We tend to think that poor sleep is something we can just shake off – a couple of early nights and you’ll have caught up, right? But maybe it’s not so simple. New research tracked one woman’s activity for 19 weeks, revealing the impact that daily life could be having on our minds even days later.
The participant was first author Ana María Triana of Aalto University, Finland. During the five-month study period, wearable technology and smartphone data were used to track her activities and physiological markers, and she underwent a total of 30 functional magnetic resonance imaging (fMRI) scans to assess cognitive functions like attention and memory.
“Our behavior and mental states are constantly shaped by our environment and experiences,” Triana said in a statement. “Yet, we know little about the response of brain functional connectivity to environmental, physiological, and behavioral changes on different timescales, from days to months.”
First author and study participant Ana Triana wore a wrist tracker and smart ring to collect daily data for 19 weeks.
Image credit: Matti Ahlgren / Aalto University 2024
The longitudinal nature of the study is what makes it so unusual. It’s rare to be able to capture so much monitoring data over a continuous period, and Triana’s dual role as both participant and researcher gave her a unique insight into how best to conduct these types of studies.
“Brain scans are useful tools, but a snapshot of someone lying still for half an hour can only show so much. Our brains do not work in isolation,” Triana said. The wearables that were used – an Oura smart ring and a medical-grade wrist monitor – were therefore crucial to the success of the project.
“At the beginning, it was exciting and a bit stressful. Then, routine settles in and you forget,” recalled Triana. During the study, she continued with her normal daily routine, with the addition of the periodic fMRI scans and completing surveys about her mood using a smartphone app.
The picture that emerged from the data indicates that our brains’ responses to daily activities are not isolated and immediate. Two distinct patterns were seen – a short-term response that lasted around a week, and a long-term wave of more gradual effects.
“We find traces of past behavior and physiology in brain connectivity that extend up as far as 15 days,” the authors write in their paper.
One night of disturbed sleep can make focusing on work the next day a tricky task, but it might also continue to negatively impact your memory and cognition a whole week later. Conversely, a workout might give you an instant buzz, but according to these results, you could also still be experiencing the positive effects for up to two weeks.
Restless sleep was found to correlate with decreased connectivity between nodes of the default mode network (which is most active when we’re not engaging in specific tasks) and somatomotor network (responsible for physical sensations and movement).
Image credit: Ana Triana et. al / Aalto University
The research identified a strong link between heart rate variability and brain connectivity – the way in which different regions of the brain interact with each other to perform complex functions – especially during periods of rest. Physical activity was also identified as a strong influence on brain connectivity.
The researchers hope their study can serve as a proof-of-concept for future research, and they’ve made their data freely available to other scientists. Combining brain imaging snapshots with the big-picture data that wearable trackers can provide gives a better idea of someone’s overall brain health and could help identify problems early.
“Linking brain activity with physiological and environmental data could revolutionize personalized healthcare, opening doors for earlier interventions and better outcomes,” Triana said.
The study is published in PLOS Biology.
