Assessing infants' sleep in the home setting: designing rational study approaches

The methods used for assessing infants' sleep vary widely, and the insights provided by each method are not necessarily interchangeable. Direct physiological measurements are often performed in hospital environments with extensive and controllable instrumentation, whereas at-home assessments have been based on parental questionnaires and diaries or actigraphy measurements. There is a rising need for the establishment of objective at-home methods to improve ecological validity in assessing infant sleep. Here, we review how specific research questions can be aligned with at-home assessment methods, ranging from indirect parental interviews to direct modern measures with unobtrusive sensors (wearables, in-bed sensors, video), and their integrated machine learning -based analytics. We discuss the nature of information available from each method in relation to the physiological or behavioural sleep phenomena. The currently available methods may support disruptive science, including globally harmonized and scaled-up studies across cultures and geographic locations, including fully decentralized developmental research and sleep-focused health care. IMPACT: The paper raises the practical and scientific need to study infant sleep using methods that are both objective and ecologically valid, thereby supporting the use of direct at-home measurements. The paper emphasizes the multifaceted nature of infant sleep, which precludes its assessment as a solitary entity and calls for clear research questions to identify measurable phenomena in sleep-related physiology or behavior Presently available research methods for at-home studies are described and compared in relation to their information content, practical utility and caveats Various analytic results and sleep metrics are described in relation to the underlying sleep physiology or behavior. The overall message emphasizes the need to establish a solid end-to-end waterfall framework in infant sleep research, spanning study questions, sleep phenomena, recording methods, and data analytics.