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Updated: May 12, 2026

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Anything but small: Microarousals stand at the crossroad between noradrenaline signaling and key sleep functions

Anita Lüthi1, Maiken Nedergaard2

  • 1Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.

Neuron
|January 14, 2025
PubMed

Insights

Microarousals (MAs) are brief awakenings during sleep. New research suggests these MAs are vital for healthy sleep, supporting brain restoration and plasticity by regulating noradrenaline levels.

Area of Science:

  • Neuroscience
  • Sleep Science
  • Physiology

Background:

  • Continuous sleep is essential for brain and body restoration, while fragmented sleep impairs cognition and health.
  • Microarousals (MAs), brief awakenings during sleep, are key indicators of sleep disorders.
  • Recent rodent studies link MAs during non-rapid eye movement (NREM) sleep to noradrenaline (NA) fluctuations and other physiological rhythms.

Purpose of the Study:

  • To investigate the biological roles of MAs in healthy sleep dynamics.
  • To propose a model where MAs modulate the benefits of NREM sleep based on NA fluctuations.
  • To explore the implications of MA dynamics in neurodegenerative diseases and stress.

Main Methods:

  • The study integrates findings from recent rodent research on MA generation.
  • It analyzes the relationship between NA fluctuations, MAs, and NREM sleep.
  • The research proposes a theoretical framework based on existing data.

Main Results:

  • MAs are proposed to be integral to healthy sleep, driven by infraslow NA fluctuations.
  • An inverted U-shaped relationship is hypothesized between NA fluctuations and NREM sleep benefits via MAs.
  • Both weakened and exacerbated NA fluctuations can negatively impact sleep quality and restorative functions.

Conclusions:

  • Microarousals play a crucial role in promoting the restorative and plasticity-promoting functions of sleep.
  • Understanding MA dynamics offers new insights into normal and pathological arousal patterns during sleep.
  • Dysregulation of MAs, linked to NA signaling, may contribute to cognitive decline and health issues in various conditions.
Keywords:
AASM scoring rulescerebrospinal fluidglymphatic systeminfraslow fluctuationslocus coeruleusmicroarousalsnoradrenalinesleepsleep fragmentationvasomotion

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