The Active Brain Project: A Naturalistic Observational Study of Lifestyle Habits, Cognition and Stress in Day and Night Shift Workers

Background Worker wellbeing is increasingly recognised as a major public health and organisational concern, and night shift work has been associated with a adverse mental, physical, cognitive outcomes. At the same time, many workplace wellbeing interventions have shown limited effectiveness, highlighting the need for a better understanding of how everyday lifestyle behaviours influence stress, wellbeing, and cognition in real-world settings. Methods Participants aged 18 to 70 years old were recruited between March and 2025 and between October and December 2025. Eligibility required no diagnosis of diabetes, prediabetes, eating disorders, neurological disorders, traumatic brain injury or cognitive impairment. The study involved 14 days of remote monitoring during which participants completed an intake questionnaire on the first day, then wore a smartwatch continuously and responded to three daily ecological momentary assessments followed by a cognitive test every other day. A subgroup of night shift workers also fitted with a blinded continuous glucose monitor for 10 days and completed detailed food diaries. Measures included demographics, mental wellbeing, stress, anxiety, depression, sleep, diet, physical activity, social interactions, mood, fatigue, pain, and cognitive performance. The final cohort comprised of 310 participants, including 106 current night shift workers, and participants completed on average 73% of scheduled daily assessments while wearing the smartwatch for a mean of 20 hours per day. Discussion The Active Brain Project provides a multimodal and high-frequency dataset collected in free-living conditions across a diverse working population. By integrating wearable, questionnaire, dietary, and cognitive test data, this study creates opportunities to examine how lifestyle and occupational factors relate to stress, mental wellbeing and cognitive function. These findings may help guide future personalised and organisational strategies to support worker health and inform the design of more effective workplace interventions.