In a rare, longitudinal study, researchers from Aalto University and the University of Oulu tracked one person’s brain and behavioural activity for five months using brain scans and data from wearable devices and smartphones.
‘We wanted to go beyond isolated events,’ says research leader Ana Triana. ‘Our environment and experiences constantly shape our behaviour and mental states. Yet, we know little about the response of brain functional connectivity to environmental, physiological, and behavioural changes on different timescales, from days to months.’
The study discovered that our brains don’t react to daily life in short, isolated bursts. Instead, brain activity changes in response to sleep patterns, physical activity, mood, and respiration rate over several days. This implies that even a workout or a restless night from last week could still impact your brain — and consequently your attention, thinking, and memory — well into next week.
The research also revealed a strong link between heart rate variability, which measures the heart’s adaptability, and brain connectivity, particularly during rest. This suggests that activities that affect our body’s relaxation response, such as stress management techniques, could influence the wiring of our brains even when we are not actively focusing on a task. The study also found that physical activity has a positive impact on the interaction between different brain regions, potentially affecting memory and cognitive flexibility. Furthermore, even small changes in mood and heart rate had lasting effects for up to fifteen days.
The study goes beyond a snapshot.
The research is unusual because few brain studies involve detailed monitoring over days and weeks. ‘The use of wearable technology was crucial’, says Triana. ‘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 was the subject of the research, being monitored as she went about her daily life. Her dual role as both lead author and study participant added complexity but also provided firsthand insights into how to best maintain research integrity during several months of personalized data collection.
‘At the beginning, it was exciting and a bit stressful. Then, routine settles in, and you forget,’ says Triana. Qualitative data from mood surveys complemented data from the devices and twice-weekly brain scans.
The researchers identified two distinct response patterns: a short-term wave lasting under seven days and a long-term wave of up to fifteen days. The short-term wave reflects rapid adaptations, such as how the focus is impacted by poor sleep, but it recovers quickly. The long wave suggests more gradual, lasting effects, particularly in areas tied to attention and memory.
Single-subject studies offer opportunities for improving mental health care.
The researchers hope their innovative approach will inspire future studies that combine brain data with everyday life to help personalise mental health treatment.
‘We must bring data from daily life into the lab to see the full picture of how our habits shape the brain, but surveys can be tiring and inaccurate,’ says study co-author, neuroscientist and physician Dr Nick Hayward. ‘Combining concurrent physiology with repeated brain scans in one person is crucial. Our approach gives context to neuroscience and delivers very fine detail to our understanding of the brain.’
The study is also a proof-of-concept for patient research. Tracking brain changes in real-time could help detect neurological disorders early, especially mental health conditions where subtle signs might be missed.
“Linking brain activity with physiological and environmental data could revolutionize personalized healthcare, opening doors for earlier interventions and better outcomes,” says Triana.