  Clinical-grade wearable sleep monitoring is a challenging problem since it
requires concurrently monitoring brain activity, eye movement, muscle activity,
cardio-respiratory features and gross body movements. This requires multiple
sensors to be worn at different locations as well as uncomfortable adhesives
and discrete electronic components to be placed on the head. As a result,
existing wearables either compromise comfort or compromise accuracy in tracking
sleep variables. We propose PhyMask, an all-textile sleep monitoring solution
that is practical and comfortable for continuous use and that acquires all
signals of interest to sleep solely using comfortable textile sensors placed on
the head. We show that PhyMask can be used to accurately measure sleep stages
and advanced sleep markers such as spindles and k-complexes robustly in the
real-world setting. We validate PhyMask against polysomnography and show that
it significantly outperforms two commercially-available sleep tracking
wearables, Fitbit and Oura Ring.
