Making Sense of Sleep: Multimodal Sleep Stage Classification in a Large, Diverse Population Using Movement and Cardiac Sensing. - Bing Zhai; Ignacio Perez-Pozuelo; Emma A. D. Clifton; João R. M. Palotti; Yu Guan (Proc. ACM Interact. Mob. Wearable Ubiquitous Technol., 2020)