access to storage sites and either removal or downblending to lower enrichment levels suitable for civilian use.
Davenport said internationally monitored downblending would be the safest option if political conditions allow.
«The IAEA remains the best place to go back into Iran to monitor the sites, to try to track down and account for the enriched uranium,» she said, describing downblending as a relatively straightforward technical process compared to attempting to extract and transport highly enriched material in a contested environment.
Both pathways — physical seizure or internationally monitored reduction — depend on conditions that do not currently exist.
Administration officials argue that dismantling Iran’s missile network weakens Iran’s ability to shield a nuclear breakout and reduces the immediate threat to U.S. forces and regional allies.
But suppressing missiles and controlling enriched uranium are separate challenges.
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Destroying infrastructure can slow or disrupt a program. Physically locating, accounting for and securing nuclear material requires sustained access, reliable intelligence and — ultimately — political conditions that allow it.
For now, the administration maintains that Iran will not be allowed to obtain a nuclear weapon. How the enriched uranium itself would be secured remains a question without a public answer.
war with iran,iran,nuclear proliferation,nuclear disasters
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