How the brain's activity, energy use and blood flow change as people fall asleep

A new study by investigators  has used next-generation imaging technology to discover that when the brain is falling asleep, it shows a coordinated shift in activity.

The researchers found that during NREM (non-rapid eye movement) sleep, parts of the brain that handle movement and sensory input stay active and keep using energy, while areas involved in thinking, memory and daydreaming quiet down and use less energy. Their results are published in Nature Communications.

This research helps explain how the brain stays responsive to the outside world even as awareness fades during sleep.

By revealing how brain activity, energy use, and blood flow interact during sleep, these findings, and the imaging tools scientists used to uncover them, offer new insights into the mechanisms of neurological and sleep-related diseases.

The body cycles through two types of sleep several times each night: NREM and REM (rapid eye movement). NREM is the deep, restorative stage of sleep that plays a key role in physical health, brain function and disease prevention. Yet, many of its underlying processes and impacts on long-term health remain poorly understood. Previous studies have suggested that NREM helps clear waste from the brain.

Using a new tri-modal EEG-PET-MRI technique that combines EEG to study brain activity, fMRI to analyze blood flow, and functional PET (fPET)-FDG to monitor glucose metabolic dynamics, researchers examined the brains of 23 healthy adults during brief afternoon sleep sessions.

The researchers found that energy use and metabolism decrease as sleep deepens, while blood flow becomes more dynamic, especially in sensory areas that stay relatively active. At the same time, higher-order cognitive networks quiet down, and cerebrospinal fluid flow increases. Together, these findings support the idea that sleep helps clear waste from the brain while maintaining sensitivity to sensory cues that can trigger awakening.

Simultaneous EEG-PET-MRI identifies temporally coupled and spatially structured brain dynamics across wakefulness and NREM sleep", Nature Communications (2025). DOI: 10.1038/s41467-025-64414-x

Physicists create the smallest pixel in the world 

Smart glasses that display information directly in the field of vision are considered a key technology of the future—but until now, their use has often failed due to cumbersome technology. However, efficient light-emitting pixels are ruled out by classical optics if their size is reduced to the wavelength of the emitted light.

Now, physicists  have taken a decisive step toward luminous miniature displays and, with the help of optical antennas, have created the world's smallest pixel to date.

With the help of a metallic contact that allows current injection into an organic light-emitting diode while simultaneously amplifying and emitting the generated light, they have created a pixel for orange light on an area measuring just 300 by 300 nanometers. This pixel is just as bright as a conventional OLED pixel with normal dimensions of 5 by 5 micrometers.

To put this into perspective, a nanometer is one millionth of a millimeter. This means that a display or projector with a resolution of 1,920 x 1,080 pixels could easily fit onto an area of just one square millimeter. This, for example, enables integration of the display into the arms of a pair of glasses from where the light generated would be projected onto the lenses.

Cheng Zhang et al, Individually addressable nanoscale OLEDs, Science Advances (2025). DOI: 10.1126/sciadv.adz8579

Life's Ingredients Found Frozen Beyond The Milky Way For First Time

For the first time, astronomers have seen life's building blocks in ice beyond the borders of our galaxy.
Among a mix of complex organic molecules trapped in ice circling a newborn star in the Large Magellanic Cloud, researchers found ethanol, acetaldehyde, and methyl formate – compounds that have never before been spotted in ice form outside the Milky Way.
Moreover, another identified compound, acetic acid, has never before been conclusively identified in ice anywhere in space.

The discovery by astrophysicists suggests that the ingredients for the chemistry that gives birth to life are widespread and robust across the cosmos, and not limited to our own galaxy.
Complex organic molecules (COMs) in an astrophysical context are molecules with at least six atoms, at least one of which is carbon. The category includes molecules such as ethanol (CH₃CH₂OH), methyl formate (HCOOCH₃), and acetaldehyde (CH₃CHO), as well as larger molecules such as iso-propyl cyanide ((CH3)2CHCN).

They're important to scientists because they're the chemical precursors to the molecules that build life, such as amino acids, sugars, and nucleobases. Finding them in space, therefore, sheds light on the origins of prebiotic chemistry and where those precursor compounds were likely forged before Earth was even born.

https://iopscience.iop.org/article/10.3847/2041-8213/ae0ccd