Persons with 
sleep disordered breathing (SDB) may, or may not, recognize that they have symptoms of SDB, and / or that they may be at-risk of, or suffering certain 
health problems associated with SDB, including death. The disclosed Energy Conversion Monitor (ECM) sensor, when embodied, for example, in a wearable upper-armband format, has been demonstrated to be more sensitive and responsive than 
pulse oximetry monitoring of blood 
oxygen saturation as an indication of 
hypoxic stress induced by SDB, and is compatible with: (1) inclusion in sleep laboratory polysomnograph (PSG) testing 
instrumentation, (2) home-based diagnostic testing for SDB, (3) control of home-use 
airway therapy devices, (4) continuous remote surveillance and refinement of 
airway therapy, and (5) spot-check and continuous surveillance of 
sleep quality in the general 
population. The disclosed ECM also provides new measurements of physiologic stress during and following exercise. When applied during initial care of premature newborn infants, it offers improved therapeutic guidance during their transition from their limited 
in utero oxygen supply conditions, to the increased 
oxygen availability from 
breathing air. When applied during 
resuscitation of persons suffering from hypoxia and during reperfusion of ischemic tissue, such as during treatment of 
ischemic stroke, or 
ischemic heart attack, the ECM sensor can provide objective guidance regarding the safe and effective resupply of oxygen to the hypoxia-adapted tissue to help reduce or prevent microvascular 
occlusion and cellular injury. As a continuously worn physiologic surveillance monitor, the ECM offers the potential of 
early detection of 
sepsis. For the elderly and infirm, the ECM offers a convenient and comfortable means of continuously assessing variations in status while awake and asleep.