Raphael Vallat

Welcome!

I am a French scientist specialized in sleep and dream research.

I am currently a postdoctoral researcher in Matthew Walker's lab at UC Berkeley. My research aims at studying the impact of sleep — or lack thereof — on human health and decision-making. Before that, I obtained a PhD in Neuroscience at the University of Lyon, France. My doctoral project aimed at understanding the neural correlates of dream recall i.e. how and why we sometimes recall our dreams and sometimes forget them.

I also have a strong interest in statistics, machine-learning, and signal processing. I created several open-source Python libraries that are under active development: Pingouin (statistics, +80,000 downloads), YASA (sleep analysis) and EntroPy (signal processing).

Academics

• Education

• Expertise

• Teaching

Publications

Please find below a list of publications (last updated June 2020)
PDF versions are provided for individual, noncommercial purposes only. These files may not be reposted without permission. Copyright and all rights therein resides with the respective copyright holders, as stated within each paper.

• Vallat, Nicolas and Ruby (2020). Brain functional connectivity upon awakening from sleep predicts inter-individual differences in dream recall frequency. SLEEP.
• Vallat*, Shah*, Redline, Attia and Walker (2020). Broken sleep predicts hardened blood vessels. PLoS Biology. * Co-first authors
• Ben Simon*, Vallat*, Barnes and Walker (2020). Sleep Loss and the Socio-Emotional Brain. Trends In Cognitive Sciences. * Co-first authors
• Vallat and Ruby (2019). Is it a good idea to cultivate lucid dreaming? Frontiers in Psychology.
• Plailly, Villalba, Vallat, Nicolas, and Ruby (2019). Incorporation of fragmented visuo-olfactory episodic memory into dreams and its association with memory performance. Scientific Reports, 9, 15687.
• Combrisson, Vallat, ..., and Jerbi (2019). Visbrain: A multi-purpose GPU-accelerated open-source suite for multimodal brain data visualization. Frontiers in Neuroinformatics, 13, 14.
• Vallat (2018). Pingouin: statistics in Python. Journal of Open Source Software, 3(31), 1026.
• Vallat, Meunier, Nicolas, and Ruby (2018). Hard to wake up? The cerebral correlates of sleep inertia assessed using combined behavioral, EEG and fMRI measures. NeuroImage [PDF]
• Vallat, Eichenlaub, Nicolas, and Ruby (2018). Dream recall frequency is associated with medial prefrontal cortex white-matter density. Frontiers in Psychology, 9, 1856.
• Vallat, Eskinazi, Nicolas, and Ruby (2018). Sleep and dream habits in a sample of French college students who report no sleep disorders. Journal of Sleep Research, 27, e12659. [PDF]
• Vallat (2017). Content and frequency of dream reports: psychological and neurophysiological correlates. PhD thesis, Lyon 1 University.
• Combrisson*, Vallat*, ..., and Ruby (2017). Sleep: an open-source python software for visualization, analysis and staging of sleep data. Frontiers in Neuroinformatics, 11. * Co-first authors
• Vallat, Chatard, Blagrove, and Ruby (2017). Characteristics of the memory sources of dreams: a new version of the content-matching paradigm to take mundane and remote memories into account Plos One, 12.
• Vallat, ..., and Ruby (2017). Increased evoked potentials to arousing auditory stimuli during sleep: implication for the understanding of dream recall. Frontiers in Human Neuroscience, 11.

Media outreach

• The sad truth about sleep-tracking devices and apps @ New York Times



• Why do some people always remember their dreams, while others almost never do? @ Discover Magazine



• Vivid dreams and their role in waking life @ WHYY (NPR)



• Fitful nightly sleep linked to chronic inflammation, hardened arteries @ Berkeley News



• Simultaneous EEG and fMRI measure sleep ‘inertia’ @ PhysicsWorld.com



• Brain scans reveal why it takes so long to wake up in the morning @ Inverse.com

Software development

Please visit my GitHub repository for an exhaustive list of the projects/softwares that I am contributing to.

Pingouin

Pingouin is an open-source Python statistical package. Learn more on the documentation, check the code on GitHub, or learn how to perform a two-way mixed-design ANOVA.

Visbrain | SLEEP

The SLEEP module of the Visbrain package is an open-source software for visualization and analysis of sleep polysomnographic data. Learn more on the documentation or read the peer-reviewed publication.

YASA

YASA (Yet Another Spindle Algorithm) is an open-source Python package dedicated to sleep (microstructure) analysis. Among others, it implements several state-of-the-art and validated algorithms to detect spindles, slow-waves, and rapid eye movements. Learn more on the documentation or check the code on GitHub

EntroPy

EntroPy is an open-source Python package for computing several entropy metrics of EEG time-series. Learn more on the documentation or check the code on GitHub.

SleepViz

SleepViz is the (deprecated) MATLAB prototype of SLEEP. Click here for a quick start guide.

Tutorials

Please find below some tutorials regarding the analyses I specialize in.

The Science of Dream Recall

Why do some people remember more of their dreams?

Correlation(s) in Python

Correlation and significance testing between two or more variables in Python.

Sleep spindles detection

A simple and efficient wavelet-based sleep spindles detector in Python.

EEG bandpower

Compute the average bandpower of an EEG signal in Python.

Repeated measures ANOVA

Two-way mixed-design ANOVA in Python.

CONN Toolbox: extract and plot ROI-to-ROI connectivity matrix

Extract and plot functional connectivity matrices from the CONN toolbox second-level results folder (Python and Matlab)

CONN Toolbox: plot denoised BOLD timeseries of a pair of ROIs

A short guide on how to plot BOLD timeseries of one or two regions of interests (ROIs) from CONN toolbox second-level results folder