EEG, Sleep, and the Menstrual Cycle: Elasticity Before Performance

The Movement of Waters, N1, N2, N3, Phasic REM, and Tonic REM

Maybe we need to begin with a simple sentence:

no body performs the same way every day.

School, sports, music, work, and digital life often treat the body as a linear machine: sleep, wake up, study, produce, compete, respond. But living bodies are rhythmic. We breathe in cycles. We sleep in cycles. We learn in cycles. We menstruate in cycles. We dream in cycles.

In BrainLatam2026 language, this is not weakness. It is elasticity.

Elasticity is the ability to adjust performance to the real body, instead of forcing the body to obey an artificial calendar of productivity.

The Movement of Waters: the body is not a machine, it is a cycle

When speaking about ancestral Amerindian knowledge, we need to be careful not to treat different peoples as if they were one single tradition. Each people has its own language, territory, cosmology, and way of transmitting knowledge.

But there is one image that helps us: the Movement of Waters.

In Latin American decolonial readings, especially in the concepts of cuerpo-territorio and agua-cuerpo-territorio, body, water, and territory do not appear as separate realities. Sofia Zaragocin proposes the bilingual concept agua-cuerpo-territorio / water-body-territory, bringing body-territory and water-territory together through decolonial feminist debates in the Americas.

The water of the river is not separate from the water of the body. Sweat, tears, blood, amniotic fluid, and the ocean belong to the same continuity of life.

The body that menstruates is not “failing.”
It is showing tide.

The body that dreams is not “disconnected.”
It is reorganizing internal waters.

The body that goes through puberty, PMS/SPM, or menopause is not “unstable.”
It is changing the course of the river.

The idea of body-territory, discussed in dialogue with Indigenous and community feminisms in Latin America, reinforces that violence against the body and violence against the land cannot be separated, especially in the face of extractivism, colonialism, and climate catastrophe.

In the BrainLatam2026 reading:

the menstrual cycle is Movement of Waters.
Sleep is Movement of Waters.
EEG records the waves of this movement.
Performance needs to learn how to navigate, not how to dam the river.

EEG and sleep stages: N1, N2, N3, tonic REM, and phasic REM

Sleep is not a single block. It alternates between NREM and REM. NREM is divided into N1, N2, and N3. In a typical night, the body moves through cycles of about 90 to 110 minutes, repeating these stages several times.

N1 is the entrance into sleep. It is the riverbank. The body begins to leave wakefulness, but it still listens to the external world.

N2 is a more stable sleep stage. In EEG, sleep spindles and K-complexes appear, important markers for sleep protection and memory consolidation. It is as if the body begins to close some doors to protect the nighttime crossing.

N3 is deep slow-wave sleep. It is the deep water. EEG shows delta waves, and the body enters a stronger state of restoration, with less openness to the external world. It is also the stage that we can bring close to the idea of a literal “brain washing”: during deep sleep, the glymphatic system increases the circulation of cerebrospinal fluid and helps remove metabolic waste from the brain. In simple terms, while the body dives into N3, the brain intensifies processes of cleaning, drainage, and reorganization. That is why sleeping poorly is not only “resting less”; it is reducing the opportunity for the brain to wash its own internal waters. Recent reviews describe glymphatic clearance as a process of metabolic waste removal through cerebrospinal fluid transport, strongly connected to sleep physiology.

In the image of the Movement of Waters, N3 is when the internal river runs deeper, carrying away the remains of the day, excess tension, and residues of brain metabolism.

REM is also not homogeneous. We can think of tonic REM, more continuous, and phasic REM, marked by bursts of rapid eye movements. Recent studies suggest that these microstates may respond differently to external stimuli, showing that even the “dreaming sleep” has distinct layers of opening and closing to the territory.

So it is not enough to ask:

“Did you sleep well?”

The BrainLatam2026 question is:

Was the body able to enter N1?
Did it remain in N2?
Did it deepen into N3?
Did it allow the brain to wash its internal waters?
Did it move through tonic REM and phasic REM?
Did the menstrual cycle, pain, shame, screens, heat, or anxiety alter this crossing?

Dreaming also happens in NREM

For a long time, common sense associated dreaming mainly with REM sleep. Today, EEG shows a more complex story.

A 2025 study in Sleep Advances used high-density EEG and machine learning to classify the presence or absence of dream experience during N2 sleep, a NREM stage. The study worked with reports collected after awakenings and showed that dream experience can also be investigated outside REM.

Another 2025 study, published in Nature Communications, presented an EEG and dream mentation database with reports in both REM and NREM. The article shows that conscious experience reports can be predicted from EEG features in both REM and NREM.

This is central.

Dreaming is not only the strong imagery of REM.
Dreaming may be a reorganization of the Movement of Waters across different depths of sleep.

N2 can reorganize information.
N3 can wash, restore, and stabilize.
Phasic REM can intensify images and emotions.
Tonic REM can maintain another form of listening to the territory.

Menstrual cycle, puberty, and executive functions

The menstrual cycle should not be used to diminish anyone. It is not an argument to say that girls “think less” or that women are “unstable.” That would be biologically poor and socially dangerous.

The point is different: the body changes, and education needs to learn how to listen to those changes.

