Sleep to consciousness: how the brain goes from dreams to reality

Summary: Every morning, your brain suffers a precise sequence to change your sleep to vigil, reorienting it to the world. A study that uses high -density EEG recordings found that the awakening begins in the frontal regions and extends backwards, with different patterns depending on whether it wakes up from the dream REM or not REM.

In non -REM sleep, slower waves precede a faster activity similar to vigil, while the dream REMs directly to the vigil. These findings shed light on why sometimes we feel alert and other times stunned, with implications to understand and treat sleep disorders.

Key facts:

Sequential awakening: brain activity moves from frontal to later regions during vigil. No REM shows slower transitions. Tranquility clues: Certain slow waves before awakening can improve the alert state, while others get worse.

Source: Knaw

Every morning, your brain embarks on a remarkable series of events: it makes the transition of being asleep, potentially in an alternative reality, to wake up.

In a short time, you regain vigil awareness, reorient and re -connect with your environment, preparing to interact with the world again.

But how does your brain achieve this transition so safely and efficiently?

Credit: Neuroscience News

To better understand the Awakening brain, the researchers of the Institute of Neuroscience of the Netherlands and the University of Lausana analyzed more than 1,000 awakenings using high density EEG recordings in second place.

The study, published in the current biology, reveals that the brain does not wake up at the same time. Instead, orchestra a precise sequence of activation.

Moving waves

The researchers worked with high density EEG data, which offers information about time and location of brain activity. When observing the progression of the activity throughout the brain of the awakening, they observed a clear sequence: it begins in the regions of the central and frontal brain and gradually spreads towards the back of the brain.

Aurélie Stephan, first author, is not surprised by this sequence of events: “This progression probably reflects how the signs of subcortical excitation centers (deeper in the brain) reach the cortex, with shorter paths to frontal and longer areas towards regions further back.”

Sleep stages: Rem vs no rem

To better understand how the brain navigates at any time, the researchers specifically studied the patterns of awakening in two stages: Dream REM, commonly associated with vivid dreams and non -REM dream, also known as deep sleep.

When the participants woke up from the non -REM sleep, their brain activity first showed a brief increase in the slower waves of a dream, immediately followed by a faster activity related to vigil. When the participants woke up from the ReM dream, the slower waves were omitted, which led to a more direct impulse in a faster brain activity.

“The brain responds differently to the excitation signals depending on the scenario in which it is,” explains Stephan. “In the non -REM dream, the neurons that connect the excitation centers with the alternative cortex between the states of activity and the silence, a dynamic known as” connectability. “

As a result of this bistability, any stimulus of excitation first triggers a slow wave, before the transition to a faster activity. On the contrary, Rem Sleep does not have this bietable pattern, so the cortex responds immediately with the rapid activity, similar to Wake’s.

Understand sleepiness and sleep visitors

The researchers also investigated how sleepy a participant felt when they woke up. While participants felt the most sleeping when they woke up from ReM sleep, Stephan is more intrigued by the impact of slow waves on the non -REM sleep stages.

“We find a new aspect in which slow waves can present very different and opposite behaviors. Some slow waves are actually acting as excitation elements: they are part of” Wake up! ” sign.

“The more these waves occur just before awakening, the more alert tends to feel when you wake up. While the other slow waves, whether present before waking up or persisting later, are the reason why we sometimes feel so drows.

Stephan hopes that these findings can be used for future research on sleep disorders, such as insomnia or conditions that involve incomplete awakenings. “If we understand the process more, we can also identify better hyperatousal signs in sleep disorders,” he concludes.

In general, Stephan is excited about future roads. “This study provides a new perspective. The brain trip from sleep to vigil still, offering a window to one of the most fundamental transitions in human consciousness.”

About this dream, awareness and neuroscience research news

Author: Eline Feenstra
Source: Knaw
Contact: Eline Feenstra – Knaw
Image: The image is accredited to Neuroscience News

Original research: open access.
“The cortical activity when awakening of sleep reveals space-time gradients consisting of sleep stages in the human EEG” by Aurélie Stephan et al. Current biology

Abstract

Cortical activity when awakening sleep reveals space-time gradients consisting of sleep stages in the human EEG

How does the dream brain awake?

Several studies have suggested that the process of awakening occurs asynchronically through the regions of the brain, but the precise nature of these changes and how they are reflected in human electroencephalography (EEG) is still unknown.

Here, we register 1,073 awakenings and excitations with EEG of high density and brain activity mapped in a second -second time scale around the start of movement using the source modeling.

We found that cortical activity when awakening progressed along highly consistent space gradients.

In the awakenings and excitations of the dream of non -fast ocular movement (NREM), transient increases in low frequency power preceded increases in high frequency power in a few seconds, while the awakenings of the REM sleep were mainly characterized by increases in high frequency power increases.

Regardless of the sleep stage, the high frequency changes were first seen on the front of the occipital and lower-temporal cortical areas, while the low frequency changes in the NREM sleep began in a “centers” access point “, progressed frontally, and reached the lower and lower-temporal regions.

Finally, the presence of these space-time excitation patterns during sleep, before the participants woke up for the sounds, was followed by lower drowsiness ratings when awakening.

These results indicate a consistent space-time EEG firm of the process of awakening that probably reflects the structural organization of excitation systems.

It is important to highlight that a transitory increase in slow EEG frequencies, which are normally associated with sleep, is inherent in the excitation process and correlates functionally with feeling more awake when it wakes up from the NREM dream.

These findings have important implications for the interpretation of excitation signals and the detection of incomplete awakenings in sleep disorders.