A wireless wearable device to passively detect fatigue in a user may include a suite of sensors including but not limited to accelerometry sensors for generating motion signals in response to a user's body motion, force sensors for generating force signals in response to force exerted by a body portion on the force sensor, and biometric sensors for generating biometric signals indicative of biometric activity including GSR, EMG, bioimpedance, image sensors, and arousal in the SNS. The suit of sensors may operate to passively determine, one or more of TRHR, systemic inflammation (I), contraction (C) (e.g., due to dehydration), stress, fatigue, and mood without any intervention or action on part of the user. The suite of sensors may comprise sensors distributed among a plurality of wireless wearable devices that are wirelessly linked and may share sensor data and data processing in making determinations of fatigue in the user.
