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Floor hiemstra


Description of project

I studied Technical Medicine at the Technical University Delft, LUMC and Erasmus MC. For my PhD research, I joined the group of prof. dr. Joke Meijer at the LUMC, in collaboration with the LUMC Intensive Care Unit to study circadian rhythms in intensive care patients. Sleep and circadian rhythms in intensive care unit (ICU) patients are severely disturbed, potentially due to effects of the critical illness, sleep-altering medication and the noisy ICU environment. ICU patients generally receive continuous enteral feeding, are exposed to dim light throughout the day and night and their sleep is frequently interrupted by alarms and clinical interventions, all unfavorable factors for circadian rhythm alignment. Disruption of the circadian system has been associated with poor clinical outcomes such as impaired immune functions, delirium, hormonal and metabolic disturbances and fatigue. In my research, I will study the relationship between the temporal dynamics of vital sign profiles and clinical outcomes in ICU patients and investigate whether the implementation of well-timed cyclic feeding regimens and regular light schedules could improve circadian rhythm alignment measured with multiple methods and clinical outcomes.

My interest for circadian rhythms was born early, at high school my friend and I discovered, and investigated, that we are different chronotypes (with me being an early type). For a school project we investigated the difference between chronotypes and even visited a project at the LUMC. Ever since then, the biological clock was an interesting concept for me. Besides researching, I love to cycle, from small trips around my hometown Rotterdam to bike packing trips through Europe. I also like to run and swim. And when I am tired of doing sports, I like to make music or mess around with my sewing machine. At last, my favorite language is Python.



November 2021

Works at

Leiden University Medical Centre




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The BioClock Consortium is funded by the NWA-ORC programme of the Dutch Research Council (NWO; project number 1292.19.077).