Chronotype Misalignment and Memory: Exploring Circadian Rhythms, Sleep, and Episodic Memory Retention with Machine Learning Insights

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Shijia Yin¹ (syin84@gatech.edu), Elyse Carlson¹, Jillian Connolly¹, Mark Wheeler¹; ¹Georgia Institute of Technology

Human cognition has evolved alongside circadian rhythms; however, the operation of modern society sometimes asks individuals to work against their biological peak times. This study examines how chronotype misalignment with learning schedules affects memory consolidation by combining behavioral testing and machine learning-based chronotype classification. This research investigated episodic memory retention across different encoding and retrieval time points. We hypothesized that chronotype would affect memory performance according to time tested. Participants (n=130) were pseudo-randomly assigned to encode pairs of different pictures of faces and locations with words either approximately 8 AM or 8 PM during Week 1, followed by an immediate retrieval test. Week 2 assessed delayed retrieval, which also assigned participants into morning or evening sessions pseudo-randomly. Throughout the week, sleep data were recorded via actigraphy, allowing us to model individual chronotypes using Gaussian Mixture Modeling (GMM). Results revealed a significant time-of-day effect for the evening-type group: memory accuracies were significantly higher when encoding occurred approximately 8 PM compared to 8 AM, both for immediate and delayed retrieval accuracies. Moreover, memory decay (delta difference) was significantly lower when the evening-type encoded information at their biological peak (8 PM), suggesting enhanced consolidation efficiency. In contrast, the morning-type exhibited no significant performance variation across time conditions. These findings highlight the critical role of circadian alignment in memory retention. Future applications could be based on chronotype-aware scheduling in education and cognitive interventions to optimize learning outcomes. Additionally, this work may help people mitigate memory decline and provide ideas on sleep-chronotype-based memory enhancement strategies.

Topic Area: LONG-TERM MEMORY: Episodic