Introduction The interplay of daily life factors, including mood, physical activity, or light exposure, influences sleep architecture and quality. Laboratory-based studies often isolate these determinants to establish causality, thereby sacrificing ecological validity. Furthermore, little is known about time-of-year changes in sleep and circadian-related variables at high resolution, including the magnitude of individual change across time of year under real-world conditions. Objectives This study investigates the combined impact of sleep determinants on individuals' daily sleep episodes to elucidate which waking events modify sleep patterns. A second goal is to describe high-resolution individual sleep and circadian-related changes across the year to understand intra- and interindividual variability. Methods and analysis This study is a prospective cohort study with a measurement-burst design. Healthy adults aged 18-35 (N = 12) will be enrolled for 12 months. Participants will continuously wear actimeters and pendant-attached light loggers. A subgroup will also measure interstitial fluid glucose levels (n = 6). Every four weeks, all participants will undergo three consecutive measurement days of four ecological momentary assessments each day ("bursts") to sample sleep determinants during wake. Participants will also continuously wear temperature loggers (iButtons) during the bursts. Body weight will be captured before and after the bursts, and visual function will be tested in the laboratory. The bursts are separated by two at-home electroencephalogram (EEG) recordings each night. Circadian phase and amplitude will be determined during the bursts from hair follicles, and habitual melatonin onset will be derived through saliva sampling. Environmental parameters (bedroom temperature, humidity, and air pressure) will be recorded continuously. Ethics and dissemination The Ethics Committee of the Technical University of Munich approved this study (#2023-653-S-SB). We adhere to research standards including the Declaration of Helsinki and open science principles. Results will be made available as future peer-reviewed publications and contributions to conferences.

A.M.B received financial support from the German Sleep Society (Deutsche Gesellschaft fuer Schlafforschung und Schlafmedizin e.V.) for the submitted work, L.H. has previously been employed at Mentalab GmbH (prior to the submitted work) but is no longer affiliated with the company, M.S. received financial support from the TUM Seed Fund and the Max Planck Society (Max Planck Free-Floating Research Group), V.P. is currently employed at the sleep laboratory of the Klinikum Rechts der Isar, Munich, Germany in which the laboratory-based recording will take place, A.K. is a shareholder of BodyClock Technologies GmbH and receives partial licencing fees from BodyClock; all other authors declare no financial relationships with any organisation that might have an interest in the submitted work in the previous three years; all authors declare no other relationships or activities that could appear to have influenced the submitted work.

This work is supported by the TUM Seed Fund, the Max Planck Society (Max Planck Free-Floating Research Group to M.S.) and the German Sleep Society (Deutsche Gesellschaft fuer Schlafforschung und Schlafmedizin e.V., award to A.M.B.).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethics committee of the Technical University of Munich gave ethical approval for this work (#2023-653-S-SB).

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Data collection has not yet started. We will publish code under the MIT License, and materials and data under the Creative Commons (CC-BY) license on GitHub.