A 2024 article on brain dynamics across the menstrual cycle showed that cycle phases and hormonal fluctuations modulate brain network dynamics in healthy women, including networks related to attention, control, salience, somatomotor processing, and subcortical regions.

In adolescence, this becomes even more delicate. Menarche is not only a biological event. It reorganizes sleep, belonging, shame, self-care, body-territory, and the way one exists at school.

PMS/SPM should not be a joke. It should also not be used as an excuse for humiliation. It can involve pain, irritability, tiredness, sleep changes, difficulty focusing, and emotional sensitivity. On some days, the best performance may be a test, training, stage, or a long class. On other days, it may be reviewing, breathing, reducing load, sleeping better, and avoiding unnecessary exposure.

This is elasticity.

Executive functions — attention, inhibition, cognitive flexibility, working memory, and planning — depend on sleep, stress, and body rhythms. A 2024 systematic review on menstrual cycle, circadian rhythm, and physical performance concluded that there are signs of interaction between time of day, cycle phase, and performance, but also reinforced that findings still require caution because of the limited number of studies and methodological differences.

In BrainLatam2026 language:

poor sleep reduces elasticity.
Low elasticity pushes the body into Zone 3.
Zone 3 transforms performance into survival.

Menopause: the river changes course

Menopause also needs to leave the place of silence. It is not the end of intelligence, creation, or performance. It is a bodily crossing.

A 2023 review on cognition in perimenopause points out that recent research associates this transition with possible difficulties in processing speed, attention, and working memory.

In the image of the Movement of Waters, menopause does not dry the river. It changes its course. The body asks for another kind of listening, another rhythm, another pedagogy of performance.

The question for Brain Bee

The scientific question is:

how do the menstrual cycle, sleep, dreaming, and hormonal transitions modulate EEG, executive functions, and performance?

A BrainLatam2026 study could follow adolescents and adults across different phases of the cycle, with consent, privacy, and no intimate exposure. We could measure sleep EEG, EEG during attention tasks, ECG/HRV, breathing, GSR, actigraphy, body temperature, sleep quality, pain, perceived energy, working memory, inhibitory control, cognitive flexibility, and sense of belonging.

The hypothesis would be:

when we respect N1, N2, N3, tonic REM, phasic REM, the Movement of Waters, and body-territory, performance stops being linear pressure and becomes intelligent elasticity.

Closing

Elasticity before performance.

Before demanding focus, ask about sleep.
Before demanding results, ask about the body.
Before calling it instability, ask about the cycle.
Before demanding constancy, ask about the Movement of Waters.

High performance does not begin with effort. It begins with the body’s capacity to move through N1, N2, N3, tonic REM, and phasic REM without being hijacked by pain, stress, shame, heat, screens, or linear pressure.

The body that menstruates, matures, dreams, and goes through menopause is not a lesser body.

It is body-river.
It is liquid APUS.
It is Damasian Mind in tide.
It is the Movement of Waters trying to keep life, memory, dreaming, and performance within the same territory.

Post-2021 references used

Patel, A. K. et al. Physiology, Sleep Stages, StatPearls / NCBI Bookshelf, 2024.
https://www.ncbi.nlm.nih.gov/books/NBK526132/

Feriante, J. et al. Physiology, REM Sleep, StatPearls / NCBI Bookshelf, 2023.
https://www.ncbi.nlm.nih.gov/books/NBK531454/

Targeting Sleep Physiology to Modulate Glymphatic Brain Clearance, Physiology, 2024.
https://journals.physiology.org/doi/10.1152/physiol.00019.2024

Corbali, O. et al. Glymphatic system in neurological disorders and neurodegenerative diseases, Frontiers in Neurology, 2025.
https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2025.1543725/full

Zaragocin, S. Agua-cuerpo-territorio / Water-body-territory, Political Geography, 2024.
https://www.sciencedirect.com/science/article/abs/pii/S0962629824001793

D’Arcangelis, C. L.; Quiroga, L. Cuerpo-Territorio: Towards Feminist Solidarities in the Americas, Revista Eletrônica da ANPHLAC, 2023.
https://revista.anphlac.org.br/anphlac/article/view/4140

Moctezuma, L. A. et al. From high- to low-density EEG for automatic classification of dream experiences during stage 2 of NREM, Sleep Advances, 2025.
https://academic.oup.com/sleepadvances/article/6/4/zpaf066/8267695

Wong, W. et al. A dream EEG and mentation database, Nature Communications, 2025.
https://www.nature.com/articles/s41467-025-61945-1

Ameen, M. et al. Differential Brain and Eye Responses to External Auditory Information in Phasic and Tonic REM Sleep, World Sleep, 2023; related abstract in Sleep, 2024.
https://uni-salzburg.elsevierpure.com/en/publications/differential-brain-and-eye-responses-to-external-auditory-informa

Avila-Varela, D. S. et al. Whole-brain dynamics across the menstrual cycle: the role of hormonal fluctuations and age in healthy women, npj Women’s Health, 2024.
https://www.nature.com/articles/s44294-024-00012-4

Beníčková, M. et al. Effect of circadian rhythm and menstrual cycle on physical performance in women: a systematic review, Frontiers in Physiology, 2024.
https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2024.1347036/full