What is the clinical evidence from this study?

Study design: Observational. Population: Healthy adults (n=52). Intervention: Continuous wearable locomotor and autonomic monitoring paired with fMRI. Primary outcome: Circadian brain-body organization archetypes.

February 16, 2026Open Access

Control vs. salience: a new axis of circadian brain-body organization

Key Result

Continuous wearable monitoring and fMRI in healthy adults identified a Control-Salience axis of circadian organization, stratifying individuals into stability-anchored or coupling-anchored profiles.

Study Design

Type

Observational (n=52)

Multicenter

Yes

Structured PICO

Population

52 healthy young adults

Outcome

Control-Salience axis of brain-body organization derived from circadian feature vectors (stability, amplitude, acrophase, and ACC-BPM alignment/lag) and structural/resting-state fMRIsurrogate

Circadian organization follows a Control-Salience axis linking locomotor-autonomic rhythms with distinct neural network connectivity, refining mechanistic models of circadian risk.

Limitations

Accelerometry coverage exceeded heart rate coverage by over twofold during daytime hours, raising possible noise asymmetries.
MRI scan time and timing varied widely across participants (from 9:00 AM to 10:30 PM).
Only one fMRI scan of approximately 7.8 minutes was performed per participant, which is relatively short for resting-state network estimation.
Susceptibility distortion correction was not applied to fMRI data.
Brain-circadian associations were exploratory, and none of the correlations in the partial-r matrices survived multiple comparison correction.
Participants were not pre-screened for alarm clock use, shift work, or other lifestyle factors that could influence circadian rhythms.
The single-component 24-hour cosinor model may not capture multi-modal circadian patterns.
Conservative autocorrelation gating for PPG may under-sample very high heart rates.

Abstract

Circadian robustness is usually cast on a single weak-strong continuum, but multi-system data suggest a different picture. We followed 52 healthy young adults for ~30 days with wearable locomotor (accelerometry; ACC) and autonomic (heart rate; BPM) signals and paired these with structural and resting-state fMRI. From person-level circadian feature vectors (stability, amplitude, acrophase, and ACC-BPM alignment/lag), we uncovered a Control-Salience axis of brain-body organization. A control-anchored archetype showed ACC-dominant rhythms-higher activity stability and amplitude, later BPM acrophase, and a longer ACC → BPM phase lead-together with stronger connectivity in cognitive control networks. A complementary salience-anchored archetype exhibited BPM-dominant rhythms-earlier BPM acrophase, higher BPM relative amplitude, tighter ACC-BPM coupling-and stronger connectivity in salience and attention networks. Across individuals, cross-system alignment (ACC-BPM lag) tracked control-network coherence, whereas rhythm timing and amplitude related selectively to cortical geometry and network strength. These findings recast circadian health as axis-based and system-specific: individuals organize along a spectrum from stability-anchored, locomotor-led profiles to coupling-anchored, autonomic-dominated profiles with distinct neural correlates. The Control-Salience axis refines mechanistic models of circadian risk and points to alignment-aware, network-targeted strategies for monitoring and intervention.

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