ArticlePLoS biology2020
Time of day is associated with paradoxical reductions in global signal fluctuation and functional connectivity.
Article in PLoS biology, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. Cited by 61 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Who cites it
61 citing papers in PubMed, 119 citations in OpenAlex.
- Trial
- Diurnal Variations and Test-Retest Reliability of Resting-State Functional MRI Metrics.Human brain mapping · 2026Article
- Human Cerebral Blood Flow Activity with Diurnal Variation Differentially Correlated with the Suprachiasmatic Nucleus.The Journal of neuroscience : the official journal of the Society for Neuroscience · 2026Article
- A framework to determine active neurons and networks within the mouse brain reveals how brain activity changes over the course of the day.PLoS biology · 2025Article
- Identification of five sleep-biopsychosocial profiles with specific neural signatures linking sleep variability with health, cognition, and lifestyle factors.PLoS biology · 2025Article
- Longitudinal changes in brain asymmetry track lifestyle and disease.Nature communications · 2025Article
- Multimodal population study reveals the neurobiological underpinnings of chronotype.Nature human behaviour · 2025Article
- Excitation-inhibition balance abnormally shapes structure-function coupling of gray matter in Parkinson's disease.NPJ Parkinson's disease · 2025Review
- The functional overlap between respiration and global signal and its behavioral relevance.Communications biology · 2025Article
- Longer scans boost prediction and cut costs in brain-wide association studies.bioRxiv : the preprint server for biology · 2025Article
- Considering the interconnected nature of social identities in neuroimaging research.Nature neuroscience · 2025Review
- Group-to-individual generalizability and individual-level inferences in cognitive neuroscience.Neuroscience and biobehavioral reviews · 2025Review
- Wearables in Chronomedicine and Interpretation of Circadian Health.Diagnostics (Basel, Switzerland) · 2025Review
- Test-retest reliability of dynamic functional connectivity parameters for a two-state model.Network neuroscience (Cambridge, Mass.) · 2025Article
- Brain connectivity correlates of breathing and cardiac patterns in epilepsy: A study including SUDEP cases.Imaging neuroscience (Cambridge, Mass.) · 2025Article
- Global signal regression reduces connectivity patterns related to physiological signals and does not alter EEG-derived connectivity.Frontiers in neuroimaging · 2025Article
- Circadian Rhythms Tied to Changes in Brain Morphology in a Densely Sampled Male.The Journal of neuroscience : the official journal of the Society for Neuroscience · 2024Article
- Brain-wide functional connectivity artifactually inflates throughout functional magnetic resonance imaging scans.Nature human behaviour · 2024Article
- Diurnal Fluctuations in Steroid Hormones Tied to Variation in Intrinsic Functional Connectivity in a Densely Sampled Male.The Journal of neuroscience : the official journal of the Society for Neuroscience · 2024Article
- Circadian rhythms tied to changes in brain morphology in a densely-sampled male.bioRxiv : the preprint server for biology · 2024Article
1 more citing papers are in PubMed but not listed here.
Corrections and comments
- Erratum issued
Authors and funding
5 authors at 1 institution in 3 countries.
Funding
Abstract
The brain exhibits substantial diurnal variation in physiology and function, but neuroscience studies rarely report or consider the effects of time of day. Here, we examined variation in resting-state functional MRI (fMRI) in around 900 individuals scanned between 8 AM and 10 PM on two different days. Multiple studies across animals and humans have demonstrated that the brain's global signal (GS) amplitude (henceforth referred to as "fluctuation") increases with decreased arousal. Thus, in accord with known circadian variation in arousal, we hypothesised that GS fluctuation would be lowest in the morning, increase in the midafternoon, and dip in the early evening. Instead, we observed a cumulative decrease in GS fluctuation as the day progressed. Although respiratory variation also decreased with time of day, control analyses suggested that this did not account for the reduction in GS fluctuation. Finally, time of day was associated with marked decreases in resting-state functional connectivity across the whole brain. The magnitude of decrease was significantly stronger than associations between functional connectivity and behaviour (e.g., fluid intelligence). These findings reveal time of day effects on global brain activity that are not easily explained by expected arousal state or physiological artefacts. We conclude by discussing potential mechanisms for the observed diurnal variation in resting brain activity and the importance of accounting for time of day in future studies.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.