My dentist tells me I grind my teeth, it probably isn’t every night, but we have no way of telling- challenge accepted.
• Grinding teeth, pressure resistor in thin mouth guard
• Breathing, holding a mirror in front of the mouth/nose senses breath, so humidity if a sensor sees changes fast enough
• Pulse & Oximetry, a finger probe but I wonder what kind of belt, or if something close to the temples or neck could get a good reading
Movement, accelerometer, a gyroscope would give what side you sleep on as well if calibrated
One of my sisters wore a mask for monitoring breathing while she slept, it was a large piece of lab equipment a ‘darth vader mask’, there is room for improvement. Seems that most current sensors are external/environmental, that makes them not intrusive at all:
pillow (person can move off)
pyjamas (not always the same)